Depression and immunocompetence: a review of the literature.

Recent evidence suggests that there is a relationship between depression and immunity. On the basis of these studies, it has been argued that depressed mood may increase susceptibility to disease by means of aberrations occurring within the immune system. Empirical research investigating the relationship between depression and immunity is reviewed here. Studies examining both clinical and nonclinical manifestations of depression are discussed and evaluated. This review reveals that indexes of immunocompetence are lower among people exhibiting depressive symptomology and suggests that immune alterations may be more related to dysphoric mood than to specific situations or events. Alternative hypotheses accounting for links between depressed affect and altered immune states are provided, and suggestions for future research are offered.