Pain as a symptom in depressive disorders and its relationship to platelet monoamine oxidase activity

144 depressed in-patients were rated by means of the Comprehensive Psychopathological Rating Scale (CPRS) and platelet monoamine oxidase (MAO) was determined. 49 per cent of the patients were found to have pain as a symptom, and 21 per cent were found to have more severe pain. The patients with more severe pain were found to have lower platelet MAO activity than the patients without pain or with slight pain. As platelet MAO activity may reflect the turn-over in the serotinergic systems in CNS it is hypothesized that patients with depressive disorders with pain as a symptom may have more pronounced disturbances in the serotinergic systems than patients without pain as a symptom.