Decreased verbal memory associated with anticholinergic treatment in Parkinson's disease patients.

The effects of chronic administration of the anticholinergic agent, benztropine mesylate (CogentinTM), on specific verbal memory were investigated as part of a placebo-controlled randomized double-blind crossover study to determine the clinical efficiency of CogentinTM as an adjuvant therapy with SinemetTM in Parkinson's disease. Twenty-nine males with clinically definite idiopathic Parkinson's disease participated in the trial. They were tested for acquisition of new word lists, and on four other cognitive tests before, during, between, and after two 10-week trial periods when they received either increasing doses of CogentinTM (maximum 2 mg) or placebo while on a maintenance dose of SinemetTM. Patients showed a statistically significant decrease (5--10%) in word list acquisition while on CogentinTM. The anticholinergic memory effect was unrelated to the degree of improved clinical efficacy of CogentinTM for the Parkinsonism, and to initial word list acquisition ability. Verbal memory findings indicate that chronic administration of an anticholinergic in even low therapeutic dosage may play an important role in memory function.