Bipolar Symptoms in Adult Attention-Deficit/Hyperactivity Disorder: A Cross-Sectional Study of 510 Clinically Diagnosed Patients and 417 Population-Based Controls

Objective: Bipolar spectrum disorders (BSD) have several symptoms and features in common with attention-deficit/hyperactivity disorder (ADHD). Here we explored the prevalence of BSD and the relationship between symptoms of BSD and ADHD in adult ADHD patients. Method: Norwegian adults diagnosed with DSM-IV ADHD during 1997 through 2007 (n = 510) and a random sample of 417 controls from the general population (aged 18-40 years) were recruited and responded to 85 questions rating symptoms of ADHD, lifetime symptoms of mood disorders, other comorbid conditions, and sociodemographic data. Results: According to the Mood Disorder Questionnaire (MDQ), 50.6% of the ADHD patients screened positive for BSD, compared to of the controls. In comparison, the prevalence of BSD according to DSM-IV in a subsample of viewed patients (n = 50) was 32%. In the whole study sample (N = 927), an ADHD diagnosis was the strongest predictor for screening positive on the MDQ (OR = 5.0, P <,001), but the correlation between dimensional symptom levels of ADHD and of BSD was strongest in the control group (Pearson correlation r = 0.7, P <.001 vs r = 0.3, P <.00 I). Patients screening positive on the MDQ had significantly more drug problems, higher ADHD symptom scores, and lower educational and occupational levels. Conclusions: Our findings illustrate the close relationship between some symptoms of BSD and ADHD in adults. In clinical and research settings, patients screening positive for BSD should be assessed for a possible underlying or coexisting ADHD condition and vice versa. J Clin Psychiatry 2010;71(1):48-57 (C) Copyright 2010 Physicians Postgraduate Press, Inc.