Attention-Deficit/Hyperactivity Disorder



  • Attention-deficit/hyperactivity disorder (ADHD) is a chronic condition that is characterized by a persistent pattern of developmentally inappropriate inattention and/or hyperactivity/impulsivity interfering with function or development.
  • DSM-5 criteria for diagnosis lists 18 core symptoms:
    • At least 6 of 9 symptoms of inattention and/or 6 of 9 hyperactivity/impulsivity symptoms (5 of 9 in individuals >17 years of age)
    • These maladaptive symptoms have been persisting for at least 6 months.
    • Clear impairment, interference, or reduction in quality of academic, social, occupational function
    • Several symptoms existed before age 12 years, several symptoms present in two or more settings (e.g., home, school, day care, after-school activities, church, and community activities).
  • Classified into three subtypes:
    • Hyperactive/impulsive
    • Inattentive
    • Combined type (most frequently comes to clinical attention)
  • Symptoms not solely due to opposition and cannot be better explained by another mental health disorder. Autism spectrum disorder is no longer an exclusion criterion.


  • 2:1 male-to-female ratio
  • 3–10% prevalence of school-age children
  • Females more likely to have inattentive type

Risk Factors

Studies using MRI and other imaging demonstrate differences in brain anatomy, function and connectivity between executive functioning networks and reward networks, implicating dopamine and noradrenergic transmission in ADHD.


  • Risk of ADHD in 1st-degree relatives is ~25%.
  • Concordance in monozygotic twins: 59–81%; dizygotic twins: 33%

Commonly Associated Conditions

  • Learning disorders
  • Language disorders
  • Anxiety and mood disorders
  • Sleep disorders
  • Tic disorder (may affect treatment decisions)
  • Oppositional defiant disorder and conduct disorder
  • Poor social skills

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