Parkinson's disease, depression, and ECT: a review and case study.

The author reviews the association between Parkinson's disease and depression and presents evidence to support the hypothesis that depression may be not only reactive but biochemically related to the disease. A psychotically depressed patient with parkinsonism responded positively to ECT as shown by improvement on a depression rating scale, two extrapyramidal rating scales, and handwriting samples. The beneficial effect on parkinsonian signs occurred before the improvement in depression, which suggests that ECT has a specific antiparkinsonian effect. Possible explanations for this observation based on biochemical theories of depression are discussed.