Association of diabetes with dyskinesia in older psychosis patients.

RATIONALE: Older patients treated with antipsychotics are more likely to develop tardive dyskinesia (TD) than younger individuals. Advanced age is also an important risk factor for diabetes, which may be associated with TD. These observations suggest that older diabetic patients may be particularly vulnerable to developing TD.
OBJECTIVE: To examine whether older psychosis patients with diabetes exhibit more severe dyskinesia than well-matched patients without diabetes and to test whether there are differences in dyskinesia severity between diabetic patients treated with conventional versus atypical antipsychotics versus those not taking antipsychotic medications.
METHOD: Sixty-one psychosis patients with diabetes and 122 case-matched non-diabetic comparison patients were studied. Observer-based and quantitative instrumental measures were administered to assess prevalence and severity of dyskinesia. Raters were unaware of patients' diabetes status.
RESULTS: Diabetic patients exhibited significantly more severe TD than non-diabetic comparison patients. Groups did not differ in terms of severity of parkinsonism. Significantly more diabetic (27.9%) than non-diabetic (14.6%) patients met research diagnostic criteria for TD. Diabetic patients treated with atypical antipsychotics at the time of assessment had significantly more severe TD than all other patient subgroups, including patients treated with conventional antipsychotics. Results from the instrumental measures of force steadiness were consistent with observer-based severity ratings.
CONCLUSION: The deleterious effect of diabetes on TD in the absence of any effect of parkinsonism supports preclinical studies of glucose-related dopamine hyperfunction and has implications for the pharmacologic management of psychosis in patients with pre-existing diabetes.