Prevalence and correlates of parkinsonism in an institutionalized population of geriatric patients with chronic schizophrenia.

Background: Geriatric patients with chronic schizophrenia are at increased risk for parkinsonism and cognitive impairment, but the relationship between the two has been insufficiently studied.

Objective: (1) To determine the prevalence of parkinsonism in a cohort of institutionalized geriatric patients with chronic schizophrenia (N=79). (2) To examine the relationship of parkinsonism to potentially relevant variables including cognitive functioning, positive and negative symptoms, sex, age, age at first hospitalization, psychopharmacological regimen and tardive dyskinesia (TD).

Methods: Tremor, rigidity and bradykinesia were rated on a five-point severity scale. Clinically significant parkinsonism was defined by the unambiguous presence of at least two of those signs. TD was assessed with the Modified Simpson Dyskinesia Scale. Schizophrenic symptoms were rated with the Positive and Negative Syndrome Scale, and cognitive functioning with the Mini-Mental State Examination and the Consortium to Establish a Registry for Alzheimer's Disease battery.

Results: The prevalence of parkinsonism was 19% and was significantly higher in women than in men. Age was a significant predictor of parkinsonism. Independent of age, bradykinesia was significantly correlated with MMSE, fluency and naming. Tremor, rigidity and medication status did not correlate with any cognitive variable assessed. Cognitive measures did not differ between subjects meeting and not meeting criteria for clinically significant parkinsonism. Rigidity and bradykinesia were significantly correlated with negative symptoms but no parkinsonism sign correlated with positive symptoms. Twelve subjects received ratings consistent with both TD and parkinsonism; however, no parkinsonian variable predicted the co-occurrence of TD.

Conclusions: The present correlations suggest potential overlap among the neural substrates for bradykinesia, cognitive impairment and negative symptoms; however, further research is required to clarify that issue.