Depression and associated physical diseases and symptoms.
Depression can occur in association with virtually all the other psychiatric and physical diagnoses. Physical illness increases the risk of developing severe depressive illness. There are two broadly different mechanisms. The most obvious has a psychological or cognitive mechanism. Thus, the illness may provide the life event or chronic difficulty that triggers a depressive episode in a vulnerable individual. Secondly, more specific associations appear to exist between depression and particular physical disorders. These may turn out to be of particular etiological interest. The best examples are probably stroke and cardiovascular disease. Finally, major depression, but especially minor depression, dysthymia, and depressive symptoms merge with other manifestations of human distress with which patients present to their doctors. Such somatic presentations test the conventional distinction between physical and mental disorder and are a perennial source of controversy.