Low incidence of persistent tardive dyskinesia in elderly patients with dementia treated with risperidone

Objective: The authors studied the incidence of tardive dyskinesia in elderly institutionalized patients with dementia being treated with risperidone. Method: After participating in a 12-week multicenter double-blind study during which they received placebo or one of three doses of risperidone, 330 patients (mean age=82.5 years) with Alzheimer's, vascular, or mixed dementia were enrolled in a 1-year open-label study during which they received flexible doses of risperidone. Persistent emergent tardive dyskinesia was defined according to scores on the dyskinesia subscale of the Extrapyramidal Symptom Rating Scale. Results: The mean modal risperidone dose was 0.96 mg/day (SD=0.53), and the median length of risperidone use was 273 days. The 1-year cumulative incidence of persistent emergent tardive dyskinesia among the 255 patients without dyskinesia at baseline was 2.6%. Patients with dyskinetic symptoms at baseline experienced significant reductions in the severity of dyskinesia. Patients who received 0.75-1.5 mg/day of risperidone showed a significant improvement in psychopathologic symptoms over the 1-year period. Conclusions: Although there was no control group, the observed incidence of persistent tardive dyskinesia with risperidone seemed to be much lower than that seen in elderly patients treated with conventional neuroleptics. The average optimal dose of risperidone in elderly dementia patients was found to be 0.75-1.5 mg/day.