Description

• Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that manifests in early childhood characterized by distractibility, impulsivity, hyperactivity, and/or inattention.
• Three subsets: predominantly hyperactivity (ADHD-H), predominantly inattentive (ADHD-I), or combined (ADHD-C)
• System(s) affected: nervous

Epidemiology

• Predominant age: onset <12 years; lasts into adolescence and adulthood
• Predominant sex: assigned male at birth > assigned female at birth (2:1); ADHD-I is more common in patients assigned female at birth.

Prevalence
9–15% of children aged 4 to 17 years

Etiology and Pathophysiology

Not definitive—suggested pathogenesis includes imbalance of catecholamine metabolism and structural brain differences. Environmental influences are controversial.

Risk Factors

• Family history (genetic component)
• Medical causes (affecting brain development)—including prenatal tobacco exposure and prematurity

Commonly Associated Conditions

• Mood disorders—depression, anxiety
• Behavior disorders—oppositional defiant disorder, conduct disorder
• Autism spectrum disorder
• Physiologic disorders—sleep disorders, tics
• Learning disabilities, developmental coordination syndrome, language disorder
• Substance use disorders