Twenty-one patients with Parkinson's disease and psychosis were included in
an open-label 8-week trial of olanzapine. Eight subjects had dementia. Six
subjects (29%) discontinued treatment prematurely because of drowsiness. D
elusions and hallucinations improved significantly, and 80% were rated as m
uch or very much improved. There was no worsening of parkinsonism or cognit
ion.