Intra-episode hypomanic symptoms during major depression and their correlates

Recent studies have shown that 40-50% of major depressive disorders (MDD) may become bipolar with time. Intra-episode hypomanic symptoms in MDD may be a first step in this shift. The purpose of the present study was to find factors associated with intra-episode hypomanic symptoms in MDD. Two hundred and forty-three consecutive MDD outpatients were interviewed with the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (4th edn; DSM-IV), Clinician Version (SCID-CV), as modified by Benazzi and Akiskal (J. Affect. Disord. 2003; 73: 33-38). History of hypomania and presence of hypomanic symptoms during major depressive episode (MDE) were systematically assessed. Intra-episode hypomanic symptoms were defined as an MDE combined with three or more hypomanic symptoms, following Akiskal and Benazzi (J. Affect. Disord. 2003; 73: 113-122). Major depressive disorder with intra-episode hypomanic symptoms (MDD + H) was compared to MDD without hypomanic symptoms on classic bipolar validators. It was found that MDD + H (usually irritability, distractibility, racing thoughts, psychomotor agitation, and more talkativeness) was present in 32.5% of patients. Patients with MDD + H versus MDD had significantly lower age at onset, more atypical depressions, and more bipolar family history. Recurrences were not significantly different. Multivariate logistic regression found that bipolar family history and atypical depression were significantly and independently associated with MDD + H. Findings suggest that MDD + H may be associated with a bipolar vulnerability. Duration of illness and recurrences do not seem to be important for the onset of MDD + H. Bipolar genetic vulnerability seems to be required for onset of intra-episode hypomanic symptoms in MDD. Intra-episode hypomanic symptoms might be the first step of a process leading to the switch of MDD to bipolar disorders. Predicting the switch might have important treatment implications, because antidepressants used alone may worsen the course of bipolar disorders. Prospective studies are required to support these findings and hypotheses.