Impact of comorbidity in adults with attention-deficit/hyperactivity disorder.

Persistence of attention-deficit/hyperactivity disorder (ADHD) into adulthood and male-to-female ratios of this disorder in childhood and adulthood have been controversial issues in the ADHD diagnosis in adults. Research has resolved these controversies and in turn provided support for the validity of the diagnosis in adults. Support for the diagnosis can also be found in data that show the lifetime prevalence rate for comorbid conditions such as antisocial disorders, mood and anxiety disorders, and substance abuse disorders to be consistent across pediatric and adult populations with ADHD. These coexisting conditions add not only to the impairment associated with ADHD in adults but also to the disorder's economic burden, the extent of which is currently unknown. However, adults with the disorder, like children, probably have higher health care use and costs than people without the disorder. Little, too, is known about the social cost of ADHD, but if left untreated, the impact may be substantial. Research to determine the occupational costs associated with ADHD is ongoing, but until that and other cost-of-illness data are available, studies on the economic costs of the comorbid conditions depression, anxiety, and substance abuse and dependence may be used to make suppositions about the economic impact of ADHD in adults. More studies are needed on the outcomes of adults with this disorder, especially cost-of-illness studies.