Abstract
Sex differences in dementia risk are unclear, but some studies have found greater risk for women. To determine associations between sex and cognitive decline in order to better understand sex differences in dementia risk. This cohort study used pooled analysis of individual participant data from 5 cohort studies for years 1971 to 2017: Atherosclerosis Risk in Communities Study, Coronary Artery Risk Development in Young Adults Study, Cardiovascular Health Study, Framingham Offspring Study, and Northern Manhattan Study. Linear mixed-effects models were used to estimate changes in each continuous cognitive outcome over time by sex. Data analysis was completed from March 2019 to October 2020. Sex. The primary outcome was change in global cognition. Secondary outcomes were change in memory and executive function. Outcomes were standardized as t scores (mean [SD], 50 [10]); a 1-point difference represents a 0.1-SD difference in cognition. Among 34 349 participants, 26 088 who self-reported Black or White race, were free of stroke and dementia, and had covariate data at or before the first cognitive assessment were included for analysis. Median (interquartile range) follow-up was 7.9 (5.3-20.5) years. There were 11 775 (44.7%) men (median [interquartile range] age, 58 [51-66] years at first cognitive assessment; 2229 [18.9%] Black) and 14 313 women (median [interquartile range] age, 58 [51-67] years at first cognitive assessment; 3636 [25.4%] Black). Women had significantly higher baseline performance than men in global cognition (2.20 points higher; 95% CI, 2.04 to 2.35 points; P < .001), executive function (2.13 points higher; 95% CI, 1.98 to 2.29 points; P < .001), and memory (1.89 points higher; 95% CI, 1.72 to 2.06 points; P < .001). Compared with men, women had significantly faster declines in global cognition (-0.07 points/y faster; 95% CI, -0.08 to -0.05 points/y; P < .001) and executive function (-0.06 points/y faster; 95% CI, -0.07 to -0.05 points/y; P < .001). Men and women had similar declines in memory (-0.004 points/y faster; 95% CI, -0.023 to 0.014; P = .61). The results of this cohort study suggest that women may have greater cognitive reserve but faster cognitive decline than men, which could contribute to sex differences in late-life dementia.
Highlights
Sex differences in dementia risk are unclear
Women had significantly higher baseline performance than men in global cognition (2.20 points higher; 95% CI, 2.04 to 2.35 points; P < .001), executive function (2.13 points higher; 95% CI, 1.98 to 2.29 points; P < .001), and memory (1.89 points higher; 95% CI, 1.72 to 2.06 points; P < .001)
The results of this cohort study suggest that women may have greater cognitive reserve but faster cognitive decline than men, which could contribute to sex differences in late-life dementia
Summary
Sex differences in dementia risk are unclear. It is known that women have a greater prevalence of Alzheimer disease (AD) than men, at least partly because women live longer.[1,2,3] Some, but not all, studies suggest that women have higher incidence of AD.[4,5,6] Sex differences in biological factors (eg, sex hormones), health factors (eg, cardiovascular risk), and social factors (eg, education levels) are hypothesized to contribute to sex differences in dementia risk.[7,8] most studies have focused on the effects of cardiovascular risk and education on sex disparities in late-life dementia.[9,10] Whether cognitive trajectories differ by sex after accounting for sex differences in cardiovascular risk and education levels is unknown. Using a pooled cohort[11] of 5 diverse, well-characterized, population-based cohort studies with repeated objective measures of cognition, we conducted a study to assess sex differences in later-life cognitive trajectories. We hypothesized that women have greater cognitive decline than men after adjusting for potential confounders
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