Symptoms of depression in Parkinson's disease.

20, not yet severely disabled, drug-free patients with Parkinson's disease were investigated with regard to their motor deficit and mood disturbances. Global scores of depression indicated a high depressive morbidity which did not correlate with the severity of parkinsonism and which could not be adequately explained by physical disability. The apathic syndrome had a close relationship to the severity of parkinsonism. In contrast, the somatic-depressive syndrome did not show such a relationship. Patients predominantly affected by tremor felt subjectively better than the others. These facts demonstrate that it is necessary to break down the complex syndromes of parkinsonism and depression into more elementary dysfunctions in order to evaluate their mutual interdependence.