The prevalence of bipolar spectrum disorder in elderly patients with recurrent depression

PURPOSE Despite a growing body of knowledge on bipolar spectrum disorder (BSD), relatively little is known about the clinical characteristics of BSD in elderly people. We investigated the prevalence of BSD in elderly patients with recurrent depression. PATIENTS AND METHODS A total of 65 elderly outpatients (≥60 years of age) who met the Diagnostic and Statistical Manual of Mental Disorders IV criteria for recurrent major depressive disorder participated in the study. BSD was diagnosed according to the criteria developed by Ghaemi et al and the Mood Disorder Questionnaire (MDQ) was used to assess bipolarity. RESULTS Of 65 subjects, eleven (16.9%) and 54 (83.1%) were diagnosed with BSD and unipolar depression, respectively. A total of 32.3% (n=22) had a positive screen for bipolar disorder, and we found a significant association between the BSD criteria and the criteria for a positive MDQ (P<0.001). Patients with BSD had a longer duration of illness (P=0.040) and more prior depressive episodes (P<0.001) than did those with unipolar depression. The BSD criteria of first-degree relative with bipolar disorder (P=0.030), antidepressant-induced hypomania (P=0.034), hyperthymic personality (P=0.001), and atypical depression (P=0.030) were highly associated with MDQ-positive patients. CONCLUSION Our results indicate that many depressed elderly patients have bipolar-related illness; moreover, some features of the depression are associated with bipolarity.