Heterogeneity in the effect of type 2 diabetes on dementia incidence in a diverse cohort of Asian American and non-Latino White older adults.

Dementia incidence is lower among Asian Americans than Whites, despite higher prevalence of type 2 diabetes, a well-known dementia risk factor. Determinants of dementia, including type 2 diabetes, have rarely been studied in Asian Americans. We followed 4,846 Chinese, 4,129 Filipino, 2,784 Japanese, 820 South Asian, and 123,360 non-Latino White members of a California-based integrated healthcare delivery system from 2002-2020. We estimated dementia incidence rates by race/ethnicity and type 2 diabetes status, and fit Cox proportional hazards and Aalen additive hazards models for the effect of type 2 diabetes (assessed 5 years before baseline) on age of dementia diagnosis controlling for sex/gender, educational attainment, nativity, height, race/ethnicity, and a race/ethnicity*diabetes interaction. Type 2 diabetes was associated with higher dementia incidence in Whites (hazard ratio [HR] 1.46, 95% confidence interval [CI] 1.40-1.52). Compared with Whites, the estimated effect of diabetes was larger in South Asians (2.26 [1.48-3.44]), slightly smaller in Chinese (1.32 [1.08-1.62]) and Filipino (1.31 [1.08-1.60]), and similar in Japanese (1.44 [1.15-1.81]) individuals. Heterogeneity in this association across Asian subgroups may be related to type 2 diabetes severity. Understanding this heterogeneity may inform prevention strategies to prevent dementia for all racial and ethnic groups.

How Generalizable Are Findings from a Community-Based Prospective Cohort Study? Extending Estimates from the Adult Changes in Thought Study to Its Source Population.

Background: The Adult Changes in Thought (ACT) study is a cohort of Kaiser Permanente Washington members ages 65+ that began in 1994. Objective: We wanted to know how well ACT participants represented all older adults in the region, and how well ACT findings on eye disease and its relationship with Alzheimer's disease generalized to all older adults in the Seattle Metropolitan Region. Methods: We used participation weights derived from pooling ACT and Behavioral Risk Factor Surveillance System (BRFSS) data to estimate prevalences of common eye diseases and their associations with Alzheimer's disease incidence. Cox proportional hazards models accounted for age, education, smoking, sex, and APOE genotype. Confidence intervals for weighted analyses were bootstrapped to account for error in estimating the weights. Results: ACT participants were fairly similar to older adults in the region. The largest differences were more self-reported current cholesterol medication use in BRFSS and higher proportions with low education in ACT. Incorporating the weights had little impact on prevalence estimates for age-related macular degeneration or glaucoma. Weighted estimates were slightly higher for diabetic retinopathy (weighted 5.7% (95% Confidence Interval 4.3, 7.1); unweighted 4.1% (3.6, 4.6)) and cataract history (weighted 51.8% (49.6, 54.3); unweighted 48.6% (47.3, 49.9)). The weighted hazard ratio for recent diabetic retinopathy diagnosis and Alzheimer's disease was 1.84 (0.34, 4.29), versus 1.32 (0.87, 2.00) in unweighted ACT. Conclusions: Most, but not all, associations were similar after participation weighting. Even in community-based cohorts, extending inferences to broader populations may benefit from evaluation with participation weights.

School racial composition, effect modification by caring teacher/staff presence, and mid/late-life depressive symptoms: findings from the Study of Healthy Aging among African Americans.

For Black students in the United States, attending schools with a higher proportion of White students is associated with worse mental and physical health outcomes in adolescence/early adulthood. No prior studies evaluate K-12 school racial composition and later-life mental health. In a cohort of Black adults ages 50+ in Northern California who retrospectively self-reported school racial composition for grades 1, 6, 9, and 12, we assessed the association between attending a school with mostly Black students vs. not and mid/late-life depressive symptoms (8-item PROMIS depression score, standardized to US adult population) using age-, sex/gender-, southern US birth-, and parental education-adjusted generalized estimating equations, and assessed effect modification by caring teacher/staff presence. Later-life depressive symptoms were lower among those who attended schools with mostly Black students in grades 1 and 6 (b=-0.12, 95% CI: -0.23, 0.00 and b=-0.11, 95% CI: -0.22, 0.00, respectively). In grade 6, this difference was larger for students without an adult at school who cared about them (b=-0.29, 95% CI: -0.51, -0.07 vs. b=-0.04, 95% CI: -0.17, 0.09). Among Black Americans, attending early school with mostly Black students may have later life mental health benefits; this protective association appears more important for students without caring teachers/staff.

Representativeness of samples enrolled in Alzheimer's disease research centers.

To generalize findings on the mechanisms and prognosis in Alzheimer's disease and related dementias (ADRD), it is critical for ADRD research to be representative of the population. Sociodemographic and health characteristics across ethnoracial groups included in the National Alzheimer's Coordinating Center sample (NACC) were compared to the nationally representative Health and Retirement Study (HRS).Baseline NACC data (n = 36,639) and the weighted 2010 HRS wave (N = 52,071,840) were included. We assessed covariate balance by calculating standardized mean differences across harmonized covariates (i.e., sociodemographic, health).NACC participants were older, more educated, with worse subjective memory and hearing, but endorsed fewer depressive symptoms compared to HRS participants. While all racial and ethnic groups in NACC differed from HRS participants in the same way overall, these differences were further amplified between racial and ethnic groups.NACC participants do not represent the U.S. population in key demographic and health factors, which differed by race and ethnicity. HIGHLIGHTS: We examined selection factors included in NACC studies compared to a nationally representative sample.Selection factors included demographic and health factors and self-reported memory concerns.Results suggest that NACC participants are not representative of the U.S. population.Importantly, selection factors differed across racial and ethnic groups.Findings are suggestive of selection bias within NACC studies.

Association of Education With Dementia Incidence Stratified by Ethnicity and Nativity in a Cohort of Older Asian American Individuals.

Importance: High education protects against dementia, but returns on educational attainment may be different across sociodemographic groups owing to various social factors. Asian American individuals are a growing and diverse group, but little research has assessed dementia determinants in this population. Objective: To examine the association of education with dementia in a large cohort of Asian American individuals, stratifying by ethnicity and nativity. Design, Setting, and Participants: This cohort study used electronic health record (EHR) and survey data from the Research Program on Genes, Environment, and Health and the California Men's Health Study surveys (2002-2020). Data are from Kaiser Permanente Northern California, an integrated health care delivery system. This study used a volunteer sample who completed the surveys. Participants included Chinese, Filipino, and Japanese individuals who were aged 60 to less than 90 years without a dementia diagnosis in the EHR at the time of the survey (baseline) and who had 2 years of health plan coverage before baseline. Data analysis was performed from December 2021 to December 2022. Exposures: The main exposure was educational attainment (college degree or higher vs less than a college degree), and the main stratification variables were Asian ethnicity and nativity (born in the US or born outside the US). Main Outcomes and Measures: The primary outcome was incident dementia diagnosis in the EHR. Dementia incidence rates were estimated by ethnicity and nativity, and Cox proportional hazards and Aalen additive hazards models were fitted for the association of college degree or higher vs less than a college degree with time to dementia, adjusting for age (timescale), sex, nativity, and an interaction between nativity and college degree. Results: Among 14 749 individuals, the mean (SD) age at baseline was 70.6 (7.3) years, 8174 (55.4%) were female, and 6931 (47.0%) had attained a college degree. Overall, among individuals born in the US, those with a college degree had 12% lower dementia incidence (HR, 0.88; 95% CI, 0.75-1.03) compared with those without at least a college degree, although the confidence interval included the null. The HR for individuals born outside the US was 0.82 (95% CI, 0.72-0.92; P = .46 for the college degree by nativity interaction). The findings were similar across ethnicity and nativity groups except for Japanese individuals born outside the US. Conclusions and Relevance: These findings suggest that college degree attainment was associated with lower dementia incidence, with similar associations across nativity. More work is needed to understand determinants of dementia in Asian American individuals and to elucidate mechanisms linking educational attainment and dementia.

The impact of attending historically Black colleges and universities on cognitive decline in Black adults: A longitudinal analysis in the KHANDLE and STAR cohorts.

INTRODUCTION: Black students attending predominantly White institutions (PWIs) versus historically Black colleges and universities (HBCUs) report more harmful discrimination and develop worse mental health outcomes, potentially offsetting the established benefits of college for lowering dementia incidence. METHODS: Black participants in two cohorts (the Kaiser Healthy Aging and Diverse Life Experiences [KHANDLE] and the Study of Healthy Aging in African Americans [STAR]) who had attended college (N = 716) self-reported the college name (classified as HBCU vs. PWI) and completed three waves of executive function (EF) and verbal episodic memory (VEM) assessments. HBCU effects on cognitive level and decline were estimated using adjusted linear mixed-effects models. RESULTS: HBCU (vs. PWI) attendees averaged better EF (ß = 0.05 [-0.22, 0.32]) and VEM (ß = 0.21 [-0.06, 0.46]) at age 70 though neither association was statistically significant. HBCU attendance was associated with slightly faster VEM decline (ß = -0.03 [-0.05, 0.00]). DISCUSSION: Harmonized analyses with larger studies are needed to estimate important effects of HBCU attendance. HIGHLIGHTS: Higher education is robustly linked to lower dementia risk, yet Black-White inequities persist among college-educated adults. Black students attending predominantly White institutions (PWIs) versus historically Black colleges and universities (HBCUs) report more harmful discrimination and develop worse mental health outcomes, which may offset the established benefits of college for lowering dementia incidence. HBCU (vs. non-HBCU) attendees averaged better executive function and verbal episodic memory (VEM) at average age 70, though confidence intervals were wide and associations were not statistically significant, and averaged slightly faster decline in VEM. Harmonized analyses using larger nationally representative studies are likely needed to avoid underestimating the health effects of HBCU attendance.

Neighborhood disadvantage and dementia incidence in a cohort of Asian American and non-Latino White older adults in Northern California.

INTRODUCTION: Some evidence suggests that neighborhood socioeconomic disadvantage is associated with dementia-related outcomes. However, prior research is predominantly among non-Latino Whites. METHODS: We evaluated the association between neighborhood disadvantage (Area Deprivation Index [ADI]) and dementia incidence in Asian American (n = 18,103) and non-Latino White (n = 149,385) members of a Northern California integrated health care delivery system aged 60 to 89 at baseline. Race/ethnicity-specific Cox proportional hazards models adjusted for individual-level age, sex, socioeconomic measures, and block group population density estimated hazard ratios (HRs) for dementia. RESULTS: Among non-Latino Whites, ADI was associated with dementia incidence (most vs. least disadvantaged ADI quintile HR = 1.09, 95% confidence interval [CI] = 1.02-1.15). Among Asian Americans, associations were close to null (e.g., most vs. least disadvantaged ADI quintile HR = 1.01, 95% CI = 0.85-1.21). DISCUSSION: ADI was associated with dementia incidence among non-Latino Whites but not Asian Americans. Understanding the potentially different mechanisms driving dementia incidence in these groups could inform dementia prevention efforts.

Accounting for lack of representation in dementia research: Generalizing KHANDLE study findings on the prevalence of cognitive impairment to the California older population.

INTRODUCTION: Most dementia studies are not population-representative; statistical tools can be applied to samples to obtain critically-needed population-representative estimates, but are not yet widely used. METHODS: We pooled data from the Kaiser Healthy Aging and Diverse Life Experiences (KHANDLE) study and the California Behavioral Risk Factor Surveillance System (CA-BRFSS), a population-representative study. Using weights accounting for sociodemographic/health differences between KHANDLE and CA-BRFSS, we estimated cognitive impairment prevalence and age- and sex-adjusted racial/ethnic inequalities in California adults 65+ without prior dementia diagnosis. RESULTS: After weighting KHANDLE, the estimated cognitive impairment prevalence in California was 20.3% (95% confidence interval 17.8-23.0); unweighted prevalence was 24.8% (23.1%-26.6%). Inequalities (larger prevalences) were observed among Black and Asian groups versus whites. DISCUSSION: We used a novel statistical approach to estimate population-representative cognitive impairment prevalence and inequalities. Such statistical tools can help obtain population-representative estimates from existing studies and inform efforts to reduce racial/ethnic disparities.

The role of nativity in heterogeneous dementia incidence in a large cohort of three Asian American groups and white older adults in California.

INTRODUCTION: Literature shows lower dementia incidence in Asian American groups versus whites, varying by Asian ethnicity. One hypothesized driver is nativity differences (eg, healthy immigrant effect). METHODS: We followed a cohort of 6243 Chinese, 4879 Filipino, 3256 Japanese, and 141,158 white Kaiser Permanente Northern California members for incident dementia (2002 to 2020), estimating age-adjusted dementia incidence rates by ethnicity and nativity, and hazard ratios (HR) for nativity on dementia incidence using ethnicity-stratified age- and sex-adjusted Cox proportional hazards models. RESULTS: Dementia incidence appeared higher in foreign- versus US-born Filipinos (HR, 95% confidence interval: 1.39, 1.02 to 1.89); differences were small in Japanese (1.07, 0.88 to 1.30) and Chinese (1.07, 0.92 to 1.24). No nativity differences were observed among whites (1.00, 0.95 to 1.04). DISCUSSION: Nativity does not explain lower dementia incidence in Asian Americans versus whites, but may contribute to heterogeneity across Asian ethnicities. Future research should explore differential impacts of social and cardiometabolic factors.

Racial/Ethnic Differences in Health-Related Quality of Life in Persons With and Without Dementia.

BACKGROUND/OBJECTIVES: Given the lack of effective pharmacologic strategies to prevent, slow, or reverse dementia progression, maximizing quality of life (QOL) is a major priority for persons living with dementia. Despite well-documented racial/ethnic disparities in dementia incidence and prevalence, it is unknown whether there are racial/ethnic disparities in QOL among persons with dementia. The objective of this study was to determine if there are racial/ethnic differences in poor health-related quality of life (HRQOL) among persons with and without dementia in a nationally-representative cohort. DESIGN: Repeated measures cross-sectional analysis of a prospective cohort study. SETTING: United States nationally-representative National Health and Aging Trends Study (2011-2018). PARTICIPANTS: Non-nursing home-dwelling Black, Latino, and white adults age 65+ (n = 10,886). MEASUREMENTS: We estimated racial/ethnic differences in five dichotomous indicators of poor HRQOL (depressive and anxiety symptoms, self-rated health, pain, and physical functional limitations), stratified by dementia status (probable, possible, none). We used generalized estimating equations to estimate prevalence ratios (PRs) and differences, and marginal standardization to estimate prevalence. RESULTS: Generally, Blacks and Latinos reported higher prevalence of poor HRQOL compared with whites. The largest differences were observed for self-rated health, and Latino-white differences were slightly larger compared to Black-white differences. PRs were larger among those with no dementia. For example, the Black versus white PRs for poor self-rated health were 1.93 (95% confidence interval (CI) = 1.82-2.04) among the no dementia group and 1.21 (95% CI = 1.12-1.31) among the probable dementia group; Latino versus white PRs for these comparisons were 2.39 (2.21-2.59) and 1.48 (1.35-1.62), respectively. Prevalence differences also showed racial/ethnic differences, but these were similar across dementia statuses. CONCLUSIONS: We observed racial/ethnic disparities in poor HRQOL, showing greater unmet clinical needs among Black and Latino versus white older adults. Relative disparities were smaller in those with dementia, but absolute magnitudes of disparities were similar by dementia status.

Association of work-family experience with mid- and late-life memory decline in US women.

OBJECTIVE: To test the hypothesis that life course patterns of employment, marriage, and childrearing influence later-life rate of memory decline among women, we examined the relationship of work-family experiences between ages 16 and 50 years and memory decline after age 55 years among US women. METHODS: Participants were women ages ≥55 years in the Health and Retirement Study. Participants reported employment, marital, and parenthood statuses between ages 16 and 50 years. Sequence analysis was used to group women with similar work-family life histories; we identified 5 profiles characterized by similar timing and transitions of combined work, marital, and parenthood statuses. Memory performance was assessed biennially from 1995 to 2016. We estimated associations between work-family profiles and later-life memory decline with linear mixed-effects models adjusted for practice effects, baseline age, race/ethnicity, birth region, childhood socioeconomic status, and educational attainment. RESULTS: There were 6,189 study participants (n = 488 working nonmothers, n = 4,326 working married mothers, n = 530 working single mothers, n = 319 nonworking single mothers, n = 526 nonworking married mothers). Mean baseline age was 57.2 years; average follow-up was 12.3 years. Between ages 55 and 60, memory scores were similar across work-family profiles. After age 60, average rate of memory decline was more than 50% greater among women whose work-family profiles did not include working for pay after childbearing, compared with those who were working mothers. CONCLUSIONS: Women who worked for pay in early adulthood and midlife experienced slower rates of later-life memory decline, regardless of marital and parenthood status, suggesting participation in the paid labor force may protect against later-life memory decline.