A Prospective Investigation of the Natural History of the Long-term Weekly Symptomatic Status of Bipolar II Disorder

This is the first prospective longitudinal study, to our knowledge, of the natural history of the weekly symptomatic status of bipolar II disorder (BP-II).

Weekly affective symptom status ratings for 86 patients with BP-II were based on interviews conducted at 6- or 12-month intervals during a mean of 13.4 years of prospective follow-up. Percentage of weeks at each symptom severity level and the number of shifts in symptom status and polarity were examined. Predictors of chronicity for BP-II were evaluated using new chronicity measures. Chronicity was also analyzed in relation to the percentage of follow-up weeks with different types of somatic treatment.