ADHD: Full Clinical Summary

1. Definition & Overview

2. Epidemiology

• The Harriet Lane Handbook, 23rd ed.; Kaplan & Sadock

3. DSM-5 Diagnostic Criteria

1. Symptoms: Inattention and/or hyperactivity-impulsivity that are more frequent and severe than expected for developmental age
2. Duration: Symptoms persist for ≥6 months
3. Onset: Symptoms present before age 12
4. Pervasiveness: Evidence in two or more settings (e.g., home and school)
5. Impairment: Clear interference with functioning or development

Subtypes (DSM-5)

• Combined presentation - both inattention and hyperactivity-impulsivity
• Predominantly inattentive presentation
• Predominantly hyperactive-impulsive presentation

Note: ICD-11 supports first-time diagnosis in adults, provided symptoms were present in childhood. - Maudsley Prescribing Guidelines, 15th ed.

4. Pathophysiology & Neurobiology

• Prefrontal cortex (PFC): Governs executive functions (inhibition, planning, attention, organization, problem-solving, motor control)
• Dopamine system: Projections from the ventral tegmental area (VTA) to the PFC and nucleus accumbens are hypoactive
• Norepinephrine system: Locus coeruleus projections to the cortex and thalamus are dysregulated
• Basal ganglia / striatum: Involved in motor control and reward processing; structurally and functionally altered in ADHD
• Anterior cingulate cortex: Impaired error-monitoring and sustained attention

5. Clinical Features

Inattention symptoms (≥6 for children; ≥5 for adults ≥17 years)

• Fails to give close attention to details / makes careless mistakes
• Difficulty sustaining attention in tasks or play
• Does not seem to listen when spoken to directly
• Does not follow through on instructions; fails to finish tasks
• Difficulty organizing tasks and activities
• Avoids tasks requiring sustained mental effort
• Often loses things necessary for tasks
• Easily distracted by extraneous stimuli
• Often forgetful in daily activities

Hyperactivity-Impulsivity symptoms (≥6 for children; ≥5 for adults ≥17 years)

• Fidgets, taps hands/feet, squirms
• Leaves seat when expected to remain seated
• Runs or climbs excessively (in adults: subjective restlessness)
• Unable to play/engage in activities quietly
• "On the go" as if driven by a motor
• Talks excessively
• Blurts out answers before questions completed
• Difficulty awaiting turn
• Interrupts or intrudes on others

6. Evaluation & Diagnosis

• Rating scales: Vanderbilt Diagnostic Rating Scales (parent and teacher versions) are recommended for children with academic/behavioral concerns. Also used to monitor treatment response. - Harriet Lane Handbook
• Adult diagnostic interview: DIVA-5 (Diagnostic Interview for ADHD in Adults, based on DSM-5 criteria) is the recommended validated tool for adults. - Maudsley
• Lab/imaging: Not routinely required if medical history is unremarkable. Neuropsychological testing is not required for diagnosis but is useful if academic/developmental concerns are also present.
• Before starting stimulants: Exclude cardiac symptoms, Wolff-Parkinson-White syndrome, family history of sudden death, hypertrophic cardiomyopathy, and long QT syndrome. Cardiology referral if cardiac history exists. Routine ECG is not required without personal/family cardiac history.

Differential Diagnosis

7. Management

Step 1: Non-Pharmacological (always adjunct; first-line in preschoolers)

• Behavioral therapy: Best combined with pharmacotherapy in school-age children
• Preschoolers (age 4-5): Behavioral therapy alone should be tried first before medications
• Cognitive Behavioral Therapy (CBT): Especially useful in adults; can be used when there is partial medication response or intolerance
• Environmental modifications: Structured routines, classroom accommodations, parent training

Step 2: Pharmacotherapy

First-Line - Stimulants (65-75% response rate)

• Mechanism: Blocks DA and NE reuptake transporters
• Forms: Immediate release (IR) - BID/TID; Extended release (ER) preferred for adherence and coverage
• Adequate trial dose: >0.8 mg/kg/day
• Key formulations: Concerta (IR 22%/ER 78%), Aptensio XR, Cotempla XR-ODT, Azstarys (prodrug)

• Mechanism: Block reuptake AND promote DA/NE release (more potent)
• Adequate trial dose: ≥0.5 mg/kg/day for mixed amphetamine salts
• Key formulations: Adderall XR, Vyvanse (lisdexamfetamine - prodrug, lower abuse potential)

Second-Line - Non-Stimulants

Atomoxetine is preferred when stimulants are not tolerated, are contraindicated, or two separate 6-week trials fail. - Maudsley Prescribing Guidelines

Common Stimulant Side Effects

• Appetite suppression (most common)
• Abdominal pain / nausea
• Headache
• Sleep disturbance (especially insomnia)
• Palpitations / elevated HR and BP
• Growth deceleration (with long-term use in children)

8. Monitoring

• Weight, blood pressure, heart rate: All ADHD medications
• Liver function + suicidal ideation: Atomoxetine specifically
• Annual medication review: Required - reassess whether medication should be continued
• Cardiovascular surveillance: A 2024 population study found a dose-related increase in cardiovascular disease risk with stimulants (earlier 2022 meta-analysis found no adverse CV effect) - monitor cardiovascular signs and symptoms throughout treatment. - Maudsley, 15th ed.
• "Drug holidays": Consider ad hoc periods of stopping or dose reduction to minimize adverse outcomes and re-evaluate need

9. Special Populations

Children (age 4-5 years)

• Behavioral therapy is first-line; medications only if behavioral therapy fails or is unavailable
• Stimulant titration is weight-based

Adolescents

• Most affected children continue to meet diagnostic criteria through adolescence
• Extended-release formulations preferred to reduce abuse/diversion

Adults

• ADHD is under-recognized in adults; rates rising globally
• DIVA-5 recommended for assessment
• Modified-release (MR) preparations or non-stimulants preferred to reduce diversion risk
• Comorbid bipolar disorder or psychosis: ADHD medications may worsen these; exercise caution
• Evidence for long-term treatment benefit in adults is currently rated "low" or "very low" in quality - short-term trials show symptom improvement but limited quality-of-life data beyond 52 weeks

Pregnancy

• Separate ADHD-in-pregnancy guidelines exist (Maudsley block 5, line 2310); stimulants carry fetal risk and should be carefully reviewed

10. Comorbidities

• Oppositional Defiant Disorder (ODD)
• Conduct Disorder (CD)
• Anxiety disorders
• Depression / mood disorders
• Learning disabilities
• Tic disorders / Tourette syndrome
• Substance use disorders (untreated ADHD is a risk factor)

Key Sources

• Kaplan & Sadock's Comprehensive Textbook of Psychiatry - pharmacotherapy & neurobiology
• The Harriet Lane Handbook, 23rd ed. (Johns Hopkins) - pediatric diagnosis & management
• Maudsley Prescribing Guidelines in Psychiatry, 15th ed. - adult treatment, monitoring, NICE guidance