Abstract
BACKGROUND: Given the general population prevalence rates of obsessive compulsive disorder (OCD) and the affective disorders, one would expect the co-occurrence of these syndromes to be rare. Yet findings by our group and others have revealed extremely high rates of comorbidity in OCD with both depressive disorders (DD; 50%) and bipolar disorder (BPD; 10%). The current investigation sought to further clarify the role affective disorder comorbidity-particularly that with BPD-may play in the clinical expression of OCD. METHOD: A total of 605 individuals with OCD were evaluated with the Structured Clinical Interview for DSM-IV. The sample included three groups: BPD (bipolar I or II; N = 79, 13.1%), DD (major depression or dysthymia; N = 388, 64.1%), and NAD (no affective disorder comorbidity; N = 138, 22.8%). Group-wise comparisons were conducted on comorbidity patterns, impairment measures, and clinical features of OCD. RESULTS: Analyses revealed a graded severity pattern, with the BPD group as the most severe, followed by the DD group, and finally the NAD group. Severity was reflected by the total number of Axis I disorders (P<.01), the number of psychiatric hospitalizations (P<.001), impairment measures (Ps<.05), and OCD symptoms (P<.01). It is worth noting that the impairment and OCD symptom severity findings were not attributable to the higher level of nonmood disorder comorbidities in the BPD and DD groups. RESULTS: Those individuals with comorbid affective disorders, particularly BPD, represent a clinically severe group compared to those without such comorbidity. Clarifying the phenomenological features of OCD-affective disorder comorbidity has important etiological and treatment implications.