Serotonin receptor subtype with anxiolytic effects, particularly in amygdala and hippocampus, and the primary target mediating SSRI therapeutic benefit. As an autoreceptor on serotonin neurons, it temporarily reduces serotonin release until desensitization occurs; buspirone acts directly on this receptor.

Serotonin receptor subtype whose activation produces anxiety-increasing effects in amygdala and BNST. Early SSRI-induced activation of 5-HT2C receptors (before 5-HT1A desensitization) causes initial treatment worsening; over weeks, these receptors desensitize, allowing anti-anxiety effects to emerge.

Serotonin-transporter-linked polymorphic region. A genetic variant in the SERT gene promoter once thought to predict depression and anxiety risk. The short allele was widely studied but large replication efforts (including Culverhouse et al., 2018) found no reliable main effect. Now considered a cautionary tale in psychiatric genetics.

A plan under Section 504 of the Rehabilitation Act providing accommodations (but not specialized instruction) for students with disabilities.

95% Credible Interval — a Bayesian statistic indicating the range within which the true value falls with 95% probability given the observed data. Unlike a confidence interval, it makes a direct probability statement about the parameter.

A subtype of alpha-2 adrenergic receptor concentrated in the prefrontal cortex. Guanfacine is a selective α2A agonist, which is why it improves attention and impulse control with less sedation than clonidine (which activates all alpha-2 subtypes).

American Academy of Child and Adolescent Psychiatry — the leading U.S. professional organization for child and adolescent psychiatrists. Publishes practice parameters and clinical guidelines for pediatric mental health conditions including ADHD.

American Academy of Pediatrics — the primary U.S. professional organization for pediatricians. Publishes clinical practice guidelines for ADHD diagnosis and treatment in children and adolescents, most recently updated in 2019.

Adolescent Brain Cognitive Development Study. An ongoing longitudinal cohort of roughly 12,000 U.S. youth, providing the most granular developmental neuroimaging data available for studying how the brain develops through adolescence.

Ambulatory blood pressure monitoring — a method of measuring blood pressure at regular intervals over 24 hours using a portable device, considered the gold standard for diagnosing hypertension in pediatric patients.

Brief staring spells caused by abnormal brain electrical activity. Can mimic inattention.

A change in how instruction or testing is delivered that removes barriers without altering content or expectations. Contrast with modification, which changes what the student is expected to learn.

Adverse Childhood Experience. An index of childhood trauma exposure linked to increased risk of psychiatric and medical conditions.

Acceptance and Commitment Therapy; transdiagnostic psychotherapy emphasizing values clarification, acceptance of unwanted internal experiences (thoughts, sensations, emotions), and committed action toward meaningful life goals. Shows efficacy across anxiety disorders as an alternative to trauma-focused or disorder-specific CBT.

A wrist-worn device that records movement over days to weeks, used to objectively measure sleep-wake patterns, circadian rhythms, and activity levels. Widely used in sleep medicine, research, and clinical monitoring across many conditions.

Americans with Disabilities Act. Federal civil rights law prohibiting discrimination against individuals with disabilities.

Brand name for mixed amphetamine salts (immediate-release). A first-line stimulant for ADHD combining four amphetamine salts.

Extended-release formulation of mixed amphetamine salts using a beaded delivery system. Duration approximately 10-12 hours.

A subscale of the Conners Rating Scales that specifically measures core ADHD symptoms. Often used as a brief screening measure rather than a full diagnostic assessment.

ADHD Rating Scale. A standardized symptom severity measure based on DSM criteria, used in clinical trials and practice.

ADHD Rating Scale-IV or -5 — a parent/teacher rating scale directly mapping DSM-IV or DSM-5 ADHD symptoms. Each of the 18 symptoms is rated 0-3 for frequency. Widely used in clinical trials and clinical practice for diagnosis and monitoring.

The degree to which a patient follows prescribed treatment recommendations.

Autism Diagnostic Interview-Revised. A structured caregiver interview for autism diagnosis.

Autism Diagnostic Observation Schedule, 2nd Edition. A standardized assessment tool for diagnosing autism spectrum disorder.

Alpha-2A Adrenergic Receptor Gene — the gene encoding the receptor target of guanfacine. Genetic variants in ADRA2A have been studied for association with ADHD symptoms and treatment response to alpha-2 agonist medications.

A brief self- and parent-report measure of irritability in children and adolescents. Specifically designed to measure the trait-level (tonic) irritability associated with mood and disruptive behavior disorders.

A substance that binds to a receptor and activates it, mimicking the natural signaling molecule.

Antidepressant-Induced Emotional Blunting — a side effect in which antidepressant medication reduces the intensity of all emotions, not just negative ones, sometimes described as feeling 'flat' or 'numb.'

An intensely distressing sense of inner restlessness and inability to sit still. A potential side effect of some psychiatric medications.

A medication that activates alpha-2 adrenergic receptors, reducing sympathetic nervous system activity.

A class of medications (guanfacine, clonidine) that stimulate alpha-2 adrenergic receptors, reducing norepinephrine release. Used in psychiatry for ADHD, tic disorders, anxiety-related hyperarousal, and insomnia, and in general medicine for hypertension and opioid withdrawal.

Tertiary amine tricyclic antidepressant with broad receptor activity (serotonin, norepinephrine, histamine, acetylcholine). Used primarily for chronic pain and migraine prophylaxis rather than anxiety due to its side effect burden and overdose lethality compared to SSRIs.

A stimulant medication that enhances dopamine and norepinephrine signaling through reuptake inhibition plus forced release. Includes mixed amphetamine salts (Adderall) and lisdexamfetamine (Vyvanse).

A brain structure involved in processing fear, emotional memory, and threat detection. Also plays a role in reward processing and social cognition.

Excessive activation of the amygdala (the brain's threat-detection center) in response to emotional stimuli. A core finding in anxiety disorders, PTSD, and mood disorders, and a contributor to emotional dysregulation more broadly.

The inability to experience pleasure from activities that are normally enjoyable.

A substance that binds to a receptor and blocks its activation.

Changing environmental triggers before a behavior occurs to prevent problem behaviors.

A brain region involved in error detection, conflict monitoring, and emotional regulation.

A brain network relationship where one network's activation reliably coincides with another network's deactivation. The default mode network and task-positive network are anti-correlated: when one turns on, the other turns off. In ADHD, this switching is unreliable.

A state of excessive worry, apprehension, or fear that is disproportionate to the situation. When persistent and impairing, it constitutes an anxiety disorder. Anxiety is among the most common psychiatric comorbidities in ADHD.

Extended-release methylphenidate using a multi-particulate beaded system with a 40:60 immediate-to-delayed release ratio.

An atypical antipsychotic with dopamine partial agonist activity, used as adjunctive treatment for depression and irritability across diagnostic categories.

Two competing models of ADHD: the arousal model proposes that ADHD symptoms arise from under-stimulation of the brain (leading to sensation-seeking and inattention), while the inhibition model proposes that the core deficit is an inability to suppress inappropriate responses.

Autism Spectrum Disorder — a neurodevelopmental condition characterized by persistent differences in social communication and interaction, along with restricted, repetitive patterns of behavior or interests. Frequently co-occurs with ADHD, with prevalence estimates of 20-50% comorbidity depending on the sample.

The co-occurrence of Autism Spectrum Disorder with another condition such as ADHD. The DSM-5 removed the previous prohibition on dual ASD-ADHD diagnosis, recognizing that 30-50% of individuals with ASD independently meet criteria for ADHD with distinct impairment from each disorder.

Adult ADHD Self-Report Scale. A brief screening tool for ADHD symptoms in adults.

Any device or software that helps a person with a disability perform tasks they would otherwise find difficult.

A selective norepinephrine reuptake inhibitor (NRI) used for attention-deficit disorders. Brand name: Strattera. Takes 6–8 weeks for full therapeutic effect, unlike the immediate action of stimulants.

Area Under the Curve — a statistical measure of diagnostic accuracy (in ROC analysis) or total drug exposure over time (in pharmacokinetics). Higher AUC values indicate better diagnostic discrimination or greater medication exposure.

Adding a second medication or intervention to an existing treatment to enhance the overall response.

A neurodevelopmental condition characterized by differences in social communication and restricted or repetitive behaviors. Frequently co-occurs with ADHD; DSM-5 permits dual diagnosis. Abbreviated ASD.

Combination of serdexmethylphenidate (a prodrug) and dexmethylphenidate. Designed to provide both immediate and extended coverage.

A group of subcortical nuclei (including the caudate, putamen, and globus pallidus) involved in motor control, habit formation, and reward processing. Structural and functional differences in basal ganglia circuits are consistently observed in ADHD neuroimaging research.

Neural pathways connecting the basal ganglia (deep brain structures) with the cortex. These circuits regulate movement, motivation, habit formation, and reward processing, and are implicated in a wide range of neuropsychiatric conditions.

The prevalence of a condition in the population being tested, which directly affects the meaning of test results.

The statistical principle that a screening test's predictive accuracy depends not only on its sensitivity and specificity but also on how common the condition is in the population being tested. Low base rates dramatically reduce positive predictive value.

A statistical approach that calculates the probability of one treatment being better than another by combining prior evidence with new data. Unlike traditional statistics, it produces direct probability statements rather than p-values.

Brain-Derived Neurotrophic Factor. A protein essential for the growth and survival of neurons, involved in neuroplasticity and learning.

A therapeutic technique that systematically increases engagement in meaningful activities to counteract patterns of avoidance and withdrawal.

The brain's ability to suppress an automatic response and pause before acting, allowing deliberate decision-making. A foundational concept in Barkley's model of ADHD, where deficient behavioral inhibition is considered the core deficit.

An evidence-based psychosocial intervention that teaches parents specific behavior management techniques including positive reinforcement, structured routines, and consistent consequences. Recommended as first-line treatment for preschoolers with ADHD.

A class of medications that enhance GABA activity to produce sedative, anxiolytic, and muscle-relaxant effects. Generally avoided in ADHD populations due to cognitive dulling, dependence risk, and potential for misuse.

The proportion of an administered drug that reaches the bloodstream in active form.

FDA classifications for generic drug substitutability. AB-rated generics are considered therapeutically equivalent and can be freely substituted. BX-rated products have insufficient evidence of equivalence and require clinical judgment when switching.

A subgroup of patients within a diagnosis who share distinct biological characteristics (brain imaging patterns, genetic profiles, or biomarkers) that may predict different treatment responses or clinical courses.

Behavior Intervention Plan. A plan based on an FBA that outlines strategies for addressing problem behaviors in school settings.

The FDA's strongest safety warning on a medication label (formally called a Boxed Warning), indicating serious or life-threatening risks.

A research method in which trained observers who do not know which treatment group a participant belongs to rate their behavior in real-time. Considered more objective than parent or teacher rating scales.

Body Mass Index. A measure of body weight relative to height, widely used in clinical assessment and growth monitoring.

Behavioral Parent Training — an evidence-based intervention in which parents learn structured techniques (e.g., contingency management, positive reinforcement, consistent consequences) to manage child behavior. Recommended as first-line treatment for preschool ADHD and as an adjunct to medication for school-age children.

Behavior Rating Inventory of Executive Function, 2nd Edition. A rating scale measuring executive function abilities in daily life.

A rating scale that screens across many types of problems rather than focusing on one disorder.

An antidepressant (Wellbutrin) sometimes used off-label for attention and mood disorders. A norepinephrine-dopamine reuptake inhibitor (NDRI).

Columbia Suicide Severity Rating Scale — a structured interview tool used to assess suicidal ideation and behavior. Widely used in clinical trials and clinical practice for suicide risk screening.

Collaborative ADHD Developmental Disabilities Intervention — a structured treatment program for children with both ADHD and developmental disabilities.

Canadian ADHD Resource Alliance. Publishes Canadian guidelines and medication charts for ADHD treatment.

Adenosine receptor antagonist and the most widely consumed psychoactive substance. In anxiety contexts, caffeine can provoke or exacerbate panic attacks and generalized anxiety symptoms through sympathetic activation; doses above 200-300 mg/day are clinically relevant.

An anticonvulsant (Tegretol) used for bipolar disorder and seizures. Strong CYP3A4 inducer affecting metabolism of many other medications.

A class of neurotransmitters that includes dopamine and norepinephrine (and epinephrine). Synthesized from the amino acid tyrosine. These chemicals are essential for prefrontal cortex function and are the primary targets of ADHD medications. PFC performance follows an inverted-U curve for catecholamine levels.

Reduced activity in brain circuits that use catecholamine neurotransmitters (dopamine and norepinephrine). Implicated in ADHD, depression, Parkinson's disease, and other conditions where dopamine or norepinephrine signaling is disrupted.

The chemical family of neurotransmitters that includes dopamine and norepinephrine. Central to understanding conditions involving attention, motivation, and executive function.

A former FDA pregnancy risk category indicating that animal studies showed adverse fetal effects but no adequate human studies exist. This system was replaced in 2015 by narrative risk summaries, but the letter categories are still widely referenced.

Child and Adolescent Trauma Screen — a brief screening tool for trauma exposure and PTSD symptoms in youth aged 3–17.

A deep brain structure involved in regulating motor activity and cognitive control.

A framework for prioritizing which condition to treat first when multiple diagnoses coexist. A 'primary' condition directly causes or worsens a 'secondary' condition — treating the primary condition may resolve the secondary one.

Child Behavior Checklist — a broadband parent-report instrument that screens for a wide range of emotional and behavioral problems in children ages 1.5–18. Used in ADHD evaluations to screen for comorbid conditions beyond the narrow ADHD symptom domain.

Comprehensive Behavioral Intervention for Tics — a structured behavioral therapy for tic disorders that includes habit reversal training, relaxation techniques, and functional interventions. Recommended as first-line treatment for Tourette syndrome.

Cognitive Behavioral Therapy — a structured, evidence-based psychotherapy that targets maladaptive thought patterns and behaviors. In ADHD, CBT is a first-line psychosocial treatment for adults (with strong RCT support) and is used in adolescents primarily for comorbid anxiety or depression.

Cognitive Disengagement Syndrome — see 'Cognitive Disengagement Syndrome.'

The point at which increasing the dose or intensity of a measure no longer produces additional effect.

A brain region traditionally associated with motor coordination, now known to contribute to cognitive timing and error correction.

Center for Epidemiologic Studies Depression Scale. A screening tool for depressive symptoms.

Carboxylesterase 1. The liver enzyme primarily responsible for metabolizing methylphenidate. Genetic variants affect drug levels.

Cultural Formulation Interview — a set of questions in the DSM-5 designed to help clinicians understand how a patient's cultural background influences their experience of illness, help-seeking, and treatment expectations.

Children's Global Assessment Scale. A clinician-rated measure of overall functioning in children.

Clinical Global Impression — Improvement scale. A single-item clinician rating of how much a patient has improved since treatment began, scored 1 (very much improved) to 7 (very much worse). CGI-I ≤ 2 (much or very much improved) typically defines treatment response in clinical trials.

Clinical Global Impressions-Severity scale. A clinician-rated measure of overall symptom burden, scored from 1 (not ill) to 7 (extremely ill).

The legal obligation under IDEA for schools to identify, locate, and evaluate all children with suspected disabilities.

A requirement under the Individuals with Disabilities Education Act (IDEA) that schools must actively identify, locate, and evaluate all children with disabilities who may need special education services, regardless of whether parents have requested evaluation.

A clinical scoring system that classifies the severity of liver disease (A = mild, B = moderate, C = severe). Used to guide medication dosing in patients with hepatic impairment, as many ADHD medications are liver-metabolized.

A healthcare framework for managing long-term conditions through ongoing monitoring and collaborative care.

The ability of a substance (typically melatonin) to shift the timing of the body's circadian clock. Distinct from a sedative effect — a chronobiotic resets when you feel sleepy rather than just making you drowsy.

Treatment approaches that target the body's circadian rhythm system, such as strategically timed light exposure, melatonin administration, or sleep schedule adjustments. Used in sleep disorders, depression, bipolar disorder, and other conditions involving circadian disruption.

Confidence Interval. A statistical range expressing the precision of an estimate, typically at 95% confidence.

Relating to biological rhythms that follow an approximately 24-hour cycle, most notably the sleep-wake cycle. Circadian disruption is common in ADHD and can worsen inattention and emotional dysregulation.

A biological shift toward later sleep-wake timing.

An SSRI antidepressant (Celexa) used for depression and anxiety. Has a dose-dependent risk of QTc prolongation, which strictly limits maximum doses, especially in older adults.

Challenging Horizons Program — Classroom Level Approach to Students. A school-based behavioral intervention that targets academic and organizational skills in students with attention and behavior difficulties.

A pharmacokinetic measure of how efficiently the body removes a drug from the bloodstream.

Whether a statistical finding is large enough to matter in real-world patient care.

An improvement large enough to make a noticeable difference in a patient's daily functioning.

A non-selective alpha-2 adrenergic agonist used for attention disorders, particularly for hyperarousal, sleep difficulties, and as an adjunct to stimulants. Extended-release brand name: Kapvay.

Central nervous system; the brain and spinal cord. CNS-active medications cross the blood-brain barrier and affect neural function.

A systematic review conducted by the Cochrane Collaboration, an international organization that produces gold-standard evidence syntheses. Cochrane reviews follow rigorous, pre-registered methodology and are widely considered the highest level of evidence.

A systematic review published by the Cochrane Collaboration, considered among the highest quality evidence summaries.

A pattern where a child's disruptive behavior leads to harsh parenting, which escalates the child's behavior, which prompts harsher responses — creating a self-reinforcing negative cycle. Originally described by Patterson in research on conduct problems, and a key target of parent training interventions across disruptive behavior disorders.

A necessary helper molecule that an enzyme requires to function. Iron is a cofactor for tyrosine hydroxylase, the enzyme that produces dopamine. Iron deficiency can impair dopamine synthesis and worsen ADHD symptoms.

A structured psychotherapy that targets maladaptive thought patterns and behaviors through skills training, cognitive restructuring, and behavioral activation. Used in ADHD primarily for comorbid anxiety, depression, and as an adjunct for organizational skills.

A neurodevelopmental presentation characterized by mental fogginess, slow processing speed, daydreaminess, and reduced arousal. Statistically separable from ADHD-Inattentive but frequently co-occurring. Formerly called Sluggish Cognitive Tempo (SCT). Not yet a formal DSM diagnosis.

A CBT technique that identifies and challenges distorted thinking patterns.

A measure of effect size expressing the difference between two group means in standard deviation units.

A brief 13-item measure of functional impairment in children and adolescents, covering interpersonal relationships, school performance, and use of leisure time. Used to assess whether ADHD symptoms cause clinically meaningful impairment.

Occurring alongside another condition in the same individual. ADHD has high comorbidity rates: roughly two-thirds of children with ADHD meet criteria for at least one additional psychiatric diagnosis.

The co-occurrence of two or more diagnoses in the same patient. In psychiatry, comorbidity is common and significantly affects treatment planning.

Extended-release methylphenidate using the OROS (osmotic-release oral system) push-pull technology. Duration 10-12 hours with an ascending release profile.

An instructional method that teaches mathematical concepts in three stages: first with physical objects (concrete), then with visual models (representational), then with symbols (abstract). An evidence-based approach in special education and general math instruction.

A behavioral disorder characterized by persistent violation of societal norms and the rights of others.

A range of values within which the true population parameter is likely to fall, typically at 95% confidence.

A family of standardized ADHD rating scales (Conners 3, Conners 4) that use parent, teacher, and self-report forms to quantify symptom severity across inattention, hyperactivity-impulsivity, and associated domains.

Conners Early Childhood — a rating scale designed to assess behavioral, emotional, and developmental concerns in children aged 2–6. Includes ADHD-specific subscales appropriate for the preschool age group.

In behavioral psychology, the consequences (rewards or penalties) that follow a behavior and influence whether it occurs again. Contingency management — systematically structuring these consequences — is a core component of behavioral interventions across many conditions.

A behavioral approach using structured rewards and consequences to shape behavior.

A computerized test that measures sustained attention and impulsivity by requiring the test-taker to respond to target stimuli while inhibiting responses to non-targets over an extended period (typically 15–20 minutes).

A vision disorder that makes near-work painful and is often mistaken for inattention.

Structural changes in DNA where sections of the genome are duplicated or deleted. Rare CNVs have been implicated in a range of neurodevelopmental and psychiatric conditions, particularly when they affect neurodevelopmental gene pathways.

Neural pathways connecting the cerebral cortex with the striatum (part of the basal ganglia). These circuits are critical for executive function, reward processing, and motor control.

Children's Organizational Skills Scale — Parent version. A rating scale that measures a child's organizational, time management, and planning skills as observed by parents.

Cognitive Proficiency Index — a composite score from the WISC-V that measures processing speed and working memory, areas often impaired in ADHD. Comparing CPI to the General Ability Index can reveal ADHD-related cognitive inefficiencies.

Child PTSD Symptom Scale for DSM-5 — a self-report measure for children aged 8–18 that assesses PTSD symptom severity aligned with DSM-5 criteria.

Continuous Performance Test. A computerized test measuring sustained attention and impulse control.

Current Procedural Terminology codes used for billing ADHD-related services. Key codes include 99446-99452 for interprofessional consultation (e.g., psychiatrist advising a PCP) and 90846 for family therapy without the patient present.

A screening tool for substance use risk in adolescents, useful in comprehensive psychiatric assessment.

Corticotropin-releasing hormone; neuropeptide released by hypothalamus that initiates the HPA axis stress cascade by stimulating pituitary ACTH release, which triggers adrenal cortisol secretion. In anxiety disorders, chronic CRH elevation drives persistent HPA axis activation; CRF1 receptor antagonists were developed to block this but failed clinically.

The degree to which different raters (e.g., parent vs. teacher) agree on a child's symptoms. In ADHD assessment, cross-informant agreement is typically moderate because behavior varies across settings — disagreement is expected and clinically informative.

The normal discrepancy between different raters (e.g., parent vs. teacher) when reporting on the same patient.

A clinical trial design in which each participant receives both the experimental and control treatments in sequence, serving as their own control. Reduces between-subject variability but requires a washout period between conditions.

Cytochrome P450 1A2. A liver enzyme metabolizing caffeine and some antipsychotics (notably olanzapine and clozapine). Activity is significantly increased by tobacco smoking, which can lower medication levels.

Blocking or slowing the CYP1A2 liver enzyme, which metabolizes certain medications. When this enzyme is inhibited (by other drugs such as fluvoxamine or ciprofloxacin, or by genetic variation), affected medications may reach higher blood levels. CYP1A2 activity is induced by smoking and cruciferous vegetables.

Cytochrome P450 2D6. A liver enzyme involved in metabolizing many psychotropic medications. Genetic variants and drug interactions affect medication levels.

A situation in which multiple co-prescribed medications all rely on the CYP2D6 liver enzyme for metabolism, creating competition that can lead to unexpectedly high drug levels and increased side effects.

Cytochrome P450 3A4. The most abundant liver enzyme, responsible for metabolizing many psychiatric medications.

A family of liver enzymes (designated CYP followed by numbers and letters, such as CYP2D6 or CYP3A4) responsible for metabolizing most psychiatric medications. Genetic variation in cytochrome enzymes is a major source of individual differences in drug response.

One of two mirror-image forms of a molecule (like left and right hands). In stimulant pharmacology, the d-enantiomer (dextro-) of amphetamine is more potent at releasing dopamine and norepinephrine than the l-enantiomer.

Dopamine Transporter. The protein on presynaptic neurons that recycles dopamine from the synapse. Primary target of stimulant medications.

Two different pharmacological mechanisms for increasing dopamine in the synapse. Methylphenidate primarily blocks the dopamine transporter (DAT) from reabsorbing dopamine, while amphetamines actively push dopamine out of storage vesicles into the synapse.

Dopamine Transporter Gene (SLC6A3) — a gene encoding the dopamine transporter protein. Variations in DAT1 have been associated with ADHD risk and with individual differences in stimulant medication response.

A clinical memory aid (Dosage, Adherence, Tolerability, Efficacy, Response timeline) used to systematically evaluate why an ADHD medication trial may not be working before switching medications.

Methylphenidate transdermal patch. Bypasses first-pass metabolism, allowing lower effective doses. Applied to the hip for 9 hours.

Daily Behavior Report Card. A school-based monitoring tool linking classroom behavior to home consequences.

Dialectical Behavior Therapy. A therapy combining cognitive-behavioral techniques with mindfulness, particularly useful for emotional dysregulation.

Dialectical Behavior Therapy for Children — an adaptation of DBT for preadolescent children that teaches emotion regulation, distress tolerance, and interpersonal skills. Used when emotional dysregulation is a primary treatment target.

Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood — a diagnostic system specifically designed for children from birth to age 5, used when DSM-5 criteria are developmentally inappropriate.

Developmental Coordination Disorder. A motor skills condition causing clumsiness and difficulty with fine and gross motor tasks.

Drug Enforcement Administration — the U.S. federal agency that regulates controlled substances. The DEA sets annual manufacturing quotas for stimulant medications and enforces prescribing rules for Schedule II drugs.

The total amount of a controlled substance that the DEA authorizes U.S. manufacturers to produce in a given year. When quotas are insufficient to meet demand, stimulant medication shortages can result — a recurring problem affecting ADHD patients.

A brain network active during mind-wandering and self-referential thought. Shows abnormal connectivity in several psychiatric conditions.

The normal pattern where the Default Mode Network (active during rest and mind-wandering) deactivates when the Task-Positive Network engages for focused work. In ADHD, this anti-correlation is weaker, allowing mind-wandering to intrude during tasks.

A circadian rhythm disorder in which the natural sleep-wake cycle is shifted significantly later than conventional times, making it very difficult to fall asleep at a socially acceptable hour. Most common in adolescents and young adults.

A structured research method in which a panel of experts completes multiple rounds of anonymous surveys, with feedback between rounds, to converge on areas of agreement. Used when randomized trial evidence is lacking.

A mood disorder characterized by persistent low mood, loss of interest or pleasure, and associated cognitive and physical symptoms. Major depressive disorder is a common comorbidity in ADHD, particularly in adolescents and adults.

A tricyclic antidepressant sometimes used off-label for attention and mood disorders, and neuropathic pain. Works via norepinephrine reuptake inhibition.

Deficient Emotional Self-Regulation. A framework describing emotional dysregulation as a core feature of certain conditions.

The expected pattern of skill acquisition and behavioral change across childhood and adolescence.

Brand name for dextroamphetamine, the d-isomer of amphetamine. Available in immediate-release and spansule (extended-release) forms.

The active (d-) enantiomer of methylphenidate. Achieves the same clinical effect at half the milligram dose. Brand names: Focalin, Focalin XR.

The d-enantiomer of amphetamine, highly potent at dopaminergic synapses. Brand name: Dexedrine.

Incorrectly attributing symptoms to the wrong diagnosis. In ADHD, this commonly occurs when ADHD symptoms are attributed to anxiety or depression (or vice versa), leading to inappropriate treatment.

When a prominent diagnosis causes clinicians to attribute new symptoms to the existing condition rather than considering additional diagnoses.

The degree to which a diagnosis remains consistent over time across repeated assessments.

The systematic process of distinguishing between conditions that share similar symptoms.

A theory proposing that certain genetic variants do not simply increase risk for problems but rather make individuals more sensitive to their environment — for better or worse. In supportive environments, these individuals may thrive more than average.

The time at which endogenous melatonin levels begin rising under dim lighting conditions. A reliable biomarker of circadian phase used clinically to guide the timing of melatonin supplementation. Abbreviated DLMO.

First-generation antihistamine (Benadryl) with anticholinergic properties sometimes used as a sleep aid. Not recommended for anxiety due to cognitive impairment, tolerance, anticholinergic burden, and association with increased dementia risk with long-term use in older adults.

Physical and psychological symptoms arising from abrupt cessation or rapid tapering of psychotropic medications (particularly SNRIs), including dizziness, electric shock-like sensations, nausea, insomnia, and dysphoria. More severe with drugs having shorter half-lives and higher potency; managed by slow tapering schedules.

A structured period off medication to assess whether ongoing treatment is still necessary.

A treatment that changes the underlying trajectory of a condition rather than just managing symptoms — altering the disease course itself rather than reducing current symptom severity. A concept used across neurology (e.g., multiple sclerosis, Alzheimer's) and increasingly discussed in psychiatry.

A childhood condition characterized by severe, recurrent temper outbursts and persistent irritable or angry mood between outbursts. Introduced in DSM-5 to address concerns about overdiagnosis of pediatric bipolar disorder. Abbreviated DMDD.

A disconnection from one's thoughts, feelings, surroundings, or identity, often associated with trauma.

A behavioral technique where a brief, structured pause is introduced before responding to off-task behavior, allowing the child an opportunity to self-correct. Used in classroom behavioral interventions for ADHD.

Diversion is giving or selling a prescribed medication to someone for whom it was not prescribed. Misuse is taking one's own prescribed medication in a way other than directed (e.g., higher doses, non-oral routes). Both are concerns with stimulant medications.

Dim light melatonin onset. The time at which endogenous melatonin levels begin rising under dim lighting conditions. Used as a reliable biomarker for circadian phase and to guide the timing of exogenous melatonin administration.

Disruptive mood dysregulation disorder. A childhood condition characterized by severe, recurrent temper outbursts and persistent irritable or angry mood between outbursts. Introduced in DSM-5 to address concerns about overdiagnosis of pediatric bipolar disorder.

Default Mode Network — a set of brain regions (medial prefrontal cortex, posterior cingulate, precuneus) active during rest and mind-wandering. In ADHD, the DMN shows atypical connectivity and inadequate suppression during tasks requiring focused attention, contributing to lapses in concentration.

An epigenetic mechanism where methyl groups attach to DNA, typically silencing gene expression without changing the DNA sequence. Environmental exposures (stress, toxins, nutrition) can alter methylation patterns, providing a molecular pathway by which experience shapes gene expression across the lifespan.

A neurotransmitter central to reward, motivation, and executive function. Key pathways: mesocortical (ventral tegmental area → prefrontal cortex, involved in attention and working memory), mesolimbic (VTA → nucleus accumbens, involved in reward and motivation), and nigrostriatal (substantia nigra → striatum, involved in motor control). The primary target of stimulant medications in ADHD.

An increase in the number or activity of dopamine transporter proteins, which remove dopamine from the synapse. This may occur as the brain adapts to chronic stimulant treatment, potentially contributing to tolerance.

The region of the prefrontal cortex most associated with working memory and cognitive control.

The relationship between a medication dose and the magnitude of its therapeutic or adverse effects.

A study design where neither participants nor researchers know which intervention each participant is receiving.

Daily Report Card — a behavioral intervention tool where teachers rate a child's behavior on specific targets each day, and parents deliver rewards at home based on the ratings. A cornerstone of school-based ADHD behavioral treatment.

Dopamine Receptor D4 Gene — a gene encoding one type of dopamine receptor. The 7-repeat allele of DRD4 has been associated with ADHD in genetic studies and may influence response to behavioral interventions.

A planned period off medication, used to reassess ongoing need, evaluate side effects, or allow physiological recovery.

When one medication affects the metabolism, absorption, or action of another medication.

Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (2022). The standard classification system for psychiatric diagnoses in the United States.

Diffusion Tensor Imaging. A neuroimaging technique that maps white matter pathways in the brain.

A formal legal proceeding to resolve disputes between families and schools about special education services.

An SNRI antidepressant (Cymbalta) used for depression, anxiety, and chronic pain conditions. Also approved for stress urinary incontinence.

Dual-energy X-ray Absorptiometry. A scan measuring bone density, sometimes relevant for monitoring growth during medication treatment.

Dual-energy X-ray Absorptiometry — a low-radiation scan that precisely measures body composition (bone density, fat mass, lean mass). Used in ADHD research and monitoring to assess whether stimulant medications affect growth and body composition.

A clinical term for Specific Learning Disorder with impairment in mathematics, affecting number sense, calculation, and mathematical reasoning.

A clinical term for difficulties with written expression, particularly affecting handwriting, spelling, and the mechanics of getting thoughts onto paper.

A state of pronounced unease, irritability, or emotional discomfort.

An inability to maintain a regular rhythm during repetitive movements (e.g., finger tapping). A 'soft neurological sign' that may indicate immature motor system development in young children. Also refers to abnormal heart rhythms in cardiology.

A group of conditions characterized by persistent disturbances in eating behavior and related distress.

Electrocardiogram. A test recording the heart's electrical activity, sometimes recommended before starting medications that may affect cardiac rhythm.

Early Childhood Inventory-4 — a behavior rating scale for screening psychiatric disorders in children aged 3–5, based on DSM-IV criteria.

Electroencephalogram. A test that records electrical activity in the brain.

A statistical measure of the magnitude of a difference between groups or a relationship between variables.

An estimated Glomerular Filtration Rate below 30 mL/min, indicating severe kidney impairment (Stage 4 CKD). Medications cleared by the kidneys may require dose adjustments or avoidance at this level.

Thoughts, feelings, or behaviors that conflict with a person's self-image or values and are experienced as distressing or unwanted. The concept is clinically important for distinguishing disorders where symptoms are experienced as intrusive (e.g., OCD) from those where they are more ego-syntonic.

Eye Movement Desensitization and Reprocessing; psychotherapy protocol for post-traumatic stress and trauma-related anxiety disorders involving bilateral stimulation (eye movements, tapping, or tones) paired with trauma processing. Mechanism remains debated; efficacy for PTSD is established though equivalent to prolonged exposure.

Difficulty managing emotional responses: quick to anger, easily frustrated, intense reactions.

Mirror-image forms of the same molecule with different pharmacological activity.

Large-scale collaborative neuroimaging studies conducted by the ENIGMA Consortium, which pools brain scan data from thousands of participants worldwide. ENIGMA's ADHD analyses represent the largest brain imaging studies of ADHD to date.

Chemical modifications that change gene expression without altering the DNA sequence itself. Environmental exposures like stress or toxins can create epigenetic changes that affect brain development and may contribute to ADHD risk.

Chemical changes to DNA or its packaging (such as methylation or histone modification) that alter gene activity without changing the DNA sequence itself. Environmental factors (stress, nutrition, toxins) can cause epigenetic changes that influence risk for a range of medical and psychiatric conditions.

Exposure and Response Prevention. The first-line behavioral therapy for OCD, involving gradual confrontation with feared stimuli.

An SSRI antidepressant (Lexapro) widely used for anxiety disorders and depression. Better tolerated than some earlier SSRIs with minimal drug interactions.

The relationship between estrogen levels and dopamine system function. Estrogen enhances dopamine signaling, so hormonal fluctuations across the menstrual cycle, pregnancy, and menopause can influence the severity of any dopamine-related condition, including mood disorders and psychosis.

A stable, reasonably positive mood state — neither manic/hypomanic nor depressed. In bipolar disorder, euthymia refers to the periods between mood episodes. Euthymic periods are clinically important for establishing accurate baselines and making diagnostic distinctions.

A set of cognitive processes including working memory, flexible thinking, and self-control.

A theoretical framework proposing that ADHD-related impairment increases when environmental demands exceed an individual's executive function capacity. Explains why symptoms often worsen during transitions (e.g., middle school, college, new jobs).

A testing accommodation providing additional time to complete assessments.

A medication formulation designed to release its active ingredient gradually over an extended period, typically 8 to 16 hours. Reduces dosing frequency and provides smoother symptom coverage throughout the day.

Outwardly directed behavioral problems including aggression, defiance, and hyperactivity.

The gradual disappearance of a learned behavior when its reinforcement is removed. Typically preceded by an 'extinction burst' where the behavior temporarily intensifies before improving.

Neurobiological process by which the brain learns that a previously feared stimulus is now safe, mediated by ventromedial prefrontal cortex (vmPFC) building a competing safety memory. Forms the core neural mechanism underlying exposure therapy.

A statistical method that identifies clusters of symptoms or test items that tend to co-occur, revealing underlying constructs. Widely used in psychology and psychiatry to determine the dimensional structure of symptom measures.

Free Appropriate Public Education. The legal standard under IDEA requiring schools to provide education tailored to students with disabilities at no cost.

Functional Behavioral Assessment. A systematic process for identifying the function of problem behaviors, used to develop intervention plans.

U.S. Food and Drug Administration. The federal agency responsible for approving medications and medical devices.

A regulatory pathway (510(k)) in which the FDA determines a medical device is substantially equivalent to an existing approved device. FDA clearance is a lower bar than FDA approval and does not require clinical trials demonstrating efficacy. Important distinction when evaluating marketed ADHD diagnostic devices.

Two different levels of FDA regulatory authorization. 'Approved' means the FDA reviewed clinical trial evidence proving safety and efficacy (required for drugs). 'Cleared' means the FDA found a device substantially equivalent to a legally marketed one (lower bar, used for devices like QbTest).

Family Educational Rights and Privacy Act — a U.S. federal law that protects the privacy of student education records. Relevant to ADHD care when coordinating between healthcare providers and schools.

A blood protein that reflects the body's iron stores. Low ferritin levels (even without frank anemia) have been associated with restless legs syndrome, fatigue, cognitive difficulties, and poor sleep. Thresholds for clinical concern vary, but levels below 30 ng/mL are generally considered low.

An elimination diet restricting intake to a small number of low-allergen foods to test whether dietary factors contribute to behavioral or physical symptoms. Highly restrictive and requires careful nutritional supervision, particularly in children.

Few-Foods Diet — see 'Few-Foods Diet.'

Primary evidence-based treatment choice for an anxiety disorder, recommended as the initial intervention based on clinical trial data and treatment guidelines. SSRIs/SNRIs and CBT are first-line for most anxiety disorders; benzodiazepines are not.

The initial processing of an oral drug by the liver before it reaches systemic circulation. Some drugs lose a substantial fraction of their dose during this process, reducing bioavailability.

An SSRI antidepressant (Prozac). Widely used for depression, anxiety, and OCD. A strong CYP2D6 inhibitor relevant to many medication interactions.

An SSRI used primarily for OCD and anxiety disorders. Notable as a strong CYP1A2 and CYP2C19 inhibitor affecting multiple drug metabolic pathways.

Functional Magnetic Resonance Imaging. A neuroimaging technique that measures brain activity by detecting blood flow changes.

Brand name for dexmethylphenidate, the pharmacologically active d-isomer of methylphenidate.

Extended-release dexmethylphenidate using a beaded delivery system.

The first half of the menstrual cycle (from menstruation to ovulation), characterized by rising estrogen levels. Relevant to psychiatry because estrogen influences neurotransmitter function, and many psychiatric symptoms fluctuate across the menstrual cycle.

A neuroimaging measurement from diffusion tensor imaging (DTI) that indicates how organized white matter tracts are. Higher values indicate more organized, intact connections; lower values suggest degraded wiring.

Neural pathways connecting the frontal cortex with the striatum that regulate executive functions including attention, planning, impulse control, and reward processing. Structural and functional differences in these circuits are implicated in a range of neurodevelopmental and psychiatric conditions.

A systematic process for identifying the triggers and consequences maintaining a problem behavior.

The real-world impact of symptoms on daily life, including school, work, relationships, and self-care.

ADHD-related impairment that continues into adulthood even when full diagnostic symptom criteria are no longer met. Highlights that symptom counting alone underestimates the proportion of individuals who continue to struggle.

The question of whether a patient has achieved adequate real-world functioning (work, relationships, daily tasks), not just symptom reduction. A key treatment outcome beyond symptom scores on rating scales.

Gamma-aminobutyric acid. The brain's primary inhibitory neurotransmitter. Reduces neuronal excitability throughout the nervous system. Relevant to ADHD through its role in impulse control circuits and as the target of some medications used for comorbid conditions (anxiety, insomnia).

The overall level of inhibitory signaling from GABA (gamma-aminobutyric acid), the brain's primary inhibitory neurotransmitter. Alterations in GABAergic tone may contribute to the excitatory/inhibitory imbalance hypothesized in ADHD.

Generalized Anxiety Disorder. A condition characterized by persistent, excessive worry across multiple life domains.

Global Assessment of Functioning. A clinician-rated scale of overall psychological, social, and occupational functioning (0-100 scale).

Two ways of summarizing intelligence test results. The Full-Scale IQ (FSIQ) includes all subtests, while the General Ability Index (GAI) excludes processing speed and working memory — domains where ADHD often causes deficits. Using GAI can give a more accurate picture of cognitive ability in individuals with ADHD.

The transfer of skills learned in one setting (e.g., therapy) to other real-world environments.

An anxiety disorder characterized by persistent, excessive worry across multiple life domains.

When an apparent environmental risk factor for a condition actually reflects shared genetic influences. For example, prenatal smoking correlates with ADHD, but this may reflect inherited traits (impulsivity, risk-taking) that both increase smoking likelihood and ADHD risk, rather than a direct causal effect of smoking on the developing brain.

The brain's primary excitatory neurotransmitter. Involved in learning, memory, and synaptic plasticity. Emerging research suggests glutamatergic dysfunction may contribute to ADHD pathophysiology, particularly in cortico-striatal circuits.

A federally funded initiative that provides tools and frameworks (including the Six Core Elements model) for improving healthcare transition from pediatric to adult services. Particularly relevant for ADHD, where transition to adult care is often poorly managed.

A sleep training approach in which parents wait progressively longer intervals before responding to a child's bedtime protests or night wakings. A less abrupt alternative to full extinction ('cry it out'), widely used in pediatric sleep medicine.

The rate of height or weight gain over time, used to monitor potential medication effects on development.

A selective alpha-2A adrenergic agonist used for attention and impulse control disorders, particularly helpful for emotional dysregulation and tics. Extended-release brand name: Intuniv.

Genome-Wide Association Study. A research method scanning entire genomes to find genetic variants associated with a trait or disorder.

Gene-Environment Interaction. The concept that genetic predisposition and environmental factors jointly influence disease expression.

Guanfacine Extended-Release (brand name Intuniv) — a selective alpha-2A adrenergic agonist FDA-approved for ADHD in children and adolescents ages 6–17. A non-stimulant option used as monotherapy or adjunct to stimulants. Requires gradual taper on discontinuation to avoid rebound hypertension.

The time it takes for the body to clear half the drug from the bloodstream. Influences how long a medication remains active, though clinical effects of some drugs can outlast their blood levels.

A measure of how much a factor increases or decreases risk over time.

Hyperpolarization-activated Cyclic Nucleotide-gated channels — ion channels in the brain's prefrontal cortex that regulate neuronal firing. Guanfacine's ADHD benefit is partly attributed to closing HCN channels on prefrontal neurons, strengthening their signaling.

A measure of effect size similar to Cohen's d but corrected for small sample size bias. Commonly used in meta-analyses of ADHD treatment studies to quantify the magnitude of treatment effects.

Healthcare Effectiveness Data and Information Set. A set of quality measures used to evaluate healthcare performance.

A measure of how fast a child is growing in height, expressed as standard deviations from age-matched norms. Used to monitor whether stimulant medications are suppressing growth velocity rather than just absolute height.

Liver damage caused by medications or other substances.

The proportion of variation in a trait that is attributable to genetic differences within a population.

In meta-analysis, the degree of variability in study results beyond what would be expected by chance.

Health Insurance Portability and Accountability Act — a U.S. law that protects patient health information privacy. Relevant to ADHD care when sharing information between providers, schools, and families.

A brain structure essential for memory formation and spatial navigation.

Hierarchical Taxonomy of Psychopathology. A dimensional diagnostic framework that organizes mental health conditions along continuous spectra rather than discrete categories, which may better capture the reality of conditions like ADHD.

Homework, Organization, and Planning Skills — an evidence-based intervention that teaches middle school students with ADHD specific strategies for tracking assignments, organizing materials, and planning ahead.

Hypothalamic-Pituitary-Adrenal axis. The body's central stress response system.

Hypertension — persistently elevated blood pressure. In pediatric patients, defined as blood pressure ≥95th percentile for age, sex, and height on three or more occasions. Relevant to ADHD treatment because stimulants and some non-stimulants can produce small but clinically significant increases in blood pressure.

A state of heightened alertness and scanning for threats.

A state of under-activation in the brain's arousal systems, resulting in reduced alertness, sluggishness, or difficulty maintaining engagement. In arousal theory, hypoarousal drives compensatory stimulation-seeking behavior. The concept is relevant across many conditions including sleep disorders and neurodevelopmental presentations.

Abnormally low blood sodium concentration (below 135 mEq/L). An uncommon but potentially dangerous adverse effect of SSRIs and SNRIs, particularly in elderly patients. Presents with confusion, nausea, headache, and in severe cases seizures.

I-squared — a statistic used in meta-analyses to quantify the percentage of variability in study results that is due to true differences between studies rather than chance. I² = 0% means all studies found essentially the same result; I² > 75% indicates high heterogeneity.

International Classification of Diseases, 11th Revision (2022). The WHO's global diagnostic classification system used in most countries.

Individuals with Disabilities Education Act. Federal law requiring schools to provide free appropriate public education (FAPE) to eligible students with disabilities.

Two U.S. disability laws relevant to ADHD. IDEA (Individuals with Disabilities Education Act) provides special education services through IEPs. The ADA (Americans with Disabilities Act) provides broader civil rights protections and workplace accommodations. Different eligibility criteria and protections apply under each.

Individualized Education Program. A legally binding document under IDEA that provides specialized instruction and services for students with disabilities.

A class of receptors in the brain that respond to imidazoline compounds. Clonidine activates both alpha-2 adrenergic and imidazoline receptors, which may contribute to its sedating properties — a key pharmacological difference from guanfacine.

A tricyclic antidepressant used for depression, anxiety, and nocturnal enuresis. An older medication that has fallen out of favor due to more modern alternatives.

A medication formulation that releases its full dose shortly after ingestion, typically providing 3 to 6 hours of effect. Offers dosing flexibility but requires multiple daily doses for sustained coverage.

The tendency for behavioral interventions to gradually deviate from their original evidence-based protocols over time in real-world settings. A major reason why treatments that work in research trials may show smaller effects in routine clinical practice.

The clinical phenomenon where hyperactive-impulsive ADHD symptoms tend to decrease with age while inattentive symptoms persist or become more prominent, leading to a shift in predominant presentation over development.

The rate of new cases of a condition occurring in a population over a specified time period. Distinct from prevalence, which counts all existing cases regardless of when they began.

An evidence-based group parent training program for families of young children (ages 2–8) with behavior problems, including conduct problems, oppositional behavior, and ADHD. Teaches positive parenting strategies, emotional coaching, and behavior management techniques.

The process by which a patient (or legal guardian) receives and understands information about a proposed treatment's benefits, risks, alternatives, and right to refuse, then voluntarily agrees to proceed. Required before initiating any medication trial.

Two approaches to treating comorbid conditions. Integrated treatment addresses both conditions simultaneously within a unified plan. Sequential treatment stabilizes one condition first, then addresses the other. The choice depends on condition severity and interaction effects.

A neurodevelopmental disorder characterized by significant limitations in intellectual functioning and adaptive behavior.

Inwardly directed emotional problems including anxiety, depression, and withdrawal.

A framework for understanding how overlapping social identities (race, gender, disability, socioeconomic status) interact to create unique experiences of disadvantage or discrimination.

Treatment effects measured on outcomes closely related to the intervention's direct targets (e.g., a homework intervention improving homework completion). Contrasted with distal outcomes like academic achievement, which are influenced by many factors beyond the intervention.

Brand name for extended-release guanfacine, a selective alpha-2A adrenergic agonist. FDA-approved for ADHD as monotherapy and adjunctive to stimulants.

The dose-response relationship where both too little and too much of a neurotransmitter impair function. Optimal performance occurs at intermediate levels.

Incidence Rate Ratio. A measure comparing the rate of events between exposed and unexposed groups in epidemiological studies.

A heightened proneness to anger or frustration, seen across many psychiatric conditions.

Intention-to-Treat analysis. A method analyzing all participants as originally assigned, regardless of adherence or protocol completion.

Delayed-release methylphenidate designed for evening dosing (6:30-9:30 PM). The only stimulant designed for evening administration to provide coverage upon waking.

Knowledge of Attention Deficit Disorders Scale — a validated measure of teachers' and other professionals' knowledge about ADHD, covering symptoms, treatment, and associated features.

Brand name for extended-release clonidine, a non-selective alpha-2 agonist. FDA-approved for ADHD as monotherapy and adjunctive to stimulants.

Key Action Statement — numbered clinical recommendations within the AAP 2019 ADHD Clinical Practice Guideline. KAS 1–4 cover when to evaluate, diagnostic criteria, comorbidity screening, and chronic-condition management respectively.

A measure of how tightly a drug binds to a specific receptor — lower Ki means stronger binding. Comparing Ki values across receptors reveals a medication's selectivity profile (e.g., atomoxetine's Ki of 5 nM for NET vs. 2,300 nM for DAT shows it strongly prefers norepinephrine transporters).

The 'left-handed' mirror-image form of a molecule. The l-enantiomer (levo-) of amphetamine has weaker CNS stimulant effects but contributes more to peripheral cardiovascular effects compared to the d-enantiomer.

An anticonvulsant and mood stabilizer (Lamictal) particularly effective for bipolar depression. Slow titration required to minimize rash risk.

An important distinction in adult ADHD. 'Late-identified' means ADHD was present since childhood but not diagnosed until adulthood. 'Late-onset' would mean ADHD genuinely first appeared in adulthood — a concept that remains controversial and may often reflect late identification.

The l-enantiomer of amphetamine, with more pronounced noradrenergic effects contributing to arousal and cardiovascular tone.

A prodrug of dextroamphetamine that is inactive until metabolized. Provides smoother onset and lower abuse potential. Brand name: Vyvanse.

A mood stabilizer used for bipolar disorder maintenance and acute mania. Narrow therapeutic window requiring regular blood level monitoring.

A research design that follows the same participants over an extended period to track changes and outcomes.

Least Restrictive Environment. The IDEA principle that students with disabilities should be educated with non-disabled peers to the maximum extent appropriate.

The second half of the menstrual cycle (from ovulation to menstruation), characterized by falling estrogen and rising then falling progesterone. Many psychiatric symptoms (mood, anxiety, attention, psychosis) can worsen during the late luteal phase as hormone levels decline.

The ongoing treatment period after initial stabilization, focused on sustaining gains and preventing relapse.

A mood disorder characterized by persistent sad mood or loss of interest, with functional impairment.

Monoamine Oxidase — an enzyme that breaks down monoamine neurotransmitters (dopamine, norepinephrine, serotonin). MAO inhibitors (MAOIs) are contraindicated with stimulants, atomoxetine, and viloxazine due to risk of hypertensive crisis or serotonin syndrome.

Monoamine Oxidase Inhibitor. A class of antidepressant medications rarely used due to dietary restrictions and interaction risks.

Consciously or unconsciously concealing symptoms to appear neurotypical, common in certain populations.

Manifestation Determination Review. A process to determine whether a student's behavior is related to their disability before disciplinary action.

Systematic clinical practice of administering validated patient-reported outcome measures at regular intervals to track symptom trajectory and inform treatment adjustments collaboratively. Components include: measure administration, clinician review, patient-clinician discussion, and documented treatment modification based on symptom progress.

Drugs that permanently inactivate a metabolic enzyme by binding irreversibly to it. Unlike reversible inhibitors, the enzyme cannot recover and must be newly synthesized. Important for predicting drug interaction duration.

A statistical technique that tests whether the relationship between a treatment and an outcome works through a specific intermediate mechanism (mediator). Helps answer 'why' a treatment works, not just 'whether' it works.

The process of returning to normal Medicaid eligibility redeterminations after the COVID-19 pandemic continuous enrollment provision expired. Millions of individuals, including many with ADHD, faced potential loss of coverage and medication access during this transition.

A hormone supplement commonly used to address sleep difficulties associated with psychiatric conditions and medications.

A research method that uses genetic variants as natural experiments to test whether an exposure (like smoking or lead) truly causes an outcome (like ADHD), rather than just correlating with it. Helps distinguish genuine environmental risk factors from genetic confounding.

A statistical method that combines results from multiple studies to produce a more precise estimate of a treatment's effect.

A substance produced when the body chemically processes (metabolizes) a drug or other compound. Metabolites may be active, inactive, or potentially harmful, and their levels can vary depending on individual enzyme activity.

A person's drug-processing capacity based on their genetic enzyme activity (poor, intermediate, normal, ultrarapid).

The ability to think about one's own thinking — to monitor cognitive processes, recognize errors, and adjust strategies accordingly. A core concept in cognitive psychology relevant to learning, therapy (especially CBT), and understanding executive function deficits across many conditions.

Extended-release methylphenidate using a beaded system with a 30:70 immediate-to-delayed release ratio.

A stimulant medication that enhances attention and executive function by blocking the reuptake of dopamine and norepinephrine. Brand names include Ritalin, Concerta, Focalin, and Daytrana.

Motivational Interviewing — a collaborative, person-centered counseling approach that helps individuals explore and resolve ambivalence about behavior change. Used in ADHD care to improve treatment engagement and medication adherence.

An estimate of a child's expected adult height based on the average of both parents' heights (with a sex adjustment). Used when monitoring stimulant effects on growth to determine whether a child is tracking toward their genetic height potential.

A formulation combining d-amphetamine and l-amphetamine in a 3:1 ratio. Brand name: Adderall.

A wakefulness-promoting agent sometimes used off-label for attention disorders and excessive daytime sleepiness.

Statistical tests examining whether a treatment works differently for different subgroups of patients (e.g., does behavioral therapy work better for younger vs. older children?). Helps identify which patients benefit most from which treatments.

A change to what a student is expected to learn or demonstrate, altering content or performance standards. Contrast with accommodation, which changes how material is delivered without altering expectations.

Therapeutic approach using motivational interviewing techniques to increase client intrinsic motivation for behavior change and treatment adherence. Involves exploring ambivalence, eliciting change talk, and supporting autonomy rather than directive advice-giving.

A collaborative conversation style that strengthens a person's own motivation for and commitment to change.

Involuntary movement in muscles not directly involved in a voluntary action (e.g., one hand mirroring the other during fine motor tasks). A soft neurological sign that may support ADHD diagnosis in young children, reflecting immature motor system development.

Multimodal Treatment Study of Children with ADHD. A landmark NIMH-funded trial comparing medication, behavioral therapy, combined treatment, and standard care.

Multi-Tiered Systems of Support. A framework providing increasingly intensive interventions based on student needs.

Gathering diagnostic information from multiple sources to improve accuracy.

Triple-bead extended-release mixed amphetamine salts. The longest-acting oral amphetamine formulation, with duration up to 16 hours.

A rating scale designed to measure symptoms of a specific disorder.

Two categories of behavioral rating scales. Broadband instruments (like the CBCL) screen across many behavioral domains to identify multiple possible problems. Narrowband instruments (like the ADHD-RS) focus specifically on one condition with greater diagnostic precision.

Noradrenergic and Specific Serotonergic Antidepressant. A drug class represented by mirtazapine, which blocks alpha-2 autoreceptors and specific serotonin receptors (5-HT2A, 5-HT2C, 5-HT3) to enhance norepinephrine and serotonin transmission.

Whether skills learned in one context generalize. Near-transfer means improvement on tasks very similar to the training task (e.g., working memory training improving working memory scores). Far-transfer means improvement on unrelated real-world outcomes (e.g., working memory training improving academic performance). Most cognitive training shows near-transfer but limited far-transfer.

The probability that a negative test result correctly identifies someone who does not have the condition.

A set of symptoms (irritability, feeding difficulties, respiratory distress, jitteriness) that some newborns develop in the first days of life after in utero exposure to certain psychiatric medications. Usually mild and self-limited, resolving within days.

Norepinephrine Transporter. The protein that recycles norepinephrine from the synapse. Blocked by both stimulants and some non-stimulants.

A drug that blocks the norepinephrine transporter, preventing norepinephrine from being reabsorbed back into nerve terminals. Atomoxetine and viloxazine are NET inhibitors used in ADHD treatment.

A method that compares multiple treatments simultaneously by linking all available trials.

A category of conditions with onset during the developmental period, arising from differences in brain maturation. Includes ADHD, autism, intellectual disability, and learning disorders.

The pattern of brain maturation and cognitive development from early childhood through young adulthood.

The brain's ability to reorganize and form new neural connections throughout life in response to experience.

Natural steroid hormones produced by the body (particularly allopregnanolone from progesterone metabolism) that modulate extrasynaptic GABA-A receptors, providing baseline neural inhibition independent of synaptic transmission. Zuranolone, an oral synthetic neurosteroid, FDA-approved for postpartum depression, demonstrates mechanism distinct from benzodiazepines.

A chemical messenger released by neurons to transmit signals across synapses. The neurotransmitters most relevant to ADHD are dopamine and norepinephrine (catecholamines), which regulate prefrontal cortex function, reward processing, and attention.

New Forest Parenting Programme — a behavioral parent training program specifically designed for preschool-age children (3–5) with ADHD. Targets ADHD-specific executive function deficits through structured parent-mediated activities. Supported by RCT evidence as a first-line intervention for preschool ADHD.

National Institute for Health and Care Excellence (UK). Publishes evidence-based guidance for mental health and neurodevelopmental disorder management.

The UK National Institute for Health and Care Excellence guideline for ADHD (NG87), published in 2018 and regularly updated. A widely referenced international clinical guideline for ADHD diagnosis and management across the lifespan.

National Institute of Mental Health. The lead U.S. federal agency for research on mental disorders.

Network Meta-Analysis — a statistical method that simultaneously compares multiple treatments by combining direct (head-to-head) and indirect evidence across a network of trials. The Cortese et al. (2018) Lancet Psychiatry NMA of ADHD medications is a landmark example, comparing efficacy and tolerability across stimulants and non-stimulants.

Number Needed to Harm — the number of patients who must be treated with an intervention before one additional patient experiences a specific adverse outcome compared to a control group. Lower NNH values indicate more frequent harm. The inverse of the absolute risk increase.

Number Needed to Treat — the number of patients who must be treated with an intervention for one additional patient to achieve a beneficial outcome compared to a control group. Lower NNT values indicate more effective treatments. For ADHD stimulants, the NNT for clinically significant response is approximately 2-3, among the lowest in psychiatry.

Failure to follow a prescribed treatment regimen, whether by missing doses, stopping medication early, or not attending therapy sessions. Common in ADHD and associated with poorer outcomes. Often driven by side effects, forgetfulness, stigma, or cost.

A medication used to treat ADHD that does not belong to the stimulant class. Includes atomoxetine, guanfacine, clonidine, and viloxazine. Often considered when stimulants are ineffective, poorly tolerated, or contraindicated.

A neurotransmitter involved in attention, arousal, and the stress response. Key pathway: locus coeruleus → widespread cortical projections, especially prefrontal cortex. Strengthens signal in PFC networks by acting on α2A-adrenoceptors. Targeted by atomoxetine, guanfacine, and clonidine. Under high stress, excess norepinephrine activates α1 receptors that degrade PFC function.

Cutoff scores on standardized tests that are set based on the distribution of scores in a reference population. For example, a T-score of 65 means 1.5 standard deviations above the population mean, placing the individual approximately at the 93rd percentile.

A tricyclic antidepressant used for depression, anxiety, and chronic pain conditions. Metabolite of amitriptyline with improved side effect profile.

Relating to the classification of diseases and disorders. A nosological question asks whether a condition belongs in the diagnostic system as its own distinct entity.

Negative Predictive Value — the probability that a person with a negative screening result truly does not have the condition.

A group of genes (NCAM1, TTC12, ANKK1, DRD2) located near each other on chromosome 11 that are involved in dopamine signaling. Genetic variation in this cluster has been associated with ADHD and substance use risk.

The brain's reward center, which drives motivation and is central to understanding reward processing and motivation across conditions.

A sleep disorder where the airway repeatedly collapses during sleep, causing fragmented sleep and daytime impairment.

Obsessive-Compulsive Disorder. A condition involving intrusive thoughts (obsessions) and repetitive behaviors (compulsions).

Office for Civil Rights — the division of the U.S. Department of Education that enforces Section 504 of the Rehabilitation Act, which provides accommodations for students with disabilities including ADHD.

Oppositional Defiant Disorder — a behavioral disorder characterized by a persistent pattern of angry/irritable mood, argumentative/defiant behavior, or vindictiveness. One of the most common comorbidities with ADHD, occurring in approximately 40-60% of children with ADHD.

A measure of association between an exposure and an outcome, commonly used in case-control studies.

Prescribing an FDA-approved medication for a condition, age group, or dose not specified in its official labeling.

Other Health Impairment. An IDEA eligibility category for students whose health conditions—including heightened alertness to environmental stimuli—adversely affect educational performance.

An atypical antipsychotic (Zyprexa) used for bipolar disorder and psychosis. Higher metabolic risk (weight gain, diabetes) than some other antipsychotics.

Another term for a few-foods elimination diet — a highly restricted diet limited to foods unlikely to trigger immune or behavioral reactions. Used in research protocols to test whether specific foods contribute to symptoms.

A study design in which both the researcher and participant know which treatment is being administered. Useful for assessing real-world tolerability and long-term safety but more vulnerable to expectancy bias than blinded designs.

A learning process where the likelihood of a behavior changes based on its consequences—increasing with reinforcement and decreasing with punishment.

A behavioral disorder characterized by a pattern of angry/irritable mood, argumentative behavior, and defiance toward authority figures.

A prefrontal region involved in decision-making, reward evaluation, and social behavior.

Osmotic-Release Oral System — see 'OROS technology.'

Osmotic-controlled Release Oral delivery System — the drug delivery mechanism used in Concerta (methylphenidate ER). Uses osmotic pressure to release medication at a controlled rate, producing an ascending plasma profile that mimics twice-daily immediate-release dosing.

A drug delivery technology (used in OROS methylphenidate) that uses an osmotic gradient to push medication through a laser-drilled hole in an outer shell, producing a controlled ascending release profile over 10 to 12 hours.

Organizational Skills Training. A structured intervention teaching children and adolescents to manage materials, time, and task planning.

Organization, Time Management, and Planning — a category of executive function skills frequently impaired in ADHD. Interventions targeting OTMP deficits focus on concrete skill-building rather than symptom reduction alone.

An SSRI antidepressant (Paxil) with notable strong CYP2D6 inhibitor properties, affecting metabolism of many other medications. Used for anxiety and depression.

A developmental model (Loeber & colleagues) describing three trajectories toward serious conduct problems: the Authority Conflict Pathway (defiance → disobedience), the Covert Pathway (lying → property crimes), and the Overt Pathway (aggression → violence). Helps predict which children with ADHD are at highest risk.

Preschool ADHD Treatment Study. A landmark NIH trial evaluating medication treatment in preschool-age children.

Probably-blind raters — assessors in clinical trials who are not formally blinded but have no direct knowledge of treatment assignment. Used when full blinding is impractical, though this introduces more bias risk than true blinding.

Parent-Child Interaction Therapy — an evidence-based treatment for young children (ages 2–7) with disruptive behavior. A therapist coaches parents in real-time through an earpiece while they interact with their child.

Pathological Demand Avoidance — a behavioral profile, often discussed in the context of autism, characterized by extreme avoidance of everyday demands and expectations. May co-occur with or be mistaken for ADHD.

Prescription Drug Monitoring Program. A state database tracking controlled substance prescriptions to prevent misuse.

Prolonged Exposure therapy — an evidence-based treatment for PTSD that involves gradually confronting trauma-related memories and situations in a safe, structured way.

Pediatric ACEs and Related Life-Events Screener — a validated screening tool for adverse childhood experiences designed for use in pediatric primary care settings.

The commonly cited observation that stimulant medications appear to have a 'calming' effect in children with ADHD, which seems paradoxical given their stimulant classification. The effect is not actually paradoxical or unique to children — stimulants improve prefrontal cortex function and self-regulation in both children and adults with ADHD.

Pediatric Quality of Life Inventory. A measure of health-related quality of life in children and adolescents.

A model distinguishing between skill deficits (the child doesn't know how) and performance deficits (the child knows how but doesn't consistently do it). ADHD primarily causes performance deficits — the child has the skill but fails to deploy it reliably in the moment.

Prefrontal cortex. The anterior region of the frontal lobe responsible for executive functions including sustained attention, working memory, behavioral inhibition, planning, and organization. Exquisitely sensitive to catecholamine levels, following an inverted-U dose-response curve.

Reduced activity in the prefrontal cortex, the brain region responsible for executive functions including attention control, planning, and impulse regulation. One of the most well-established neuroimaging findings in ADHD.

Insurance provider directories that list practitioners who are not actually accepting new patients, have left the network, or have incorrect contact information. A significant barrier to accessing ADHD care, particularly for Medicaid enrollees.

How a drug affects the body, including its mechanism of action and therapeutic effects.

How a person's genetic makeup affects the way their body processes a drug.

Two types of genetic testing relevant to medication management. Pharmacokinetic testing examines genes (like CYP2D6) that affect how the body processes a drug. Pharmacodynamic testing examines genes (like receptors) that affect how the body responds to a drug.

How the body absorbs, distributes, metabolizes, and eliminates a drug. Determines how long and how strongly a medication works.

Brief, burst-like dopamine release that signals prediction errors and drives learning and reinforcement.

When a drug interaction changes a person's metabolizer status (e.g., converting a normal metabolizer to a functional poor metabolizer).

A presentation that looks identical to a disorder from the outside but has a different underlying cause.

The observable characteristics of an individual resulting from the interaction of genotype and environment. In clinical use, the pattern of symptoms and traits a person displays.

The ability to recognize and manipulate the sound structure of language. Deficits in phonological processing are the core feature of dyslexia and a major area of assessment in any evaluation of reading difficulties.

Patient Health Questionnaire-9. A brief screening and severity measure for depression.

Patient Health Questionnaire for Adolescents — a depression screening tool adapted for adolescent populations. Used in ADHD evaluations to screen for comorbid depression, which co-occurs in approximately 14–20% of youth with ADHD.

Present Levels of Academic Achievement and Functional Performance. The IEP section documenting a student's current abilities and needs.

An inert substance or sham intervention administered in clinical trials to serve as a comparison against the active treatment. Allows researchers to distinguish true drug effects from psychological or contextual influences.

An improvement in symptoms attributable to the expectation of benefit rather than the treatment's specific mechanism.

Periodic Limb Movement Disorder — repetitive, involuntary leg movements during sleep that can fragment sleep and mimic or worsen ADHD symptoms. Should be considered in the differential diagnosis when a child with ADHD has restless sleep.

The cumulative genetic risk from many common gene variants, each contributing a small effect. ADHD is highly polygenic — hundreds of gene variants each slightly increase risk, and their combined effect substantially influences ADHD liability.

A numerical summary of genetic risk for a condition based on the cumulative effect of multiple common gene variants.

An overnight sleep study that monitors breathing, oxygen levels, and brain activity during sleep.

Individuals who carry genetic variants causing reduced or absent activity of a specific drug-metabolizing enzyme. Poor metabolizers of CYP2D6, for example, clear atomoxetine much more slowly, requiring lower doses to avoid side effects.

The probability that a positive test result correctly identifies someone who has the condition.

Positive Predictive Value — the probability that a person with a positive screening result truly has the condition. Depends heavily on the base rate of the condition in the population being tested.

The brain region behind the forehead responsible for attention, planning, working memory, and impulse control. Central to understanding many psychiatric conditions.

Uncomfortable sensory experiences that precede tic execution in Tourette syndrome — often described as an 'itch' or 'pressure' that is temporarily relieved by performing the tic. The target of behavioral interventions like CBIT.

An automatic, reflexive behavioral response that occurs before conscious decision-making, such as blurting out an answer, grabbing an object, or interrupting a conversation. Suppressing prepotent responses requires intact behavioral inhibition.

The tendency to continue an unchanged medication regimen despite evidence that adjustment is needed.

The DSM-5 relabeling of disorder "subtypes" to "presentations", reflecting that they are fluid and can change over time.

The proportion of a population found to have a condition at a specific point in time (point prevalence) or over a defined period (period prevalence). Distinct from incidence, which counts new cases only.

Pro re nata (as needed). A dosing strategy where medication is taken only when symptoms arise rather than on a fixed schedule. Common for acute anxiety management with benzodiazepines or hydroxyzine.

A pharmacologically inactive (or minimally active) compound that must be metabolized in the body to release the active drug.

A statistical technique that creates balanced comparison groups by matching treated and untreated participants on relevant characteristics.

A statistical method that creates more comparable groups in observational studies by matching or weighting participants based on their likelihood of receiving treatment, reducing confounding bias when randomized trials are not feasible.

A study design that follows a defined group forward in time to observe outcomes.

The use of external tools and supports (lists, timers, phone reminders, visual schedules) as substitutes for impaired internal working memory in ADHD. The term emphasizes that these are not mere conveniences but functional replacements for a cognitive deficit.

The behavioral principle that interventions are more effective when consequences (rewards or corrections) are delivered closer in time and space to the target behavior. Explains why classroom-based interventions often outperform clinic-based ones for ADHD.

Polygenic Risk Score. A numerical summary of genetic risk for a condition based on the cumulative effect of multiple common gene variants.

Apparent treatment failure that is actually caused by non-adherence, untreated comorbidities, or pharmacokinetic mismatch.

Sympathomimetic decongestant available over the counter that can trigger or worsen anxiety symptoms through noradrenergic activation. Important to screen for in patients presenting with new or worsening anxiety, particularly panic-like symptoms.

Polysomnography — an overnight sleep study that records brain waves (EEG), eye movements, muscle activity, heart rhythm, and breathing during sleep. The gold standard for diagnosing obstructive sleep apnea, which mimics ADHD in children at rates 10× the general population.

Providing patients and families with information about a diagnosis, its treatment, and management strategies.

A structured academic and cognitive evaluation designed to identify specific learning disabilities.

Observable restlessness with purposeless or semi-purposeless motor activity driven by inner tension. Distinguished from akathisia (which is specifically medication-induced) and from anxiety-driven fidgeting.

A slowing of thought processes, speech, and physical movement. A cardinal feature of severe depressive episodes and also seen in some neurological and medical conditions. Can affect cognitive testing results and clinical presentation.

Post-Traumatic Stress Disorder. A condition that can develop after exposure to traumatic events.

A deep brain structure involved in motor control and habit learning.

A computer-based test that simultaneously measures attention, impulsivity, and motor activity using infrared tracking of head movements during a continuous performance task. FDA-cleared as an aid (not a standalone diagnostic tool) in ADHD evaluation.

Brand name for viloxazine extended-release, the newest FDA-approved non-stimulant for ADHD. A norepinephrine reuptake inhibitor with serotonin-modulating properties.

Corrected QT interval. A measurement on ECG related to heart rhythm. Prolongation is a safety concern with some medications.

Abnormal lengthening of the heart's electrical recovery interval, increasing risk of dangerous arrhythmias.

An atypical antipsychotic (Seroquel) used for bipolar disorder, psychosis, and as a sleep aid due to sedating properties. Lower risk of extrapyramidal side effects.

Extended-release methylphenidate in liquid suspension. One of the few stimulant formulations available for patients who cannot swallow pills.

Relative Age Effect — see 'Relative Age Effect.'

A study design in which participants are randomly assigned to receive either the experimental intervention or a control condition. Considered the gold standard for evaluating treatment efficacy because randomization minimizes selection bias.

A study design where patients who have responded well to a medication are randomly assigned to either continue or switch to placebo. Used to demonstrate ongoing treatment benefit and separate true drug effect from placebo response.

The ability to quickly name familiar visual items (letters, numbers, colors, objects) presented in sequence. Slow rapid automatized naming is a marker of reading difficulties and is commonly impaired in children with comorbid ADHD and dyslexia.

Randomized Controlled Trial — a study design in which participants are randomly assigned to receive either the intervention or a control (placebo or active comparator). Considered the gold standard for evaluating treatment efficacy because randomization minimizes confounding variables.

A temporary flare of symptoms that are more intense than the person's unmedicated baseline, occurring as a medication wears off.

A temporary worsening of ADHD symptoms (irritability, hyperactivity, emotional lability) that occurs as stimulant medication wears off, sometimes to levels worse than the untreated baseline. Distinct from the underlying ADHD symptoms simply re-emerging.

The practice of delaying a child's school entry by one year so they are older than classmates. Relevant to ADHD because the Relative Age Effect shows that younger children in a grade are disproportionately diagnosed with ADHD, raising questions about maturity being mistaken for pathology.

An intense emotional response to perceived or actual rejection, criticism, or failure that is disproportionate to the situation. Studied across multiple conditions including ADHD, borderline personality disorder, social anxiety disorder, and depression.

The return of symptoms after a period of improvement or remission.

A pattern of illness with alternating periods of active symptoms (relapses) and periods of improvement or recovery (remissions). Describes the ADHD trajectory in some individuals, where symptoms fluctuate rather than being continuously present.

The finding that children who are young for their grade (born just before the enrollment cutoff) are significantly more likely to be diagnosed with ADHD and prescribed stimulants than older classmates — likely because normal developmental immaturity is misinterpreted as pathology.

The percentage of a mother's weight-adjusted medication dose that a breastfed infant receives through breast milk. An RID below 10% is generally considered compatible with breastfeeding for most medications.

A sustained period where symptoms fall below clinical thresholds and functional impairment is minimal.

A behavioral technique where a privilege or token is removed following an undesired behavior.

Three levels of treatment outcome. Response means meaningful symptom improvement (often defined as ≥25–30% reduction on rating scales). Remission means symptom levels have fallen below diagnostic thresholds. Functional remission means the person is functioning well in daily life — the most meaningful but hardest to achieve.

A brain imaging technique that measures spontaneous neural activity patterns when a person is not performing any specific task. Used widely in neuroscience and psychiatry research to map functional connectivity between brain networks.

A neurological condition causing uncomfortable sensations and an urge to move the legs.

The process by which a presynaptic neuron recycles neurotransmitters from the synapse back into the cell.

A drug that blocks the transporter proteins responsible for recycling neurotransmitters, keeping them active in the synapse longer.

How rewarding or motivating the brain perceives a given task or stimulus to be.

Relative Infant Dose — see 'Relative infant dose.'

The ratio of event probability in the exposed group to the unexposed group.

An atypical antipsychotic used for irritability, aggression, and psychotic symptoms across psychiatric conditions. Lower propensity for metabolic side effects than older antipsychotics.

Brand name for immediate-release methylphenidate. Duration approximately 3-5 hours, requiring multiple daily doses.

Extended-release methylphenidate using a multi-particulate beaded system with a 50:50 immediate-to-delayed release ratio.

Restless Legs Syndrome — an uncomfortable urge to move the legs, typically worse at rest and in the evening. Common in ADHD and may disrupt sleep, worsening daytime ADHD symptoms. Often associated with low iron/ferritin levels.

The gold-standard framework in psychiatry for establishing whether a diagnosis is scientifically valid. The five criteria are: consistent clinical presentation across settings and cultures, familial aggregation, laboratory correlates, predictable course, and treatment response.

Response to Intervention. A multi-tiered approach to early identification and support of students with learning and behavior needs.

Repetitive Transcranial Magnetic Stimulation; neuromodulation technique applying magnetic pulses to scalp to modulate brain activity, typically targeting dorsolateral prefrontal cortex. FDA-approved for treatment-resistant depression; efficacy in anxiety disorders remains investigational with mixed results.

Right Upper Quadrant — an anatomical region of the abdomen overlying the liver. RUQ tenderness or pain is monitored during atomoxetine treatment because of the rare but serious risk of hepatotoxicity (severe liver injury occurs in approximately 1 in 500,000 patient-years).

A U.S. federal law (2008) that originally required at least one in-person evaluation before prescribing controlled substances via telemedicine. Temporary flexibilities during COVID-19 allowed telehealth prescribing of stimulants, but the long-term regulatory status remains in flux.

An evidence-based CBT program for adult ADHD developed by Safren and Sprich at Massachusetts General Hospital. Targets core functional impairments (organization, distractibility, cognitive distortions) rather than ADHD symptoms directly.

Substance Abuse and Mental Health Services Administration — a U.S. federal agency that provides guidance, data, and resources on substance use and mental health. Referenced in ADHD context regarding substance use disorder screening and treatment integration.

A pharmacokinetic property where an enzyme responsible for converting a prodrug to its active form reaches maximum capacity at a certain dose, preventing further increases in active drug levels even with higher doses. A safety feature of lisdexamfetamine.

External support structures that compensate for symptoms. When scaffolding is removed, symptoms become more apparent.

Support from the environment (structure, routines, reminders, close supervision) that compensates for executive function deficits and masks ADHD impairment. When scaffolding is removed (e.g., leaving home for college), previously hidden deficits become apparent.

The loss of external supports that were compensating for ADHD deficits, often occurring at developmental transitions (starting college, first job, living independently). Frequently triggers first-time ADHD diagnosis in adolescents and adults.

Screen for Child Anxiety Related Disorders — a 41-item child and parent self-report instrument that screens for anxiety disorders in children ages 8–18. Recommended alongside the Vanderbilt in ADHD evaluations because the Vanderbilt's anxiety subscale has poor sensitivity (~0.37), missing approximately 63% of truly anxious children.

Society of Clinical Child and Adolescent Psychology (APA Division 53) — the professional organization that maintains an evidence-based treatment classification system rating psychological interventions for children and adolescents.

A DEA classification for drugs with high abuse potential but accepted medical use, requiring special prescribing controls.

The DEA classification for drugs with accepted medical use but high potential for abuse and severe dependence. Stimulant ADHD medications (methylphenidate, amphetamines) are Schedule II, which imposes strict prescribing, dispensing, and manufacturing rules.

Shared Decision-Making — a collaborative process in which clinicians and patients jointly make treatment decisions, incorporating both clinical evidence and patient preferences and values.

Alternative evidence-based treatment for an anxiety disorder when first-line interventions have been inadequately trialed or failed. Examples include buspirone augmentation, alternative SSRI/SNRI agents, or specific psychotherapy protocols for particular presentations.

Selective MAO-B inhibitor at low doses (used for Parkinson's disease) that becomes a non-selective MAOI at higher doses. The transdermal patch (Emsam) bypasses dietary tyramine restrictions at the lowest dose, offering a theoretically safer MAOI option.

The theory that individuals with untreated ADHD may use substances (nicotine, cannabis, alcohol, caffeine) to manage their symptoms — seeking stimulation for under-arousal or relief from emotional dysregulation. Supported by findings that earlier ADHD treatment reduces later substance use risk.

The ability of a test to correctly identify those who have a condition (true positive rate).

Exaggerated behavioral or emotional responses to ordinary sensory input (sounds, textures, lights). Common in autism and sometimes present in ADHD, potentially complicating treatment compliance and daily functioning.

Excessive fear or worry about being separated from attachment figures.

A neurotransmitter involved in mood regulation, anxiety, impulse control, and sleep. Key pathway: raphe nuclei → widespread projections throughout the cortex, limbic system, and brainstem. Primary target of SSRIs and SNRIs. Relevant to ADHD through comorbid mood and anxiety disorders.

A potentially life-threatening condition caused by excessive serotonin activity, characterized by agitation, rapid heart rate, fever, muscle rigidity, and clonus.

Serotonin reuptake transporter, the membrane protein that SSRIs and SNRIs target to block reuptake of serotonin from synaptic space back into presynaptic neurons, increasing serotonin availability. The 5-HTTLPR polymorphism in the gene encoding SERT has no validated clinical utility despite earlier candidate gene claims.

An SSRI antidepressant (Zoloft) commonly used for anxiety disorders, depression, OCD, and PTSD across age groups.

A clinical trial where the control group receives a convincing but inactive version of the treatment (e.g., a device that looks and feels like the real one but delivers no active intervention). The equivalent of a placebo control for device or procedural studies.

A persistent pattern of negative self-perception (e.g., 'I'm lazy,' 'I'm stupid') that develops from years of ADHD-related failures, criticism, and frustration — often before diagnosis. Addressing these internalized beliefs is an important component of ADHD psychotherapy.

A collaborative process where clinicians and patients jointly make treatment decisions.

Syndrome of Inappropriate Antidiuretic Hormone secretion. A potentially serious adverse effect of SSRIs and SNRIs causing dilutional hyponatremia; risk is highest in elderly patients and those on diuretics.

A research design that compares siblings who differ in exposure (e.g., one sibling took medication, the other didn't) to control for shared genetic and family environmental factors. Provides stronger causal evidence than comparing unrelated individuals.

In neuroscience, the clarity of relevant neural signals relative to background neural activity.

A framework from Got Transition for organizing healthcare transition: (1) transition policy, (2) transition tracking, (3) transition readiness, (4) transition planning, (5) transfer of care, (6) transfer completion. Applied to ADHD patients transitioning from pediatric to adult care.

Specific Learning Disorder. A neurodevelopmental disorder affecting the acquisition of academic skills despite adequate instruction.

The normal cycling through light sleep, deep sleep, and REM sleep throughout the night.

The time it takes to transition from full wakefulness to sleep after lights out. Prolonged sleep onset latency is a common side effect of stimulant medications and a frequent concern in ADHD management.

Sequential Multiple Assignment Randomized Trial. A study design that adapts treatment based on patient response at each stage.

Standardized Mean Difference — an effect size statistic that expresses the difference between two group means in standard deviation units, allowing comparison across studies using different outcome scales. Conventional benchmarks: 0.2 = small, 0.5 = medium, 0.8 = large. Cohen's d and Hedges' g are common variants.

Swanson, Nolan, and Pelham Rating Scale, Version IV. A widely used symptom rating scale based on DSM criteria.

Serotonin-Norepinephrine Modulating Agent — a regulatory marketing designation (coined by Supernus Pharmaceuticals) for viloxazine, describing its combined norepinephrine reuptake inhibition and serotonin receptor modulation. Not an established independent pharmacological class.

Single Nucleotide Polymorphism — a variation in a single DNA base pair at a specific position in the genome. ADHD's heritability is substantially polygenic, with genome-wide association studies identifying multiple SNPs of small individual effect that collectively account for roughly 22% of ADHD's phenotypic variance.

The proportion of trait variation explained by common single-nucleotide polymorphisms (single-letter DNA changes) measured across the genome. For ADHD, SNP-based heritability is about 22%, lower than twin-study heritability (~74%) because it only captures common variants.

Serotonin-Norepinephrine Reuptake Inhibitor. A class of antidepressants that block reuptake of both serotonin and norepinephrine.

An anxiety disorder characterized by intense fear of social situations and scrutiny by others.

The natural back-and-forth flow of social interaction — taking turns in conversation, responding to social cues, and sharing emotional experiences. Deficits in social reciprocity are a hallmark of autism spectrum disorder and are also assessed in other developmental and psychiatric evaluations.

A meta-cognitive therapy program for adult ADHD developed by Mary Solanto. Focuses on building time management, organization, and planning skills through structured group sessions with concrete skill practice.

Excessive physical tension, restlessness, and body-based anxiety symptoms (racing heart, muscle tension, stomach distress). A prominent feature of generalized anxiety disorder, panic disorder, and PTSD, and an important treatment target in its own right.

A dual-pathway model of ADHD proposing that ADHD symptoms arise from two distinct neurocognitive pathways: an executive function deficit pathway (involving prefrontal circuits) and a motivational/reward pathway (involving ventral striatal circuits). Later expanded to include temporal processing as a third pathway.

A neurodevelopmental disorder affecting the acquisition of academic skills despite adequate instruction.

The ability of a test to correctly identify those who do not have a condition (true negative rate).

Selective Serotonin Reuptake Inhibitor. A class of antidepressant medications commonly used for anxiety and depression.

A phenomenon where starting an SSRI antidepressant can initially increase anxiety, restlessness, or agitation — particularly in youth. Typically transient (resolving within 1–2 weeks) but important to distinguish from true symptom worsening or emerging suicidality.

Blood pressure classifications in children. Stage 1 hypertension is ≥95th percentile or ≥130/80 mmHg in adolescents. Stage 2 is ≥95th percentile + 12 mmHg or ≥140/90 mmHg. Relevant to stimulant monitoring, as these medications can modestly raise blood pressure.

Supporting Teens' Autonomy Daily — a behavioral intervention program designed to build organizational and self-management skills in adolescents with ADHD.

Sequenced Treatment Alternatives to Relieve Depression. Landmark NIMH-funded trial (N=4,041) demonstrating that most patients require multiple treatment steps to achieve remission, with diminishing response rates at each step.

The point where the drug level in the blood stabilizes, meaning you can judge whether a dose is working. Reached after about 5 half-lives.

The point at which a medication's rate of intake equals its rate of elimination, resulting in stable blood levels. Most medications reach steady-state after about 4-5 half-lives of consistent dosing. Important for interpreting medication effects and side effects.

Treatment matching framework where intensity and invasiveness increase stepwise based on symptom severity and treatment response. Lower-intensity steps (psychoeducation, self-help) are offered first; progression to higher-intensity steps (full psychotherapy, medication) occurs only if lower steps prove insufficient.

A structured assessment strategy that proceeds through increasingly detailed evaluation stages: initial screening, followed by clinical interview, then rating scales, and targeted testing as needed — rather than performing all assessments at once.

A rare, severe skin reaction to medications requiring immediate medical attention.

A class of medications (methylphenidate and amphetamine formulations) that increase synaptic dopamine and norepinephrine by blocking reuptake transporters (DAT and NET). First-line pharmacotherapy for ADHD with the largest evidence base for efficacy.

A DSM-5 diagnosis for problematic use of stimulant substances (cocaine, amphetamines) characterized by impaired control, social impairment, risky use, and pharmacological indicators. Distinct from appropriate therapeutic use of prescribed stimulant medications for ADHD.

Describes a patient who has never previously taken stimulant medication. Relevant to treatment planning because stimulant-naïve patients may be more sensitive to medication effects and side effects, often requiring lower starting doses.

Brand name for atomoxetine, a selective norepinephrine reuptake inhibitor (NRI). The first FDA-approved non-stimulant for ADHD. Not a controlled substance.

A deep brain structure involved in reward, motivation, and habit formation. Includes the caudate nucleus and putamen.

Medications that are primarily metabolized by a single enzyme pathway. When that enzyme is inhibited, blood levels of strong substrates can rise dramatically — making them particularly vulnerable to drug-drug interactions.

An advanced statistical technique that tests complex relationships among multiple variables simultaneously, including both direct and indirect (mediated) effects. Widely used in psychology, psychiatry, and epidemiology to model how multiple factors interact.

A standardized assessment format where clinicians ask predetermined questions in a specific order to improve diagnostic reliability.

Symptoms that are present but do not meet the full number, duration, or severity criteria required for a formal diagnosis. Clinically significant because sub-threshold ADHD symptoms can still cause meaningful impairment and may warrant monitoring or intervention.

The measured sizes of deep brain structures (caudate, putamen, nucleus accumbens, amygdala, hippocampus) as determined by MRI. ENIGMA consortium studies have shown small but reliable reductions in several subcortical volumes in individuals with ADHD.

A behavioral technique (also called shaping) where complex target behaviors are broken into smaller steps, and each step closer to the goal is reinforced. Used in ADHD behavioral interventions to build skills gradually without overwhelming the child.

Substance Use Disorder — a diagnostic category encompassing problematic patterns of substance use leading to clinically significant impairment or distress. ADHD significantly increases SUD risk (approximately 1.5-3× elevated), making SUD comorbidity a critical consideration in stimulant prescribing decisions.

Thoughts about or preoccupation with ending one's own life, ranging from passive wishes to active planning.

Medication doses that exceed the recommended therapeutic range. Studied in abuse liability research to determine whether a medication produces euphoria or reinforcing effects at high doses.

A medication formulation that delivers its active ingredient at a controlled rate over a prolonged period, similar to extended-release. Often used interchangeably with extended-release in clinical literature.

A drug that stimulates the sympathetic nervous system (fight-or-flight response).

The discrepancy between symptom severity scores and real-world functioning. A patient may show improved rating scale scores but still struggle with daily tasks — or conversely, may report high symptom levels while functioning adequately. Treatment should target both symptoms and function.

The junction between two neurons where chemical signals (neurotransmitters) are transmitted across a tiny gap from the sending cell to the receiving cell.

The amount of neurotransmitter present in the synapse and available to bind receptors.

ADHD that continues to meet full diagnostic criteria in adulthood (all required symptoms present). Contrasted with symptomatically persistent (some symptoms remain but below diagnostic threshold) and functionally persistent (symptoms cause ongoing impairment regardless of formal criteria).

Involuntary mirror movements — when performing a voluntary movement with one hand, the other hand involuntarily mimics it. A soft neurological sign seen in young children with ADHD that reflects immature motor circuit development.

A comprehensive, structured synthesis of all available evidence on a specific clinical question.

A standard score on norm-referenced rating scales where 50 is the population mean and each 10 points equals one standard deviation. A T-score of 65 is 1.5 standard deviations above the mean (approximately 93rd percentile), commonly used as a clinical threshold suggesting significant symptoms.

Stimulation of Trace Amine-Associated Receptor 1, a receptor involved in regulating dopamine and serotonin signaling. Some emerging ADHD medications target TAAR1, which modulates neurotransmitter release through a different mechanism than traditional stimulants.

Rapid decrease in drug response after repeated doses within a short period.

Medication delivery systems designed to prevent misuse by making pills difficult to crush, dissolve, or extract for non-oral administration. Examples include prodrug technology (lisdexamfetamine) and extended-release matrices that cannot easily be defeated.

The gradual reduction of a medication dose over days or weeks rather than abrupt discontinuation. Tapering reduces the risk of withdrawal symptoms or rebound effects, particularly with alpha-2 agonists such as clonidine and guanfacine.

A research methodology that uses observational (real-world) data to mimic what a randomized controlled trial would have found. Applies randomized trial design principles to existing data to reduce bias and strengthen causal conclusions.

A set of brain regions that activate during focused, goal-directed tasks. In healthy brains, the Task-Positive Network and Default Mode Network alternate — one activates while the other deactivates. In ADHD, this alternation is impaired.

Treatment As Usual — a control condition in clinical trials where participants receive standard community care rather than the experimental intervention. Used as the comparator in many ADHD psychosocial treatment studies to establish whether structured interventions outperform routine clinical practice.

Tricyclic Antidepressant — an older class of antidepressants (e.g., nortriptyline, imipramine, desipramine) sometimes used off-label for ADHD. Moderate efficacy (SMD ~0.3–0.5) but carries significant cardiac risk, including QTc prolongation and risk of fatal arrhythmia in overdose. Generally reserved as a late-line option.

A substance that causes birth defects when exposure occurs during pregnancy.

A measure of how consistently a test produces the same results when administered to the same person at different times. High test-retest reliability indicates stable measurement, which is essential for tracking symptom changes over time.

Trauma-Focused Cognitive Behavioral Therapy — a structured, evidence-based treatment for children and adolescents experiencing trauma-related emotional and behavioral difficulties. Recommended first-line for pediatric PTSD.

A guideline for multi-informant ADHD assessment stating that a symptom counts as present if endorsed by any single informant (parent OR teacher), rather than requiring agreement from both. This approach increases diagnostic sensitivity because ADHD symptoms often vary by setting.

Quality of the working relationship between clinician and patient, characterized by agreed-upon treatment goals, collaboration on interventions, and mutual emotional connection. Strong alliance independently predicts better treatment outcomes across psychotherapy and pharmacotherapy.

The determination that two pharmaceutical products (typically brand-name and generic) will produce the same clinical effect and safety profile when administered to patients under the same conditions. Not all generics meet this standard equally.

The margin between an effective dose and a toxic dose. A narrow therapeutic index means a dangerously small margin.

The dose range between minimum effective concentration and toxic concentration.

Treatment approach pursued after first-line and second-line agents or therapies have been adequately trialed without remission. Often includes higher-dose augmentation, combination pharmacotherapy, or novel agents like ketamine or psychedelic-assisted therapies.

A neurological deficit in temporal processing. Not willful disregard for time, but genuine difficulty perceiving time intervals.

The process of gradually adjusting a medication dose to find the optimal balance between efficacy and side effects.

Time to maximum concentration — the time after taking a medication when it reaches its highest level in the blood. Determines how quickly a medication begins working. Relevant to timing ADHD medication relative to school or work demands.

A reinforcement system where individuals earn tokens for desired behaviors that can be exchanged for rewards.

Baseline, sustained dopamine levels that set overall arousal and readiness for action.

Two patterns of irritability with different clinical implications. Tonic (chronic, baseline) irritability is persistently elevated and associated with depression and anxiety. Phasic (episodic) irritability occurs in discrete episodes and is more associated with bipolar disorder or ODD.

A neurodevelopmental disorder characterized by multiple motor tics and at least one vocal tic persisting for more than one year.

Test of Variables of Attention. A continuous performance test measuring attention and impulse control.

Task-Positive Network — a set of brain regions (dorsolateral prefrontal cortex, posterior parietal cortex, supplementary motor area) that activate during goal-directed tasks requiring focused attention. In ADHD, the normal anticorrelation between the TPN and Default Mode Network is disrupted, leading to DMN intrusion during tasks.

The planned transfer of clinical responsibility from pediatric to adult healthcare providers.

An event or series of events that is physically or emotionally harmful and has lasting adverse effects on functioning.

Structured, evidence-based decision pathway guiding sequential treatment choices based on patient response at each step. Typically organized as first-line, second-line, and treatment-resistant options with defined criteria for advancing.

The degree to which an intervention is delivered as intended in its original design.

A finding in long-term ADHD studies where the outcomes of treated and untreated groups become more similar over years. May reflect treatment discontinuation, development of coping skills, or natural symptom reduction — and complicates interpretation of long-term medication benefits.

A clinically significant reduction in symptoms following an intervention.

Failure to achieve remission despite adequate trials (adequate dose, adequate duration per Domschke staging criteria) of at least two first-line or second-line psychopharmacological agents. Triggers evaluation for third-line strategies and reassessment of diagnosis.

Positive Parenting Program — a multi-level, evidence-based parenting and family support system with five levels of increasing intensity. Designed to prevent and treat behavioral and emotional problems in children.

A medication that blocks the reuptake of three neurotransmitters — dopamine, norepinephrine, and serotonin — simultaneously. An emerging pharmacological approach for ADHD that may address a broader range of symptoms than current medications.

A student who is both gifted and has a disability.

The co-occurrence of giftedness and a disability (such as ADHD) in the same individual. Twice-exceptional (2e) students are often underidentified because giftedness masks ADHD deficits and ADHD masks gifted abilities.

A widely used clinician-administered or self-report measure for assessing trauma exposure and PTSD symptoms in children and adolescents, aligned with DSM-5 criteria.

A white matter tract connecting emotion centers (amygdala, limbic structures) to self-regulation centers (prefrontal cortex). When degraded, the prefrontal cortex has reduced ability to modulate emotional reactions.

Vanderbilt ADHD Diagnostic Rating Scale. A free, validated rating scale for attention disorder diagnosis and monitoring.

An anticonvulsant and mood stabilizer (Depakote) used for bipolar disorder and seizure prevention. Requires monitoring for liver function and blood counts.

A free, publicly available ADHD rating scale system with parent and teacher forms. Screens for core ADHD symptoms and common comorbidities (ODD, conduct disorder, anxiety, depression). Widely used in primary care.

An SNRI antidepressant (Effexor) used for depression, anxiety, and chronic pain. At lower doses acts primarily on serotonin; at higher doses adds significant norepinephrine reuptake inhibition.

A non-stimulant medication (Qelbree) approved for attention disorders. Functions primarily as a norepinephrine reuptake inhibitor with additional serotonin modulating activity. Onset in 1–2 weeks.

Vesicular Monoamine Transporter — a protein that packages monoamine neurotransmitters (dopamine, norepinephrine, serotonin) into synaptic vesicles for release. VMAT2 is the primary brain isoform. Amphetamines interact with VMAT2 to promote reverse transport of dopamine from vesicles into the cytoplasm, contributing to their mechanism of action beyond simple reuptake inhibition.

Vesicular Monoamine Transporter 2. The protein that packages dopamine and norepinephrine into storage vesicles inside neurons.

Brand name for lisdexamfetamine, a prodrug that requires enzymatic cleavage in the bloodstream to release active d-amphetamine. Lower abuse potential due to prodrug mechanism.

Time required after discontinuing one medication before starting another, allowing the first drug to clear sufficiently to avoid interactions. Critical when switching between MAOIs and serotonergic agents (typically 14 days for MAOIs, 5 half-lives for the prior agent).

Brand name for bupropion, a norepinephrine-dopamine reuptake inhibitor used off-label for ADHD. Also FDA-approved for depression and smoking cessation.

A retrospective self-report questionnaire that asks adults to recall their childhood ADHD symptoms. Used as part of the diagnostic process for adult ADHD, though retrospective self-report has known accuracy limitations.

Weiss Functional Impairment Rating Scale — a comprehensive measure of functional impairment across family, work/school, social, life skills, self-concept, and risk-taking domains. Used to document the functional impact required by DSM-5-TR for ADHD diagnosis and to track treatment response beyond symptom counts.

The wiring that connects brain areas to each other. Disruptions in white matter integrity are associated with various psychiatric conditions.

The cognitive system that temporarily holds and manipulates information needed for complex tasks like reasoning, comprehension, and learning. A core executive function impaired in many individuals with ADHD. Depends on prefrontal cortex networks modulated by dopamine (D1 receptors) and norepinephrine (α2A receptors).

A change in a child's position on growth charts expressed in standard deviations. A downward Z-score shift in height indicates that a child is growing more slowly than expected, used to track potential growth suppression from stimulant medications.

A colloquial term describing emotional flattening, reduced spontaneity, and personality dampening that some children experience on stimulant medication — appearing overly subdued or 'zombie-like.' Usually indicates the dose is too high or the medication is not a good fit.