Lifetime and 12-Month Prevalence of Bipolar Spectrum Disorder in the National Comorbidity Survey Replication

TLDR: This study presents the first prevalence estimates of the BPD spectrum in a probability sample of the United States, and finds subthreshold BPD is common, clinically significant, and underdetected in treatment settings.

Abstract: The estimated lifetime prevalence of bipolar disorder (BPD) in population surveys using structured diagnostic interviews and standardized criteria averages approximately 0.8% for BP-I and 1.1% for BP-II.1-8 Despite this comparatively low prevalence, BPD is a leading cause of premature mortality due to suicide and associated medical conditions such as diabetes and cardiovascular disease.9, 10 BPD also causes widespread role impairment.11, 12 The recurrent nature of manic and depressive episodes often leads to high direct as well as high indirect health care costs.13, 14 BPD might be even more burdensome from a societal perspective due to the fact that sub-threshold bipolar spectrum disorder has seldom been taken into consideration in examining the epidemiology of BPD. Bipolar spectrum disorder includes hypomania without major depression and hypomania of lesser severity or briefer duration than specified in the DSM and ICD criteria. Although the precise definitions are as yet unclear, recent studies suggest that bipolar spectrum disorder might affect as many as 6% of the general population.15, 16 However, bipolar spectrum disorder has not been studied previously in a nationally representative survey of the US. The purpose of the current report is to present the results of such a study based on analysis of the National Comorbidity Survey Replication (NCS-R).17 We estimate prevalence and clinical features of sub-threshold BPD in comparison to BP-I and BP-II.