Cholinergic function in the aged brain: implications for treatment of memory impairments associated with aging

The cholinergic hypothesis of impaired memory in Alzheimer's disease has stimulated interest in cholinergic function of the brain in relation to the more common and less serious impairments of memory associated with normal (non-disease) aging. Unlike Alzheimer's disease, it is not clear whether normal aging results in a loss of cholinergic innervation to cerebral cortex and hippocampus, but prevailing evidence suggests that certain aspects of brain cholinergic function are diminished with advancing age. Human and animal data on the effects of aging on cholinergic systems of the brain are reviewed and are discussed in connection with the role these effects may play in the etiology and treatment of the learning and memory impairments associated with aging.