Course of BD Course in Adults

There have been a growing number of prospective studies of the course of BD in adults identified in treatment settings in the United States and Europe. Table 2.1 summarizes the methods and major findings of the ten prospective studies with greater than 1 year follow-up with direct assessments of patients. Many of these studies involved multicenter collaborative efforts in order to recruit large numbers of patients and increase the representativeness of the samples. These include the National Institutes of Mental Health (NIMH) Collaborative Depression Study (CSD),^6-8 the Stanley Foundation Bipolar Network (SFBN),⁹ the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) study,¹⁰ and the European Mania in Bipolar Evaluation of Medication study (EMBLEM) that included investigators in four European countries (Denmark, Germany, Spain, and Switzerland),¹¹ and a number of other studies in the United States, Europe, and Australia.^12-19 The duration of follow-up ranged from 2 years in studies in Australia¹⁹ and the STEP-BD study;¹⁰ to 4 years in the EMBLEM study,¹¹ a recent Austrian BD sample,¹² and a systematic county-wide study of first episode psychotic BD patients;¹³ to 7 years in the Stanley Foundation BP Course study;⁹ and to several decades in the Collaborative Study of Depression in the United States,^6-8 a cohort of inpatients with BD in the United States,¹⁴ and a Swiss hospital cohort that has now been followed for nearly half a decade.^15-17 The samples in these studies have generally been identified in specialty treatment settings, with some focusing solely on inpatients,^12-14,17,18 whereas others recruited broader samples of both inpatients and outpatients.^8-11,19 The study of first-episode psychosis in Suffolk County, New York, by Bromet et al.¹³ has the only population-based sample of first-incident treated cases.

Rich information on the precursors and sequelae of BD has also been obtained from large population registries in Denmark,²⁰ Sweden,²¹ and the Netherlands.²² Although the lack of direct interview information precludes evaluation of specific clinical features of episodes, these studies can provide valuable data that complement clinical course studies through linked registries that provide data on premorbid risk factors, and correlates and indices of outcome and course. There are also a few prospective community studies, such as the Zurich Cohort Study²³ and the NEMESIS study,²⁴ that also investigated the longitudinal stability of mania/hypomania. More recently, Baek et al.²⁵ assessed the stability of unipolar mania in the 3-year follow-up of a large US community-based sample who participated in the National Epidemiologic Survey on Alcohol and Related Conditions.