Sex-Specific Protective Effects of Cognitive Reserve on Age-Related Cognitive Decline
Jane Alty, Aidan Bindoff, Kimberley E. Stuart, Eddy Roccati, Jessica M. Collins, Anna E. King, Mathew J. Summers, James C. Vickers
Abstract
BACKGROUND AND OBJECTIVES: Females have a higher age-adjusted incidence of Alzheimer disease than males but the reasons for this remain unclear. One proposed contributing factor is that, historically, females had less access to education and, therefore, may accumulate less cognitive reserve. However, educational attainment is confounded by IQ, which in itself is a component of cognitive reserve and does not differ between sexes. Steeper age-related cognitive declines are associated with increased risk of dementia. We, therefore, evaluated the moderating effects of 2 proxies for cognitive reserve, education and IQ, on the steepness of age-related declining cognitive trajectories in unimpaired older males and females. METHODS: allelic variant on cognitive trajectories were compared between males and females. RESULTS: genotypes in either sex. DISCUSSION: IQ, a measure of cognitive reserve, predicted the steepness of declining cognitive trajectories in males only. Education did not explain as much variation in cognitive trajectories as IQ. Our findings do not support the hypothesis that historical sex disparities in access to education contribute to the higher female incidence of Alzheimer disease.