SSRIs as mood stabilizers for Bipolar II Disorder? A proof of concept study

Background: We have previously observed that prescription of some antidepressant class drugs (particularly the SSRIs) is associated with attenuation of the number, duration and severity of both high and low mood states in those with Bipolar II Disorder. We examined whether SSRIs are a mood stabilizer for Bipolar II Disorder. Method: We report a randomized, double-blind, placebo-controlled cross-over study lasting 9 months in a sample of 10 patients who had not had previous treatment with any antidepressant, antipsychotic or mood stabilizer drug. Results: Treatment with the SSRI led to a significant reduction in depression severity, percentage of days depressed or high, and percentage of days impaired, when compared with placebo. There was no indication that the SSRI led to a worsening of illness course. Limitations: Given the small sample size and a weighting to those with a rapid cycling condition, replication with a larger and more heterogeneous sample of those with Bipolar Disorder is required. Conclusions: This proof of concept study finds preliminary support for the potential utility of SSRIs in managing Bipolar II Disorder, with clear improvements in depression and impairment and some suggested benefit for hypomania.