Attention-deficit/hyperactivity disorder (ADHD) is an early-onset clinically heterogeneous disorder of inattention, hyperactivity, and impulsivity. The nosology has changed during the past century from minimal brain damage to hyperkinetic reaction of childhood and now to ADHD. These names reflect shifting causative theories, from an early emphasis on subtle "minimal" brain injuries to motor hyperactivity and eventually to the primacy of cognitive and attentional symptoms. Indeed, neuropsychological deficits reported in patients with ADHD implicate executive dysfunctions and working memory deficits that are similar to those in patients with acquired frontal lobe damage. In addition, neuroimaging studies1 implicate frontal-subcortical pathways in patients with ADHD. While there is undoubtedly a complex interplay between genetic and environmental interactions, estimates of heritability from twin studies are high (approximately 80%).1 Moreover, recently there has been a growing appreciation of the magnitude of impairment experienced by adults with continuing ADHD after childhood onset.
Spencer TJ. Attention-Deficit/Hyperactivity Disorder. Arch Neurol. 2002;59(2):314-316. doi:10.1001/archneur.59.2.314