Addressing Comorbidity in Adults With Attention-Deficit/Hyperactivity Disorder

Psychiatric comorbidity complicates the accurate diagnosis and effective treatment of attentiondeficit/hyperactivity disorder (ADHD) in adults. This paper examines the influence of comorbidity ontreatment responsiveness in ADHD adults, the neurobiological underpinnings of comorbidity, and thepotential of different pharmacologic agents to address comorbid states in ADHD. A categoricalschema for neurobiological classification of ADHD subtypes is integrated with literature associatingspecific neurotransmitters with corresponding neurobehavioral abnormalities. Dopamine, for example,is one of several neurotransmitters implicated in bipolar disorder. Serotonin and norepinephrineare implicated in major depression and anxiety disorders, while self-medication for dopaminedysfunction may relate to substance abuse. Norepinephrine and serotonin have each been linked toaggression and impulsive antisocial behaviors. The effective treatment of ADHD with comorbid psychiatricdisorders requires knowledge of the neurochemical underpinnings of each disorder and expertisein the application of appropriate pharmacologic tools. Controlled studies assessing treatment outcomesfor both comorbid disorders will assist in the development of improved treatment strategies foradults with complicated ADHD.