Lifetime Risk of Alzheimer’s Dementia Lifetime risk is the probability that someone of a given age who does not have a particular condition will develop the condition during his or her remaining life span. Data from the Framingham Heart Study were used to estimate lifetime risks of Alzheimer’s dementia by age and sex.A4,244 As shown in Figure 4, the study found that the estimated lifetime risk for Alzheimer’s dementia at age 45 was approximately 1 in 5 (20%) for women and 1 in 10 (10%) for men. The risks for both sexes were slightly higher at age 65.244 Differences Between Women and Men in the Prevalence and Risk of Alzheimer’s and Other Dementias More women than men have Alzheimer’s or other dementias. Almost two-thirds of Americans with Alzheimer’s are women.216 Of the 6.2 million people age 65 and older with Alzheimer’s in the United States, 3.8 million are women and 2.4 million are men.216 This represents 12% of women and 9% of men age 65 and older in the United States.213 The prevailing reason that there are more women living with Alzheimer’s or other dementias than men is most likely the fact that women live longer than men on average, and older age is the greatest risk factor for Alzheimer’s.244-246 However, when it comes to differences in the actual risk of developing Alzheimer’s or other dementias for men and women of the same age (i.e., incidence), findings have been mixed. Most studies of incidence in the United States have found no significant difference between men and women in the proportion who develop Alzheimer’s or other dementias at any given age.75,242,246-248 Some European studies have reported a higher incidence among women at older ages,249-250 and one study from the United Kingdom reported higher incidence for men.251 Differences in the risk of dementia between men and women may therefore depend on age and/or geographic region.252-253 Although there do not appear to be large or consistent differences in the rate at which men and women develop Alzheimer’s or other dementias, there may be differences in the reasons they develop dementia. These differences may be based in biology such as chromosomal or hormonal differences (i.e., sex differences) or differences in environmental, social and cultural influences on men and women (i.e., gender differences), or the combination of the two.252,254 There are many instances of gender difference in the distribution of or even the effect of known risk factors for dementia, such as education, occupation and health behaviors. For example, lower educational attainment in women than in men born in the first half of the 20th century could account for elevated risk in women, as limited formal education is a risk factor for dementia.255 This explanation requires more research, but there is evidence that increases in educational attainment over time in the United States — which have been more substantial for women than men — have led to decreased risk for dementia.256 Interestingly, European studies have found that the relationship of lower education with dementia outcomes may actually be stronger in women than men.257-258 Other societal gender differences may also be at play, such as differences in occupational attainment between men and women, with a recent study showing that women who participated in the paid workforce earlier in life had better cognitive outcomes after age 60.259-260 Other studies have provided evidence that any observed difference in risk for dementia between men and women may be an artifact of who is more or less likely to die of other health factors before developing dementia. A study using Framingham Heart Study data suggested that men in the study appear to have a lower risk for dementia due to “survival bias,” in which the men who survived beyond age 65 and were included in the study were the ones with a healthier cardiovascular risk profile (men have a higher rate of death from cardiovascular disease in middle age than women) and thus a lower risk for dementia.245 More research is needed to support this interpretation. Created from data from Chene et al.244 10.3% 19.5% 25 20 15 10 5 0 Age 45 65 11.6% 21.1% Percentage Men Women Estimated Lifetime Risk for Alzheimer’s Dementia, by Sex, at Ages 45 and 65 FIGURE 4 25 behaviors and socioeconomic risk factors across racial groups.277 Despite some evidence that the influence of genetic risk factors on Alzheimer’s and other dementias may differ by race,85,87,285 genetic factors do not account for the large differences in prevalence or incidence among racial groups.284,286 Instead, the difference in risk for Alzheimer’s and other dementias is explained by disparities in health conditions, socioeconomics, and life experiences for older Black and Hispanic populations compared with older White populations. Many studies suggest that racial and ethnic differences in dementia risk do not persist in rigorous analyses that account for health and socioeconomic factors.140,217,284 Chronic health conditions that are associated with higher dementia risk, such as cardiovascular disease and diabetes, disproportionately affect Black and Hispanic populations.287-288 Social and environmental disparities including lower levels and quality of education, higher rates of poverty, and greater exposure to adversity and discrimination increase risk for these chronic conditions and risk for dementia in Black and Hispanic populations.85,287-289 These health and socioeconomic disparities are rooted in the history of discrimination against Black and other people of color in the United States, not only during interpersonal interactions, but also as enshrined in the rules, practices and policies of U.S. banks, laws, medical systems and other institutions — that is, structural racism.