Beneficial effect of donepezil in the treatment of elderly patients with tardive movement disorders.

BACKGROUND: Tardive dyskinesia and other delayed-onset abnormal involuntary movement disorders may occur as a result of the use of psychotropic drugs. A distinction is usually made between classic tardive dyskinesia (TD) (orobuccal-lingual-facial) and tardive dystonia, tardive tremor (TT), tardive akathisia, and other related syndromes. In spite of the development of atypical antipsychotics with fewer side effects, tardive movement disorders nevertheless continue to present a significant clinical and therapeutic challenge. Several reports have suggested that donepezil may be helpful in the treatment of TD. METHOD: A preliminary study was conducted of 7 patients (5 women and 2 men) enrolled over a period of 6 months who had been experiencing TT for a period of at least 1 year. The ages of the patients ranged from 64 to 79 years, and all patients were on stable antipsychotic therapy. Donepezil was added to their usual treatment for 8 weeks. The severity of patients' extrapyramidal symptoms was assessed using the tremor subscale of the Simpson-Angus Scale (SAS) and self-rated with a modification of the Clinical Global Impressions scale, the Subjective Clinical Improvement Impression scale. The clinical response was evaluated by comparing the rating scores at baseline prior to donepezil treatment and every 2 weeks thereafter. RESULTS: The addition of donepezil (up to 10 mg/day) was associated with a clinically significant improvement (from 37.5% to 63.6%) on the SAS tremor subscale following 4 weeks of therapy. Only 1 patient discontinued follow-up due to side effects. CONCLUSION: The results suggest that donepezil may be effective in the treatment of TT, and this finding should be evaluated further by a randomized controlled study.