Objective: Cognitive impairment and negative signs are common in patients with schizophrenia. Up to 35% of elderly patients with schizophrenia fulfill the diagnostic criteria of dementia. Donepezil inhibits cholinesterase, thus enhancing cholinergic neurotransmission. We tested the efficacy of donepezil in elderly patients with chronic schizophrenia and severe cognitive impairment.

Method: Following baseline assessment, patients were randomly assigned to receive either donepezil or placebo. The dose was 5 mg daily for the first week and 10 mg for an additional 11 weeks. The procedure was repeated using the crossover compound. The Positive and Negative Symptom Scale (PANSS), Clinical Global Impression Scale (CGI) and Alzheimer Disease Assessment Scale – Cognitive subscale (ADAS-Cog) were used to assess the severity of symptoms, cognitive status and intervention effects.

Results: Twenty subjects were enrolled (15 females, five males), mean age 70.2 years (SD 6.5) and mean duration of disease 38.5 years (SD 9.3). A modest treatment effect was found for both placebo and donepezil treatment periods. No crossover effect was found. No statistical differences were demonstrated between the two treatment groups (CGI p = 0.37, PANSS p = 0.71, ADAS-Cog p = 0.86). Two patients died during the study period due to unrelated causes and one patient discontinued participation due to increased agitation.

Conclusion: Donepezil does not seem to improve negative signs and cognitive impairment in elderly patients with chronic schizophrenia.