Attention-Deficit/Hyperactivity Disorder

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DESCRIPTION

  • Attention-deficit/hyperactivity disorder (ADHD) is a chronic neurodevelopmental condition characterized by a persistent pattern of inattentive and/or hyperactive/impulsive behaviors that negatively impact academic performance, social-emotional development, and/or daily function.
  • Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) criteria for diagnosis list 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)
    • Symptoms are developmentally inappropriate and several existed before the age of 12 years.
    • Behaviors persist for ≥6 months and observed in two or more settings (e.g., home, school, recreational settings, afterschool programs, and family/community-based activities). Behaviors interfere with, or reduce the quality of, school performance, social interactions, and/or occupational functioning.
  • Classified into three types/presentations of predominant behavior:
    • Hyperactive/impulsive
    • Inattentive
    • Combined type (most frequently comes to clinical attention)
  • May classify as mild, moderate, or severe based on behavior severity
  • Behaviors cannot be better explained by another mental health disorder. Autism spectrum disorder is no longer an exclusion criterion.

EPIDEMIOLOGY

  • More common in males than in females
  • Median age of onset is 6 years (severe cases diagnosed at median age of 4 years). Approximately, 1/3 of cases retain diagnosis as adults.
  • 9–15% prevalence of school-aged children

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.
  • Heritability risk of ~75% based on 1st-degree relative and twin study data; genetic variants (single nucleotide polymorphisms, copy number variants) identified, although not ADHD-specific

COMMONLY ASSOCIATED CONDITIONS

  • Learning disorders (20–60%)
  • Anxiety disorder (20–40%)
  • Depression (~30%)
  • Oppositional defiant disorder (50–80%) and conduct disorder (~30%)
  • Developmental coordination disorder (~50%)
  • Tic disorder (may affect treatment decisions)
  • Sleep disorders

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