Structural racism influences environmental factors such as where people can live, the quality of schools in their communities, and exposure to harmful toxicants and pollutants. It also influences sociocultural factors such as access to quality health care, employment prospects, occupational safety, the ability to pass wealth to subsequent generations, treatment by the legal system and exposure to violence. Structural racism impacts many aspects of life that may directly or indirectly alter the ability to adhere to healthy behaviors or access resources that influence dementia risk. For example, some studies indicate that early life experiences with residential and school segregation can have detrimental effects on the cognitive health of Black Americans in later life.292-293 This points to a need for health disparities research that employs lifecourse perspectives to account for the many environmental and sociocultural factors that may put disproportionately affected populations at increased risk for Alzheimer’s and other dementias.288-289 There is evidence that missed diagnoses of Alzheimer’s and other dementias are more common among older Blacks and Hispanics than among older Whites.294-296 Based on data for Medicare beneficiaries age 65 and Research into biological sex differences has examined whether genetic risk operates differently in women and men or whether there are sex differences in the development of or susceptibility to Alzheimer’s pathology.261 A number of studies have shown that the APOE-e4 genotype, the best known genetic risk factor for Alzheimer’s dementia, may have a stronger association with Alzheimer’s dementia262-263 and neurodegeneration264 in women than in men. However, a recent meta-analysis found no difference between men and women in the association between APOE genotype and Alzheimer’s dementia overall, though there was an elevated risk for women with the APOE-e4 genotype at certain age ranges.265 It is unknown why the APOE gene could convey different risk for women, but some evidence suggests that it may be due to an interaction between the APOE genotype and the sex hormone estrogen.266-267 Finally, there is some evidence that women show more rapid cognitive decline and neurodegeneration than men despite having similar levels of beta-amyloid and tau, meaning the hallmark proteins of Alzheimer’s disease may have more negative effects for women than men.268-270 Racial and Ethnic Differences in the Prevalence of Alzheimer’s and Other Dementias Although there are more Whites living with Alzheimer’s and other dementias than any other racial or ethnic group in the United States (because Whites are the largest racial/ethnic group in the country), older Black and Hispanic Americans are disproportionately more likely than older White Americans to have Alzheimer’s or other dementias.271-277 Data from the CHAP study indicates 18.6% of Blacks and 14% of Hispanics age 65 and older have Alzheimer’s dementia compared with 10% of White older adults.216 Most other prevalence studies also indicate that older Blacks are about twice as likely to have Alzheimer’s or other dementias as older Whites.241,278-279 Some studies indicate older Hispanics are about one and one-half times as likely to have Alzheimer’s or other dementias as older Whites.279-281 However, Hispanics comprise very diverse groups with different cultural histories, genetic ancestries and health profiles, and there is evidence that prevalence may differ from one specific Hispanic ethnic group to another (for example, Mexican Americans compared with Caribbean Americans).282-283 The higher prevalence of Alzheimer’s dementia in underrepresented racial and ethnic groups compared with Whites appears to be due to a higher risk of developing dementia in these groups compared with whites of the same age.284 This higher risk, or incidence, of Alzheimer’s and other dementias appears to stem from variations in medical conditions, health-related Prevalence 26 Alzheimer’s Association. 2021 Alzheimer’s Disease Facts and Figures. Alzheimers Dement 2021;17(3). older, it has been estimated that Alzheimer’s or another dementia has been diagnosed in 10.3% of Whites, 12.2% of Hispanics and 13.8% of Blacks.297 Although rates of diagnosis were higher among Blacks and Hispanics than among Whites, according to prevalence studies that detect all people who have dementia irrespective of their use of health care systems, the rates should be even higher for Blacks and Hispanics. Data from population-based cohort studies regarding the national prevalence of Alzheimer’s and other dementias in racial and ethnic groups other than Whites, Blacks and Hispanics are relatively sparse. However, a study examining electronic medical records of members of a large health plan in California indicated that dementia incidence — determined by the first presence of a dementia diagnosis in members’ medical records — was highest for African Americans, intermediate for Latinos (the term used in the study for those who self-reported as Latino or Hispanic) and Whites, and lowest for Asian Americans.298 A follow-up study with the same cohort showed heterogeneity within AsianAmerican subgroups, but all subgroups studied had lower dementia incidence than Whites.299 A recent systematic review of the literature found that Japanese Americans were the only Asian American subgroup with reliable prevalence data, and that they had the lowest prevalence of dementia compared with all other ethnic groups.283 More studies, especially those involving populationbased cohorts, are necessary to draw conclusions about the prevalence of Alzheimer’s and other dementias in different racial groups and subgroups. Trends in the Prevalence and Incidence of Alzheimer’s Dementia Over Time A growing number of studies indicate that the prevalence219,256,300-307 and incidence251,303,307-315 of Alzheimer’s and other dementias in the United States and other higher income Western countries may have declined in the past 25 years,251,256,302-314 though results are mixed.64,241,316-317 One recent systematic review found that incidence of dementia has decreased over the last four decades while incidence of Alzheimer’s dementia, specifically, has held steady, but more research on this distinction is needed, especially in non-Western countries.318 Declines in dementia risk have been attributed to increasing levels of education and improved control of cardiovascular risk factors.