Abstract
Psychiatric phenomena can usefully be studied by the establishment of syndromes which can then be used as the basis of treatment and so on. The delineation of syndromes of affective illness has a long history. It implies a distinction from normal lowering of mood. This distinction has been related to the concepts of diathesis and disregulation. However, studies of psychosocial adversity have not been able to add to the concept of affective illness. It is concluded that for it to be maintained that the distinction between simple distress and affective illness is useful, major aetiological differences must be demonstrated. It is likely that this can only be done through multidisciplinary studies.