Nonhuman Primate Models of Cognitive Aging

Abstract

Nonhuman primates are indispensable for the study of aging processes. Like other animals, they permit us to observe the effects of age in the absence of the confounds inherent in studies of human beings. Additionally, because they are phylogenetically close to humans and possess certain uniquely primate morpho- logical, endocrine, behavioral, and cognitive traits, they can provide data uniquely relevant to human aging. Among nonhuman primates, the rhesus monkey is by far the most widely studied in the context of aging, as verified in the large number of reviews that have summarized the studies on this species. To date, however, there is no published overview of the many other species of nonhuman primates in which age-related changes have been studied. This chapter is intended to fill that gap. Thus, we discuss results from a wide variety of prosimian, monkey, and ape species, ranging from the mouse lemur to the great apes. We include species about which a great deal is known as well as those, such as the gorilla and chimpanzee, on which only one or two studies have been conducted. For each species or group of species, we describe what is known about age-related changes in cognition, in the brain, and in patterns of reproductive senescence. We conclude that, although studies on the rhesus monkeys have provided the greatest depth of knowledge about cognitive aging processes, the many other primate species, with their wide variety of reproductive, morphological, and behavioral adaptations, can shed new light on the factors underlying age-related cognitive changes in our own species.