Double-blind donepezil-placebo crossover augmentation study of atypical antipsychotics in chronic, stable schizophrenia: a pilot study.

Thirteen outpatients with chronic but stable schizophrenia received donepezil and placebo augmentation of their maintenance antipsychotic medication regimen. Each subject received in a randomized, counterbalanced order 1) donepezil 5 mg for 6 weeks then donepezil 10 mg for six weeks and 2) placebo donepezil for 12 weeks. Serial ratings of the Positive and Negative Symptom Scale (PANSS) [Kay, S.R., Fiszbein, A., Opler, L.A., 1987. The positive and negative syndrome scale (PANSS) for schizophrenia. Schizophrenia Bulletin 13(2): 261-276] were performed by a trained rater blind to the donepezil order and condition: at baseline, 12 weeks and 24 weeks. On donepezil as compared to baseline or placebo, there was a significant improvement in PANSS negative scores (p=.018, n=13). These results are discussed with respect to other studies using cholinesterase inhibitors as an augmentation strategy in schizophrenia.