People with a type of bipolar disorder, known as bipolar II, respond similarly to treatment with either antidepressants or mood stabilizers, or a combination of the two, finds a new study published in the American Journal of Psychiatry in March.

Despite the similar response, however, people who received the combination treatment had a higher rate of dropping out than those who received only one medication. This suggests the combination therapy, which is the most commonly recommended treatment in clinical practice, may be the least desirable option for some patients, the researchers said.

People with bipolar II disorder experience depressive episodes that occasionally switch to hypomanic episodes, but unlike people with bipolar I disorder, they don’t experience full-blown manic episodes. (Mania is a state of elevated arousal and heightened mood; hypomania is a weaker version of the manic state.)

Treatments for bipolar II disorder vary. There are only a few treatment guidelines aimed at this type of bipolar disorder. Most guidelines suggest using the same medications as for bipolar I disorder. Clinicians routinely prescribe antidepressants along with a mood stabilizer, but there’s a concern that using antidepressants might increase the risk of the patient “switching over” to a hypomanic state.

In the study, the researchers examined how 142 patients responded to three different blinded treatments: one group received the SSRI antidepressant sertraline, while another group received mood stabilizer lithium, and a third group received a combination of the two.

Over 16 weeks of study, researchers tracked participants’ mood and assessed the number of mood switches. Overall, 20 participants (14 percent) experienced switches to hypomania, most of which occurred within the first five weeks of treatment.

Switch rates did not differ among the three treatment groups. This finding supports the idea that, unlike in bipolar I patients, an antidepressant treatment alone may be appropriate and safe for some patients with bipolar II disorder, the researchers said.

Response to treatment was high across all groups. Fifty-seven percent of all participants showed considerable improvements of symptoms by the end of the study.

Overall, about 56 percent of participants did not finish the study. About 23 percent of participants dropped out due to medication side effects, the risk of which did not differ significantly among groups.

However, the likelihood of dropping out for any reason was significantly higher in the combination treatment group: About 70 percent of participants in that group dropped out, compared with 42 percent in the sertraline group and 55 percent in the lithium group.

 

The findings suggest that treatment with lithium alone, or sertraline alone may be a better option for some patients than combination therapy.

The research team was led by Trisha Suppes, M.D., Ph.D. (two-time NARSAD Young Investigator grantee), Lori Altshuler, M.D., and Susan McElroy, M.D. The late Dr. Lori Altshuler, who was the first author of this paper, died in November, 2015. Dr. Altshuler was a three-time NARSAD Grantee, as well as the 2006 Colvin Prizewinner for Outstanding Achievement in Mood Disorders Research.