Development and validation of the current concept of major depression.

The operational diagnostic criteria for major depression have remained more or less the same in the past 40 years. However, the threshold for the diagnosis fixed by operational definitions has been criticized for either being too high, excluding many depressive states which do not differ from currently defined major depression on several variables, or too low, so that the milder cases receiving the diagnosis do not respond to antidepressants better than to placebo. Furthermore, it has been stated that current operational criteria do not convey anymore the gestalt of the depressive syndrome, and that they lead to the inclusion under the heading of depression of several homeostatic responses to adverse life events. This paper reviews the development and validation of the current concept of major depression and identifies priorities for future research.