Clinical and Diagnostic Implications of Lifetime Attention-Deficit/Hyperactivity Disorder Comorbidity in Adults with Bipolar Disorder: Data from the First 1000 STEP-BD Participants

Background Systematic studies of children and adolescents with a diagnosis of bipolar disorder show that rates of attention-deficit/hyperactivity disorder (ADHD) range from 60% to 90%, but the prevalence and implications of ADHD in adults with bipolar disorder are less clear. Methods The first consecutive 1000 adults with bipolar disorder enrolled in the National Institute of Mental Health’s Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) were assessed for lifetime ADHD. The retrospective course of bipolar disorder, current mood state, and prevalence of other comorbid psychiatric diagnoses were compared for the groups with and without lifetime comorbid ADHD. Results The overall lifetime prevalence of comorbid ADHD in this large cohort of bipolar patients was 9.5% (95% confidence interval 7.6%–11.4%); 14.7% of male patients and 5.8% of female patients with bipolar disorder had lifetime ADHD. Patients with bipolar disorder and ADHD had the onset of their mood disorder approximately 5 years earlier. After adjusting for age of onset, those with ADHD comorbidity had shorter periods of wellness and were more frequently depressed. We found that patients with bipolar disorder comorbid with ADHD had a greater number of other comorbid psychiatric diagnoses compared with those without comorbid ADHD, with substantially higher rates of several anxiety disorders and alcohol and substance abuse and dependence. Conclusions Lifetime ADHD is a frequent comorbid condition in adults with bipolar disorder, associated with a worse course of bipolar disorder and greater burden of other psychiatric comorbid conditions. Studies are needed that focus on the efficacy and safety of treating ADHD comorbid with bipolar disorder.