Motor and Cognitive Aging in a Nonhuman Primate Model

Abstract

Changes in motor function may accompany or predict cognitive decline and onset of dementia. Therefore regular monitoring of motor function may help to provide early detection of incipient cognitive impairment at an early stage when intervention maybe most effective. However, the relationships among motor and cognitive function during aging are not well understood, and it is not clear which measures of motor function may be best correlated or predictive of cognitive status. Furthermore, disruption of sleep and circadian rhythms is common in the elderly and may contribute to, or be correlated with, both motor and cognitive impairment. Animal models can provide an efficient means of testing these relationships in a highly controlled environment and exploring underlying neurobiological mechanisms. In particular, nonhuman primates have cognitive abilities most similar to humans, and show similar trajectories of motor and cognitive decline as they age. However, they can be maintained under carefully controlled environmental conditions including temperature, diet, medication, photoperiod and exposure to sex steroids, thereby eliminating major variables that often bias human studies. This study involves a cohort of aging female rhesus monkeys that already have been trained to perform several assessments of cognitive and motor function and will test these hypotheses: 1) that cognitive function, in particular spatial working memory and recognition memory, are correlated with measures of motor function, including locomotion (gait speed), fine motor skills, simple reaction time and activity levels in aging rhesus monkeys; 2) that both cognitive and motor functions are inversely correlated with perturbed circadian activity and sleep fragmentation; and 3) will also compare measures of activity, locomotion and motor function obtained with different technologies and validate them in comparison to video monitoring.