The relationship of the cholinergic system of the brain to memory and cognitive functions was studied in human subjects by the use of scopolamine, methscopolamine bromide, and physostigmine. A battery of tests evaluated immediate memory span, memory storage (acquisition), and retrieval, as well as nonmemory cognitive ability. Subjects receiving scopolamine showed impairment of memory storage and possibly retrieval despite normal immediate memory span; nonmemory cognitive functions were also impaired. Neither methscopolamine (a peripherally acting scopolamine analogue) nor physostigmine (a centrally acting anticholinesterase agent) produced any significant changes in memory or other cognitive functions.
Comparisons of the memory and cognitive deficits induced by scopolamine with the performance of aged subjects revealed a marked similarity of pattern. The possible theoretical explanations for the behavioral similarity seen with central cholinergic blockade and normal aging are discussed.
Drachman DA, Leavitt J. Human Memory and the Cholinergic SystemA Relationship to Aging?. Arch Neurol. 1974;30(2):113–121. doi:10.1001/archneur.1974.00490320001001