“To date, clinicians have little evidence-based data to guide their approach to the treatment of acute bipolar II depression,” Trisha Suppes, M.D., Ph.D., of Stanford University and colleagues wrote. “[O]ur results support the possibility that, unlike in bipolar I patients, an antidepressant monotherapy may be appropriate and carries few risks in some patients with bipolar II disorder.”
The researchers randomly assigned 142 patients with bipolar II disorder who were experiencing a major depressive episode to sertraline, lithium, or lithium/sertraline combination therapy for 16 weeks. To evaluate dosing, side effects, and mood, patients were seen weekly for six weeks and then every two weeks for 10 weeks.
Of the 142 participants, 20 (14%) experienced a switch at some point during the study period. Seventeen (12%) developed hypomania, and three (2%)–one in each treatment arm–developed severe hypomania. No participant switched to a manic episode or was hospitalized for switching to hypomania. Of the 20 participants who experienced a switch, 11 (55%) switched within the first four weeks of treatment and 15 (75%) within the first five weeks.
Although there were no significant differences in response rates between treatment groups, the pattern of treatment response differed between rapid and nonrapid cyclers: the rapid cyclers showed no difference across the three regimens, whereas the nonrapid cyclers had a significantly lower response to the lithium/sertraline therapy. Additionally, patients in the combination group had a greater overall dropout rate.
While Suppes and colleagues acknowledged several limitations of the study, including that they cannot be certain of whether switch rates are attributable to treatment or natural course of illness, they noted that the results underscore the importance of closely monitoring patients during the first five weeks of treatment.
Additionally, “As there was a higher dropout rate in the lithium/sertraline group with no significant response advantage, combination therapy may be the least desirable option for short-term treatment,” they added.
For more information, see the Psychiatric News article “Combining Quetiapine, Lamotrigine May Reduce Bipolar Depression.”