Role of substance abuse comorbidity and personality on the outcome of depression in bipolar disorder: harm avoidance influences medium-term treatment outcome

Comorbid conditions are frequent in bipolar disorder (BD) and may complicate the treatment and course of illness. We investigated the role of substance use disorder (SUD), axis II personality disorders (PD) and continuous personality traits on the medium-term outcome (6 months) of treatment for bipolar depression. One hundred and thirty-nine BD patients meeting criteria for a depressive episode were included in the study. SUD and PD were diagnosed according to structured interviews. Personality dimensions were evaluated by the Temperament and Character Inventory. Depressive severity over time was evaluated by the Hamilton Rating Scale for Depression. Neither PD nor SUD influenced the outcome of depression. Variables independently associated with a poor outcome were a high baseline severity and high scores for the temperamental trait of Harm Avoidance. Though several limitations characterize the present study, neurotic personality traits seem to be associated with a slower recovery from depressive symptoms in BD, independently from their initial severity.