Are sex differences in verbal memory related to sex differences in cognitive reserve?

Abstract

AbstractBackgroundCognitive reserve (CR) is the capacity to maintain cognitive performances despite underlying brain pathology and a concept used in Alzheimer’s disease (AD) studies to explain clinical heterogeneity. Evidence for a female‐specific verbal memory reserve may contribute to sex disparities in AD incidence, via delayed diagnosis. However, whether sex differences in verbal memory relate to sex differences in CR, is unclear. The current study examined whether multiple measures of CR differed by sex and whether they mediated sex differences in verbal memory.MethodCross‐sectional data from 59 older adults (mean age = 68.1; SD = 10.7; Female = 62%; White = 70%), without a prior diagnosis of cognitive impairment, were included. Total recall from the immediate and delayed recall trials of the scores Hopkins Verbal Learning Test (HVLT) were used to assess verbal learning and memory. Years of education, self‐reported leisure activities, physical activity, mindfulness, and the MIND diet were used to assess CR. Sex differences in HVLT scores were tested with ANCOVAs, controlling for age and reran adjusting for education. A MANCOVA was used to assess sex differences on CR measures. A mediation analyses was used to test whether sex differences in CR measures mediated the association between sex differences and verbal memory.ResultWomen had higher scores on HVLT learning (M = 23.1, SD = 5.2; p<.01), delayed recall (M = 8.2; SD = 2.6; p<.01) and leisure activities (M = 35.93; SD = 7.9; p<.01) compared to men (learning: M = 19.5; SD = 5.2; delayed recall: M = 6.2; SD = 2.5; leisure: M = 28.5; SD = 10.9; p<.01). No other sex differences in CR measures were revealed. Leisure activities fully mediated sex and HVLT associations, such that women’s higher scores on leisure explained 39% and 35% of the variance between sex and HVLT learning and delayed recall, respectively.ConclusionWomen’s overall higher engagement in leisure activities accounted for their higher scores on HVLT learning and delayed recall relative to men. Increasing men’s engagement in leisure activities could attenuate sex differences in verbal learning/memory but warrants further investigation. Larger and more diverse samples are needed for follow‐up data analyses.