Age-related cognitive deficits in rhesus monkeys mirror human deficits on an automated test battery

Aged non-human primates are a valuable model for gaining insight into mechanisms underlying neural decline with aging and during the course of neurodegenerative disorders. Behavioral studies are a valuable component of aged primate models, but are difficult to perform, time consuming, and often of uncertain relevance to human cognitive measures. We now report findings from an automated cognitive test battery in aged primates using equipment that is identical, and tasks that are similar, to those employed in human aging and Alzheimer's disease (AD) studies. Young (7.1+/-0.8 years) and aged (23.0+/-0.5 years) rhesus monkeys underwent testing on a modified version of the Cambridge Automated Neuropsychological Test Battery (CANTAB), examining cognitive performance on separate tasks that sample features of visuospatial learning, spatial working memory, discrimination learning, and skilled motor performance. We find selective cognitive impairments among aged subjects in visuospatial learning and spatial working memory, but not in delayed recall of previously learned discriminations. Aged monkeys also exhibit slower speed in skilled motor function. Thus, aged monkeys behaviorally characterized on a battery of automated tests reveal patterns of age-related cognitive impairment that mirror in quality and severity those of aged humans, and differ fundamentally from more severe patterns of deficits observed in AD.