A growing body of evidence suggests that life events may have an impact on the onset and course of bipolar spectrum disorders (Johnson & Kizer, 2002; Johnson & Roberts, 1995). For the most part, these studies have found that bipolar individuals experienced increased stressful events prior to onset or subsequent episodes of their disorder. Moreover, most have found that the manic/hypomanic, as well as the depressive, episodes of bipolar individuals were preceded by negative life events (Johnson & Roberts, 1995). However, several methodological limitations make interpretation of many of these studies difficult. First, many studies used retrospective rather than prospective designs. Retrospective designs have the problems that recall of events may decrease over time and become biased by the individuals' attempts to explain the cause of their disorder to themselves (Brown, 1974,1989). Second, many studies do not distinguish between the depressive and manic/hypomanic episodes of bipolar individuals; thus, it is unclear whether stressful events contribute to the onset of mania and depression. Third, several do not include a control group. Fourth, some use admission to the hospital or the start of a treatment regimen as the time of episode onset, which does not necessarily correspond well with the actual date of episode onset. Finally, many studies have failed to differentiate between events that are independent of or dependent on people's behavior, a distinction of considerable importance given the chaotic lifestyles of those with bipolar disorders. We review the more limited retrospective studies first, followed by the stronger prospective studies.
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