detrimental effects on the cognitive health of Black Americans in later life.309-311 This points to a need for health disparities research that employs life course perspectives and the insights of race equity scholars to account for the many environmental and sociopolitical factors that may put disproportionately affected populations at increased risk for Alzheimer’s and other dementias.306,313 There is evidence that missed or delayed diagnoses of Alzheimer’s and other dementias are more common among Black and Hispanic older adults than among White older adults.238,240,314-315 Based on data from Medicare beneficiaries age 65 and older, it has been estimated that Alzheimer’s or another dementia has been diagnosed in 10.3% of White older adults, 12.2% of Hispanic older Prevalence 27 adults and 13.8% of Black older adults.316 Although these percentages indicate that the dementia burden is greater among Black and Hispanic older adults than among White older adults, according to prevalence studies that detect all people who have dementia irrespective of their use of health care systems, the percentages should be even higher for Black and Hispanic older adults. Population-based cohort studies regarding the national prevalence of Alzheimer’s and other dementias in racial and ethnic groups other than White, Black and Hispanic populations 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 American older adults; intermediate for Latino older adults (the term used in the study for those who self-reported as Latino or Hispanic), American Indian and Native Alaskan older adults, Pacific Islander older adults, and White older adults; and lowest for Asian American older adults.317 A follow-up study with the same cohort showed heterogeneity within Asian-American subgroups, but all subgroups studied had lower dementia incidence than the White population.318 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.302 We have limited understanding of Alzheimer’s disease as experienced by people of Middle Eastern and North African descent,319 those who identify with more than one race/ethnicity, and subgroups of origin within racial/ethnic groups.316 More studies, especially those involving community-based cohorts and those that focus on racial/ethnic groups historically not included in Alzheimer’s research, 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 prevalence223,267,315-322 and incidence270,320-329 of Alzheimer’s and other dementias in the United States and other higher income Western countries may have declined in the past 25 years,270,277,320-328,330-333 though results are mixed.60,261,334-335 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.336 Declines in dementia risk have been attributed to increasing levels of education and improved control of cardiovascular risk factors.277,323,326,330,337-338 Such findings are promising and suggest that identifying and reducing risk factors for dementia may be effective. Although these findings indicate that a person’s risk of dementia at any given age may be decreasing slightly, the total number of people with Alzheimer’s or other dementias in the United States and other high-income Western countries is expected to continue to increase dramatically because of the increase in the number of people at the oldest ages. It is unclear whether these encouraging trends will continue into the future given worldwide increases in diabetes and obesity among persons under 65 years old — potential risk factors for Alzheimer’s dementia — which may lead to a rebound in dementia risk in coming years.113,321,339-342 It is also not clear that these positive trends pertain to all racial and ethnic groups.261,292,337-338,343-344 Thus, while recent findings are promising, the social and economic burden of Alzheimer’s and other dementias will continue to grow. Moreover, 68% of the projected increase in the global prevalence and burden of dementia by 2050 will take place in low- and middle-income countries, where current evidence does not support a decline in the risk of Alzheimer’s and other dementias.345 It is not known how the prevalence of Alzheimer’s dementia in low- and middle-income countries will be affected by the neurologic effects of COVID-19,346 along with the pandemic’s disruptions to general and brain-related health care. Looking to the Future Continued Population Aging In 2011, the largest ever demographic generation of the American population — the baby boom generation — started