What is Attention Deficit Hyperactivity Disorder (ADHD)?

What is ADHD?

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by persistent symptoms of inattention, hyperactivity, and impulsivity that cause significant impairment across multiple settings and are not better explained by another mental disorder. 1

Core Characteristics and Diagnostic Criteria

ADHD presents with two primary symptom domains:

Inattentive Symptoms

• Poor attention to detail/careless mistakes
• Difficulty concentrating or sustaining attention on tasks
• Seeming preoccupied, difficulty shifting focus even when spoken to directly
• Difficulty completing tasks (gets distracted/sidetracked)
• Organizational challenges (chronic lateness, messiness, disorganized work)
• Reluctance to engage in tasks requiring sustained mental effort
• Difficulty keeping track of belongings
• Easily distracted
• Frequently forgetful 1, 2

Hyperactive-Impulsive Symptoms

• Frequent fidgeting
• Difficulty sitting still for prolonged periods
• Inner restlessness or agitation
• Disruptive behavior
• Always "on the go"
• Excessive talking
• Interrupting others
• High impatience
• Intrusive behavior 1

For diagnosis, symptoms must:

• Be present before age 12
• Persist for at least 6 months
• Occur in 2 or more settings (e.g., home, school/work)
• Cause significant impairment in functioning
• Not be better explained by another mental disorder 2

Types of ADHD

ADHD is classified into three presentations:

1. Predominantly Inattentive Type: 5+ inattentive symptoms, <5 hyperactive-impulsive symptoms
2. Predominantly Hyperactive-Impulsive Type: 5+ hyperactive-impulsive symptoms, <5 inattentive symptoms
3. Combined Type: 5+ symptoms in both categories 1

Epidemiology and Course

• ADHD affects approximately 8% of children and youth 1
• 14.6% of U.S. adults meet DSM-5 criteria for ADHD 3
• ADHD diagnosed in childhood often persists into adulthood 3
• Adults with ADHD are more likely to present with inattentive symptoms 1
• ADHD is a chronic condition requiring ongoing management 1

Etiology

The specific etiology of ADHD is unknown, but evidence suggests:

• Neurobiological basis involving norepinephrine and dopamine dysregulation in brain areas responsible for attention and behavior regulation 4
• Genetic factors contribute to heritability, though no single genetic marker has been consistently identified 5
• Environmental factors may play a role in symptom expression and severity

Common Comorbidities

ADHD frequently co-occurs with:

• Emotional/behavioral disorders (anxiety, depression, oppositional defiant disorder, conduct disorder)
• Developmental conditions (learning disorders, language disorders)
• Physical conditions (tics, sleep disorders)
• Substance use disorders (especially in untreated adolescents and adults) 1, 3

Comorbidity rates range from 12-60%, with significant symptom overlap that can complicate diagnosis 5.

Assessment and Diagnosis

Diagnosis requires:

• Comprehensive clinical history and evaluation
• Assessment using validated rating scales (e.g., Adult ADHD Self-Report Scale, Conners' Adult ADHD Rating Scales)
• Collection of information from multiple sources (parents, teachers, self-report)
• Ruling out alternative explanations for symptoms 3

Treatment Approaches

Treatment is multimodal and should be tailored to the individual:

Pharmacological Treatment

• First-line medications: Stimulants (methylphenidate and amphetamine derivatives) 6, 7
• Non-stimulant options: Atomoxetine, viloxazine, bupropion (especially for those with comorbid anxiety/depression) 6, 2
• Medications should be carefully monitored for cardiovascular effects, though serious adverse events are rare 7

Non-pharmacological Approaches

• Evidence-based parent training and behavioral management (first-line for children 4-6 years) 6
• Cognitive-behavioral therapy focused on organization skills, time management, and emotional regulation 6
• Educational interventions and accommodations 6
• Psychosocial interventions 1

Regional Differences in Treatment Approaches

Treatment guidelines vary globally:

• Western guidelines often recommend FDA-approved medications along with behavioral interventions 1
• Japanese guidelines recommend school environment management and psychosocial treatment as first-line, with medications as second-line 1
• Treatment approaches should consider cultural and regional contexts 1

Pitfalls in Diagnosis and Management

• Misattribution of symptoms to other conditions (especially in adults)
• Inadequate assessment of comorbidities
• Insufficient dosing of medications
• Lack of multimodal treatment approach
• Failure to monitor treatment response and adjust accordingly 6

ADHD is a complex neurodevelopmental disorder requiring comprehensive assessment and individualized treatment to address symptoms and improve quality of life across multiple domains.