Antidepressant risk in bipolar patients limited to monotherapy use

By Eleanor McDermid, Senior medwireNews Reporter

Antidepressants may cause problems in patients with bipolar disorder only when they are used in isolation, research suggests.

The findings, published in The American Journal of Psychiatry, indicate that antidepressants do not significantly increase the risk of mania if they are used in conjunction with a mood stabiliser.

“This is important because treatment options for bipolar depression are urgently needed”, say study author Mikael Landén (University of Gothenburg, Sweden) and colleagues.

“[P]atients with bipolar disorder spend most of their time in depressive episodes, and depressive symptoms are the leading cause of impairment and morbidity in bipolar patients.”

The findings disagree with those of a previous meta-analysis, but the researchers argue that the meta-analysis was probably confounded by indication, because of patients with severe disease being given multiple medications to control their symptoms. “In the present study, we circumvented the risk of confounding by indication by using a within-individual design, reducing confounding caused by differences in disorder severity”, they write.

The team used Swedish national registry data to identify patients with bipolar disorder who started antidepressant therapy following a year free of antidepressant treatment. The sample included 1117 patients who started on antidepressant monotherapy and 1641 who took a concurrent mood stabiliser.

Patients taking an antidepressant as monotherapy were 2.83 times more likely to develop mania during the first 3 months of treatment than they were in the equivalent 3 months of the preceding year in which they were not taking an antidepressant.

By contrast, there was no increased risk of mania among patients who were taking a concurrent mood stabiliser, despite these patients presumably having more severe bipolar disorder. Neither group had an increased risk during months 4 to 9 after starting treatment.

“This study thus lends further support to the need for caution when using antidepressant monotherapy to treat bipolar depressive episodes because of the risk of treatment-emergent mania”, say the researchers.

They note that antidepressant monotherapy is advised against in current guidelines, yet nearly 35% of the patients in their study were prescribed antidepressant monotherapy. “Thus, our results are important for future guidelines, but probably even more important for reminding clinicians of the importance of [current] guidelines”, concludes the team.

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