Memory decline in the aged: treatment with lecithin and physostigmine.

Normal aged subjects were given lecithin and placebo for 5 weeks each in a double-blind crossover study. Supraspan tests of memory and learning failed to show any significant changes as a result of these treatments. Addition of a single IV infusion of physostigmine did not improve performance. These findings neither support nor weaken the "cholinergic hypothesis" of cognitive impairment in aging and dementia, but they imply that simple cholinergic hypofunction is unlikely.