Depression: The Shroud of Heterogeneity

Over the past several decades, depression has emerged as a major public health problem. Yet depression has not always represented such a prominent psychiatric condition, and the term depression has harbored different meanings over time. One widely agreed upon way of explaining such variation in what depression implies has been to describe depression as being heterogeneous. In the present article, depression is examined in relation to different types of heterogeneity, particularly with regard to the concept of a syndrome. The consequences of various meanings of heterogeneity for understanding the nature of depression are then explored. Finally, we speculate on the implications for the future of depression research and practice.