Effects of amantadine and trihexyphenidyl on memory in elderly normal volunteers

Anticholinergic drugs impair one's ability to learn new material, even at routine clinically used doses. During the trihexyphenidyl phase of this double-blind crossover trial, elderly normal subjects complained of confusion and memory impairment and demonstrated a pattern of deficits in memory function compatible with that previously reported to result from anticholinergic drugs. The subjects neither complained of nor demonstrated memory impairment while taking amantadine, which is believed to exert its pharmacological effects upon extrapyramidal disorders via dopaminergic mechanisms and does not appear to be associated with memory impairment. Anticholinergic drugs should be avoided whenever possible in the elderly and especially in those suffering dementia.