Anticholinergic antiparkinsonian agents often cause side-effects including cognitive
impairment, dry mouth, and constipation while they diminish antipsychotic-induced
parkinsonian symptoms. The introduction of second generation antipsychotics (SGA) brought
fewer neurological side effects. However, anticholinergic coprescription rates are still as
high as 12-65% in patients on SGA that are much higher than the incidence of EPS reported in
clinical trials (3-20%). This apparently discrepancy is likely explained, in part, by the
established tradition of routine use of this medications. Older patients are particularly
sensitive to anticholinergic side-effects due to age-related changes in pharmacokinetics and
pharmacodynamics. In this study, we will examine the safety and benefits of reducing the dose
of a frequently prescribed anticholinergics, benztropine, on cognitive function,
extrapyramidal symptoms, and psychotic symptoms in older subjects with a primary psychotic
disorder.