Bipolar Disorders: Mixed States, Rapid-Cycling, and Atypical Forms

383 Investigational strategies2. The 12-month period during which the patient satisfied the definition for rapidcycling includes episodes attributable to secondary factors such as antidepressantmedication, substance abuse, travel across time zones, and sleep apnea3. The subject would no longer meet criteria for rapid cycling if those phasesattributable to secondary factors were no longer countedPrimary rapid cycling1. Patient meets criteria for bipolar disorder2. Patient has experienced a period of rapid cycling characterized by at least fourepisodes or two complete cycles within a 12-month period3. At least two or more episodes were phases having occurred 6 months or moreafter discontinuing the exposure to all identifiable cycle-promoting factorsDefining a phase shift1. Phase change: the appearance of a new mood state with duration of 48 h or thatmeets the DSM-IV criteria for an episode2. As a continuous measure, the 48-h rule limits the range of phase changes permonth to between zero and 15. Even so, it can be problematic to reachconsensus on the total number of phase changes. Consensus is much easier toreach when the number of phases is collapsed to one of three categories: none,one, or more than oneACKNOWLEDGMENTDr Sachs’ work is supported in part by the Stanley Medical Research Institute.REFERENCESAkiskal, H. and Pinto, O. C. (1999). The evolving bipolar spectrum: prototypes I, II, III, and IV.Psychiatr. Clin. North Am., 22, 517–34.Alda, M., Grof, P., and Grof, E. (1998). MN blood groups and bipolar disorder: evidence ofgenotypic association and Hardy–Weinberg disequilibrium. Biol. Psychiatry, 44, 361–3.American Psychiatric Association (1994). Diagnostic and Statistical Manual of Mental Disorders,4th edn. Washington, DC: American Psychiatric Association.Baldessarini, R., Tondo, L., Floris, G. et al. (2000). Effects of rapid cycling on response to lithiummaintenance treatment in 360 bipolar I and II disorder patients. J. Affect. Disorder, 61, 13–22.