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

Objective: The authors studied the incidence of tardive dyskinesia in elder ly institutionalized patients with dementia being treated with risperidone. Method: After participating in a 12-week multicenter double-blind study dur ing which they received placebo or one of three doses of risperidone, 330 p atients (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 flex ible doses of risperidone. Persistent emergent tardive dyskinesia was defin ed according to scores on the dyskinesia subscale of the Extrapyramidal Sym ptom 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 incid ence of persistent emergent tardive dyskinesia among the 255 patients witho ut dyskinesia at baseline was 2.6%. Patients with dyskinetic symptoms at ba seline experienced significant reductions in the severity of dyskinesia. Pa tients who received 0.75-1.5 mg/day of risperidone showed a significant imp rovement 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 tha n 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.