OBJECTIVE: To pursue the suggested increased incidence of bipolar disorder by examining for a cohort effect in the proportional representation of Bipolar Disorder in two independent clinical samples of depressed patients. METHOD: Assessment of polarity status was undertaken with some consistency over defined collection periods in two independent samples. RESULTS: The lifetime proportional rates of bipolar disorder declined with age from some 60% to 30% in both samples. CONCLUSIONS: The strikingly similar age-related pattern in both samples and the linear trajectory support a cohort effect where the incidence of bipolar disorder may be increasing disproportionately in younger individuals.
OBJECTIVE: To pursue the suggested increased incidence of bipolar disorder by examining for a cohort effect in the proportional representation of Bipolar Disorder in two independent clinical samples of depressedpatients. METHOD: Assessment of polarity status was undertaken with some consistency over defined collection periods in two independent samples. RESULTS: The lifetime proportional rates of bipolar disorder declined with age from some 60% to 30% in both samples. CONCLUSIONS: The strikingly similar age-related pattern in both samples and the linear trajectory support a cohort effect where the incidence of bipolar disorder may be increasing disproportionately in younger individuals.