Symptomatic menopausal transition and subsequent bipolar disorder among midlife women with major depression: a nationwide longitudinal study

Previous studies suggested that menopausal transition played an important role in the clinical course of major depression and bipolar disorder. However, the role of symptomatic menopausal transition in diagnostic conversion from major depression to bipolar disorder was still unknown. Using the Taiwan National Health Insurance Research Database, 50,273 midlife women aged between 40 and 60 years in 2002∼2008 with major depression were enrolled in our study and divided into two subgroups based on the presence (n = 21,120) or absence (n = 29,153) of symptomatic menopausal transition. Subjects who had subsequent bipolar disorder during the follow-up were identified. Midlife women with major depression and symptomatic menopausal transition had a higher incidence of the diagnostic conversion to bipolar disorder (7.3 vs. 6.6%, p = 0.003) than those with major depression alone. Cox regression analysis after adjusting for demographic data and psychiatric comorbidities further showed that symptomatic menopausal transition was associated with an increased risk of developing bipolar disorder (HR 1.14, 95% CI 1.07∼1.23) among midlife women with major depression. Sensitivity test after excluding the 1-year and 3-year observation exhibited the consistent findings (HR 1.18, 95% CI 1.09∼1.28; HR 1.20, 95% CI 1.08∼1.34). Midlife women with the dual diagnoses of major depression and symptomatic menopausal transition had an increased risk of the diagnostic conversion to bipolar disorder compared to those with major depression alone. Further studies may be required to investigate the underlying mechanisms among menopausal transition and the diagnostic conversion from major depression to bipolar disorder.