Obsessive-compulsive symptoms in major depressive disorder correlate with clinical severity and mixed features.

Obsessive-compulsive symptoms (OCS) are often reported in patients with bipolar disorder. The aim of this study was to investigate OCS and their related clinical features in major depressive disorder (MDD). The analysis involved 482 outpatients with MDD collected within the Combining Medications to Enhance Depression outcomes trial, who were assessed with scales for depression, suicidality, irritability, hypomanic symptomatology, and other comorbid psychiatric manifestations. OCS were reported in 27% of the sample. Patients with MDD experiencing OCS were found to differ from those not experiencing OCS by a greater severity of depression (d = 0.41, P = 0.0001), more hypomanic symptoms (d = 0.48, P < 0.0001) and mixed features (22% vs. 10%, P = 0.001), increased levels of suicidal thoughts (d = 0.40, P = 0.0001), a lower likelihood of achieving remission after antidepressant treatment (19% vs. 33%, P = 0.0109), as well as more comorbid anxiety disorders (i.e. panic disorder: d = 0.98, P < 0.0001; generalized anxiety disorder: d = 0.74, P < 0.0001; social phobia: d = 0.71, P < 0.0001), and post-traumatic stress disorder (d = 0.81, P < 0.0001). In light of these findings, clinicians should pay more attention to the occurrence of OCS in MDD, as these symptoms may reflect greater clinical severity, poorer treatment outcome, and increased risk for bipolarity.