Are bipolar mood symptoms affected by the phase of the menstrual cycle?

Background: Evidence suggests gender differences may exist in bipolar disorder, and a review of the literature shows that more women than men may experience rapid-cycling bipolar disorder. The issues contributing to these gender differences are unknown; a number of case reports have indicated the possibility of mood changes secondary to hormonal influences during the menstrual cycle. We sought to examine the relationship between bipolar disorder and menstrual cycle-related mood changes. To our knowledge, this is one of the largest samples in the literature addressing this issue. Methods: Outpatient women with bipolar disorder I, bipolar disorder II, and not otherwise specified (NOS), between the ages of 18 and 45, were evaluated. The National Institute of Mental Health Life Chart Method-p (NIMH-LCM-p) was used for daily mood ratings of depression and mania. Repeated measures of ANOVA and t tests were conducted separately for depressive and for manic symptom scores. Results: One hundred nineteen women met the age criterion, and only 41 women met the rest of the inclusion criteria. In this sample of 41 women, there was no significant relationship between phases of the menstrual cycle (early and late follicular and early and late luteal phases) and changes in depression or mania. In an exploratory examination, 8 of 41 women showed a numerically higher mean depression score in the luteal phase than in the follicular phase; 5 of 41 women showed a numerically higher mean mania score in the luteal phase than in the follicular phase of the menstrual cycle. Conclusions: Different phases of the menstrual cycle were unrelated to depression and mania in a heterogeneous group of women with bipolar disorder. Prospective studies are needed to identify a vulnerable subpopulation in a homogeneous clinical sample.