The Long-term Natural History of the Weekly Symptomatic Status of Bipolar I Disorder

Background: To our knowledge, this is the first prospective natural history study of weekly symptomatic status of patients with bipolar I disorder (BP-I) during longterm follow-up.Methods: Analyses are based on ongoing prospective follow-up of 146 patients with Research Diagnostic Criteria BP-I, who entered the National Institute of Mental Health (Bethesda, Md) Collaborative Depression Study from 1978 through 1981.Weekly affective symptom status ratings were analyzed by polarity and severity, ranging from asymptomatic, to subthreshold levels, to fullblown major depression and mania.Percentages of follow-up weeks at each level as well as number of shifts in symptom status and polarity during the entire follow-up period were examined.Finally, 2 new measures of chronicity were evaluated in relation to previously identified predictors of chronicity for BP-I.Results: Patients with BP-I were symptomatically ill 47.3% of weeks throughout a mean of 12.8 years of followup.Depressive symptoms (31.9% of total follow-up weeks) predominated over manic/hypomanic symptoms (8.9% of weeks) or cycling/mixed symptoms (5.9% of weeks).Subsyndromal, minor depressive, and hypomanic symptoms combined were nearly 3 times more frequent than syndromal-level major depressive and manic symptoms (29.9% vs 11.2% of weeks, respectively).Patients with BP-I changed symptom status an average of 6 times per year and polarity more than 3 times per year.Longer intake episodes and those with depression-only or cycling polarity predicted greater chronicity during long-term follow-up, as did comorbid drug-use disorder.