Incidence and predictors of drug-induced parkinsonism in older psychiatricpatients treated with very low doses of neuroleptics

The available literature suggests that a sizable proportion of patients pla ced on neuroleptics develop acute and subacute extrapyramidal side effects, including neuroleptic-induced parkinsonism (NIP). The presence of mild, sp ontaneous extrapyramidal signs in the elderly makes it difficult to accurat ely estimate the incidence of NIP in this subgroup of patients. We examined the incidence of NIP in 56 older, newly medicated, psychiatric patients. F ifteen age-comparable, unmedicated psychiatric patients underwent 2 assessm ents to estimate natural fluctuation in extrapyramidal signs, and 49 normal , healthy, elderly individuals were also studied to establish age-comparabl e norms for the assessment of parkinsonism. Potential pretreatment predicto r variables included instrumental measures of motor function, age, cognitiv e status, and psychiatric diagnosis. After controlling for spontaneous park insonism, 32% of patients met strict criteria for NIP after receiving an av erage of 43 mg/day chlorpromazine equivalents of a typical neuroleptic, Fac tors contributing to the development of NIP included older age, instrumenta lly derived tremor, baseline extrapyramidal signs, type of neuroleptic, and severity of dementia, The use of risperidone in a small sub-sample was not associated with; NIP. These findings indicate that even after controlling for spontaneous extrapyramidal signs at baseline and their natural fluctuat ions, there is a substantial risk of NIP in older patients who are treated with very low doses of typical neuroleptics.