Agns Lacreuse of Emory University and her colleagues worked with 90 adult rhesus monkeys to test their spatial memories. The animals fell into three age groups ranging from young (less than 15 years old) to middle aged (between 15 and 20 years) to old (more than 20 years old). Rhesus monkeys "are useful in the study of possible sex differences in cognitive aging because they provide a model that is not confounded by sex differences in longevity or dementia," Lacreuse says. The researchers had the monkeys track the location of food hidden under 18 identical covers on a tray and found that young adult male monkeys performed the best at the task. This pattern of male supremacy did not hold across age groups, however: older males and females performed equally well. In addition, a second experiment with 22 monkeys indicated that training young female rhesus monkeys closes the gender gap. Whereas training had no impact on how well young males performed at locating the food, young females raised their abilities to match those of males after they were trained using a simpler version of the challenge. The authors posit that the training helped focus the females' attention on the spatial nature of the task, whereas males may be more naturally attuned to its spatial features.
"A few reports in humans suggest that men show greater age-related cognitive decline relative to women," Lacreuse remarks. "Our results in monkeys are consistent with these reports, at least concerning the specific domain of spatial cognition." Following the animals over longer time periods, she notes, will help identify potential links between age-related changes in variables such as hormones and changes in cognition. The findings appear in the February issue of Behavioral Neuroscience.