1. ¹Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA
2. ²The International Mood Center, University of California San Diego and VA Psychiatry Service, San Diego, CA, USA
3. ³Zurich University Psychiatric Hospital, Zurich, Switzerland
4. ⁴The Department of Psychiatry and Behavioral Sciences, University of Texas Medical Branch, Galveston, TX, USA
5. ⁵The Intramural Research Program, Section on Developmental Genetic Epidemiology, National Institute of Mental Health, Bethesda, MD, USA
6. ⁶The Department of Health Care Policy, Harvard Medical School, Boston, MA, USA

Correspondence: Dr RC Kessler, Department of Health Care Policy, Harvard Medical School, 180 Longwood Avenue, Boston, MA 02115, USA. E-mail: kessler@hcp.med.harvard.edu

Received 20 March 2009; Revised 8 May 2009; Accepted 27 May 2009; Published online 30 June 2009.

Abstract

Virtually nothing is known about the epidemiology of rapid cycling bipolar disorder (BPD) in community samples. Nationally representative data are reported here for the prevalence and correlates of a surrogate measure of DSM-IV rapid cycling BPD from the National Comorbidity survey Replication (NCS-R), a national survey of the US household population. DSM-IV disorders were assessed in the NCS-R with the WHO Composite International Diagnostic Interview (CIDI). Although the CIDI did not assess rapid cycling, it did assess the broader category of 12-month BPD with frequent mood episodes (FMEs), having at least four episodes of mania/hypomania or major depression in the 12 months before interview. Roughly one-third of NCS-R respondents with lifetime DSM-IV BPD and half with 12-month BPD met criteria for FME. FME was associated with younger age-of-onset (of BP-I, but not BP-II) and higher annual persistence (73% of the years since first onset of illness with an episode) than non-FME BPD. No substantial associations of FME vs non-FME BPD were found with socio-demographics, childhood risk factors (parental mental disorders, other childhood adversities) or comorbid DSM-IV disorders. However, FME manic episodes had greater clinical severity than non-FME episodes (assessed with a fully structured version of the Young Mania Rating Scale) and FME hypomanic episodes had greater role impairment than non-FME episodes (assessed with the Sheehan Disability Scales). Whether these indicators of severity merely reflect attenuated effects of rapid cycling or independent effects of sub-threshold rapid cycling warrants further study given the high proportion of lifetime cases who met criteria for FME.