Adjunctive lamotrigine therapy for patients with bipolar II depression partially responsive to mood stabilizers.

This naturalistic study explored long-term effectiveness of adjunctive lamotrigine therapy for bipolar II depression. We analyzed prospective data from 109 lamotrigine-treated outpatients with bipolar II depression inadequately responsive to mood stabilizers. Lamotrigine was added to prior treatment in a naturalistic fashion. Changes in depression severity were prospectively monitored for up to 52 weeks using a prospective mood chart and the Clinical Global Impressions-Bipolar Version-Severity (CGI-BP-S). Time to lamotrigine discontinuation during 52-week period was calculated using the Kaplan-Meier estimate. A significant reduction in the CGI-BP-S depression score was observed between baseline and week 52 with a large effect size. The discontinuation rates were 44.0% and 50.5% for the total sample and 14.3% and 22.9% for responders at 24 weeks and 52 weeks, respectively. A higher number of prior hospitalizations for depression and a history of attempted suicide were associated with poor response to adjunctive lamotrigine treatment. Sustained benefits of an open-label lamotrigine add-on were indicated in patients with bipolar II depression. Adjunctive usage of lamotrigine was safe and generally well-tolerated. The potential benefit of adjunctive lamotrigine treatment was suggested in patients with bipolar II disorder suffering from depressive symptoms. Large-scale controlled studies are needed to confirm the effectiveness of adjunctive lamotrigine therapy for bipolar II depression.