AGE-RELATED-CHANGES IN RODENT CORTICAL ACETYLCHOLINE AND COGNITION - MAIN EFFECTS OF AGE VERSUS AGE AS AN INTERVENING VARIABLE

Evidence from aged and demented humans has stimulated research on the effects of age on the integrity of cortical cholinergic afferents in r odents. However, a comprehensive review of the available data does not consistently support the hypothesis that normal aging in rodents robu stly affects the function of basal forebrain cholinergic projections t o the cortex. These data indicate the limited significance of age as a n independent experimental variable in research on age-related changes in cortical acetylcholine and associated behavioral or cognitive func tions. Alternatively, recent studies demonstrated that normal aging in rodents potently interacts with the consequences of experimental mani pulations of this system. Thus, aging acts as an intervening variable in experiments designed to elucidate age-related changes in the vulner ability and restorative capacity of this neuronal system after injury and degenerative processes. Investigations of the interactions between the effects of age and the capacity of the cholinergic systems to res pond to detrimental processes reveal robust consequences of aging on c ortical acetylcholine and the cognitive functions mediated by this neu ronal system. (C) 1998 Elsevier Science B.V. All rights reserved.