Adult attention-deficit/hyperactivity disorder (ADHD) is increasingly recognized and reported to frequently coexist with bipolar disorder. Concurrent diagnosis of adult ADHD and bipolar disorder remains controversial. In this study, we conducted a systematic review to examine the rates and diagnostic validity of the concept of comorbid adult ADHD and bipolar disorder.
MEDLINE, Embase, PsycInfo, and Cochrane databases were searched for articles published before March 30, 2007, using the keywords manic, bipolar, attention deficit hyperactivity, and adult. The computer search was supplemented with bibliographic cross-referencing.
Exclusion criteria were studies with only pediatric subjects, childhood ADHD only but not adult ADHD, and either bipolar disorder or ADHD only, but not both; review articles, case reports; letters to the editor; and book chapters. Of the 262 citations found, 12 studies met our inclusion criteria.
Specific diagnostic validating criteria examined were phenomenology, course of illness, heredity, biological markers, and treatment response. There were 6 studies on comorbid rates, 4 on phenomenology, 3 on course of illness, 2 on heredity, none on biological markers, and 1 on treatment response.
The proposed comorbid syndrome is fairly common (present in up to 47% of adult ADHD and 21% of bipolar disorder populations), with a more severe course of illness compared with that of bipolar disorder alone, and high rates of comorbidity with other psychiatric disorders. Its treatment appears to require initial mood stabilization.
Comorbid adult ADHD and bipolar disorder has been insufficiently studied, with more emphasis on comorbidity rates and few data on course, neurobiology, heredity, and treatment. The diagnostic validity of adult ADHD/ bipolar disorder as a true comorbidity is not well-established on the basis of this equivocal and insufficient literature. More studies are greatly needed to further clarify its diagnostic validity and treatment approach.