Attention Deficit Hyperactivity Disorder

Attention Deficit Hyperactivity Disorder (ADHD) is a complex, heterogeneous condition defined by persistent, age-inappropriate levels of inattention, hyperactivity, and impulsivity that significantly impair daily functioning. While often perceived as a modern phenomenon linked to digital technology, ADHD-like symptoms have been documented for over a century. The disorder is now recognized not just as a childhood condition, but as one that frequently persists into adolescence and adulthood, with some individuals exhibiting a late-onset variant.

Global prevalence estimates for children hover around 7.2%, though reported rates vary widely due to differences in diagnostic criteria, clinical referral patterns, and the informants used. Boys are diagnosed two to three times more frequently than girls, though this gap narrows in adulthood, suggesting that girls may be underdiagnosed due to less disruptive symptom presentations. Beyond core symptoms, ADHD is highly comorbid with conditions such as oppositional defiant disorder, anxiety, mood disorders, and learning disabilities. The functional impact is profound, spanning academic underachievement, social rejection, occupational instability, and increased risks for substance abuse and accidental injury.

Diagnosis relies on standardized criteria from the DSM or ICD, which require symptoms to be pervasive across settings and cause significant impairment. However, these criteria are often applied inconsistently in practice. Standard treatment involves a combination of behavioral therapy and medication (stimulants or nonstimulants). While these are effective for many, they do not provide complete relief for all patients, and there is a lack of robust evidence for the long-term efficacy of medication beyond two years. Alternative treatments like dietary changes or neurofeedback remain popular but currently lack the rigorous scientific backing required for clinical recommendation.

ADHD is a multifactorial disorder with high heritability (approximately 74%), yet no single gene or environmental factor is sufficient to cause it. Research points to a complex interplay between genetic risk and environmental factors like prenatal complications. Neurobiologically, ADHD is associated with structural and functional abnormalities in the frontostriatal circuit, often interpreted as a developmental delay in brain maturation rather than a static deficit. Current research is shifting from a categorical approach to a spectrum-based view, aiming to better capture the disorder's heterogeneity.