Left-sided Parkinson's disease is associated with greater anxiety and depression.

Seventeen patients with Parkinson's disease which was markedly asymmetric and worse on the right side of the body (RHP) were compared with 13 patients whose signs were worse on the left (LHP). The two groups of patients were well matched for age, duration of symptoms, disability, overall severity of signs, and medication. The mean scores on ratings of depression, using both a self-rating scale and semi-structured interview rating, were almost twice as great in the LHP group. The LHP group also had significantly more symptoms of anxiety. The prevalence of clinically significant psychopathology was increased about five fold in the LHP group compared with the RHP group. There was a close correlation between anxiety and depressive symptoms. The depression experienced by the patients was 'atypical', with relatively little anhedonia and evidence of a negative view of self, and prominent symptoms of anxiety. The best predictor of symptoms of depression and anxiety was a measure of social support and stress. They also correlated with the overall severity of Parkinson's disease.