Sadness as an integral part of depression.

Sadness is considered by numerous authors to be a core symptom of depression. Currently, many arguments exist for its particular importance in depressed patients. Sadness makes up part of the various definitions of the depressive syndrome, even if its presence is not required for diagnosis. Furthermore, it is closely linked to the other depressive symptoms, and has prognostic value, in particular for remission. The recognition and measurement of sadness seem important for therapeutic evaluation, in clinical studies, and in depressed patients at an individual level. This paper presents a selective review of some of the various aspects of sadness as an integral part of depression, and an examination of its links with a disease which is a major health concern.