Clinical characterisation of dual depression and association with bipolarity features

Background. Substance use disorders often co-occur in individuals with major depression. This post hoc analysis of the BRIDGE-II-MIX study aims to examine the clinical characterisation of subjects with major depression and alcohol/sub-stance abuse in comorbidity, focusing on bipolarity features. Methods. This multicenter, cross-sectional study included 2811 subjects with a major depressive episode. Sociodemographic and clinical data, as well as psychiatric comorbidity and treatment received, were collected and compared between major depressive patients with (SUD) and without (N-SUD) current alcohol/substance abuse. Results. Of the total sample, 8.3% met the criteria for current alcohol/substance abuse. Bipolar disorder was diagnosed more frequently in the SUD group (41.9%) than in the N-SUD group (24.7%), as well as comorbidity with eating disorders, especially anorexia nervosa and bulimia nervosa (p<0.001), social phobia (p<0.001), and borderline personality disorder (p<0.001). In addition, SUD patients had more bipolar features than N-SUD patients, such as mixed features and early age at first depressive episode. SUD patients were also more likely than N-SUD patients to have (hypo)manic switches (p<0.001) and mood lability/irritability (p<0.001) in response to antidepressant treatment. Among current (hypo)manic symptoms, emotional/mood lability, grandiosity, and risky behaviour were most strongly associated with the presence of current alcohol/substance abuse. Conclusions. The presence of substance use disorder should always be carefully considered in individuals with MDE, especially in the presence of bipolar features such as affective instability, manic/mixed symptoms, suicidality, early age of onset of depression, and comorbidity with eating disorders, social phobia, or borderline personality disorder. When treating individuals with MDE and comorbid substance abuse, the potential risk of mood destabilisation with antidepressant use should be considered.