THE COURSE OF DEPRESSION

Long-term naturalistic studies have changed the way we view depression. Whereas it was often previously viewed as an episodic disease, the past two decades of research have underscored the importance of understanding depression as a lifelong disease, with a number of possible courses. An appreciation of this longitudinal data is crucial to understanding all aspects of depression. Cross-sectional judgments of symptomatic severity provide limited prog-nostic information. A full understanding of a patient’s prog-nosis or likely treatment response also requires a longitudi-nal perspective. Which patient is likely to recover fully, and who will suffer from a chronic mood disorder? What length of treatment will be sufficient for such patients? Studies within the last decade have helped to shed light on these questions. This chapter examines some of these studies, and discusses their implications for our approach to depression. Limitations of the data will be discussed as well. THE CHANGE POINTS OF DEPRESSION Considerable confusion has resulted from the use of various terms to denote the different change points in the course of depression. Similar terms, such as ‘‘relapse’ ’ and ‘‘recur-rence’ ’ have been used interchangeably and inconsistently in different studies. As a result, the MacArthur Foundations Research Network on the Psychobiology of Depression (1) recommended using the following terms: 1. Episode, defined as a certain number of symptoms for a certain period of time. 2. Remission, defined as a period of time in which an indi-vidual no longer meets criteria for the disorder. In partia