NEUROLEPTIC DRUG EXPOSURE AND TREATMENT OF PARKINSONISM IN THE ELDERLY - A CASE-CONTROL STUDY

PURPOSE: Despite the widespread use of neuroleptic medications for the elderly, little is known about the frequency of treatment for drug-in duced parkinsonian syndromes in this age group, particularly with L-do pa-type drugs, which are more appropriate for the treatment of true id iopathic Parkinson's disease. PATIENTS AND METHODS: We identified 3,51 2 patients aged 65 to 99 enrolled in a large state Medicaid program wh o were newly prescribed a drug to treat parkinsonian symptoms. Control s were comparable program enrollees of similar age who had not been pr escribed an antiparkinsonian drug. In a case-control study, we evaluat ed the use of neuroleptic drugs in the 90 days before initiation of an tiparkinsonian therapy. RESULTS: Patients taking neuroleptics were 5.4 times more likely to begin antiparkinsonian medication than were nonu sers (95% confidence interval [CI] 4.8 to 6.1). They also had a greate r than two-fold increase in risk of beginning therapy with a dopaminer gic drug specific for idiopathic Parkinson's disease, not generally in dicated for treatment of drug-induced parkinsonism (adjusted odds rati o 2.2, 95% CI 1.9 to 2.7). Clear dose-response relationships were demo nstrated, as were differences among neuroleptics. Among all patients s tarted on dopaminergic drugs in this population, 37% of such therapy w as attributable to prior neuroleptic use. Continuation of the neurolep tic persisted in 71% of patients so treated. CONCLUSION: Neuroleptic u se is a common cause of extrapyramidal dysfunction in the elderly, and the side effect is frequently treated by adding an anticholinergic or dopaminergic drug to the regimen. The use of anticholinergic drugs pr esents risks of additional drug side effects; the use of dopaminergic drugs, generally not appropriate for drug-induced parkinsonian syndrom e, suggests that extrapyramidal neuroleptic side effects may often be mistaken for idiopathic Parkinson's disease in older patients.