Risk factors for drug-induced parkinsonism in tardive dyskinesia patients.

Using multivariate statistical analyses, the authors identified risk factors for development of drug-induced parkinsonism (DIP) in 66 tardive dyskinesia (TD) patients. Older age, recent use of neuroleptics, shorter duration of past neuroleptic exposure, and severity of TD were associated with increased risk of DIP. The clinician should devise treatment strategies in anticipation of the occurrence of DIP regardless of the presence or absence of TD, especially in older patients. New models for the pathophysiology of the two disorders are needed.