Trends in memory function and memory impairment among older adults in the USA and Europe, 1996-2018.

BACKGROUND: Single-country studies document varying time trends in memory function and impairment. Comparative analyses are limited. METHODS: We used self-respondent data on adults aged 50+ years in 13 countries from three surveys (USA: HRS, 1998-2018; England: ELSA, 2002-2018; 11 European countries: SHARE, 2004-2019). Memory is measured with tests of immediate and delayed word recall. Unweighted age- and gender-adjusted mixed effects regression models as well as models with adjustments for additional socio-demographic characteristics and health behaviors were examined. Heterogeneity in trends by gender, age group, and educational attainment were measured. RESULTS: The age-adjusted 10-year improvement in average test score is 0.04 standard deviations (SDs) (95% confidence interval (CI): 0.03, 0.05) in the USA, 0.17 SDs (95% CI: 0.15, 0.19) in England, and 0.24 SDs (95% CI: 0.23, 0.25) in SHARE countries. Trends are largely similar across gender, age groups, and educational attainment. Regional differences in trends remain after adjustment for potential mechanisms. Difference between the USA and other countries is particularly large under aged 75 years compared to over aged 75 years. CONCLUSIONS: Pace of improvement in memory function varies strongly across countries. On average, the 11 European countries studied had the fastest improvement, followed by England. The trend in the USA indicates improvement, but at a much slower pace compared to that in England and other European countries. Uncovering the causes for the cross-country heterogeneity in time trends, and in particular the reasons for the comparatively poor performance of the USA, should be both a research and public health priority.

Cognitive impairment and partnership status in the United States, 1998-2016, by sex, race/ethnicity, and education.

Cognitively impaired adults without a partner are highly disadvantaged, as partners constitute an important source of caregiving and emotional support. With the application of innovative multistate models to the Health and Retirement Study, this paper is the first to estimate joint expectancies of cognitive and partnership status at age 50 by sex, race/ethnicity, and education in the United States. We find that women live a decade longer unpartnered than men. Women are also disadvantaged as they experience three more years as both cognitively impaired and unpartnered than men. Black women live over twice as long as cognitively impaired and unpartnered compared with White women. Lower-educated men and women live around three and five years longer, respectively, as cognitively impaired and unpartnered than more highly educated men and women. This study addresses a novel facet of partnership and cognitive status dynamics and examines their variations by key socio-demographic factors.

Racial, Ethnic, Nativity, and Educational Disparities in Cognitive Impairment and Activity Limitations in the United States, 1998-2016.

Despite extensive research on cognitive impairment and limitations in basic activities of daily living, no study has investigated the burden of their co-occurrence (co-impairment). Using the Health and Retirement Study data and incidence-based multistate models, we study the population burden of co-impairment using three key indicators: mean age at onset, lifetime risk, and health expectancy. We examine patterns by gender, race, ethnicity, nativity, education, and their interactions for U.S. residents aged 50-100. Furthermore, we analyze what fractions of racial, ethnic, and nativity disparities in co-impairment are attributable to inequalities in educational attainment. Results reveal that an estimated 56% of women and 41% of men aged 50 will experience co-impairment in their remaining life expectancy. Men experience an earlier onset of co-impairment than women (74 vs. 77 years), and women live longer in co-impairment than men (3.4 vs. 1.9 years). Individuals who are Black, Latinx, and lower educated, especially those experiencing intersecting disadvantages, have substantially higher lifetime risk of co-impairment, earlier co-impairment onset, and longer life in co-impairment than their counterparts. Up to 75% of racial, ethnic, and nativity disparity is attributable to inequality in educational attainment. This study provides novel insights into the burden of co-impairment and offers evidence of dramatic disparities in the older U.S. population.

A Longitudinal Analysis of the Association Between Long-Term Exposure to Air Pollution and Cognitive Function Among Adults Aged 45 and Older in China.

OBJECTIVES: Evidence suggests long-term exposure to fine particulate matter air pollution (PM2.5) is associated with a higher risk of cognitive impairment, especially among older adults. This study examines the relationship between PM2.5 exposure and cognitive function in China's aging population. METHODS: We used longitudinal data from the China Health and Retirement Longitudinal Study (2011-2015) linked with historical PM2.5 concentrations (2000-2015) from remotely sensed satellite data. Growth curve models were applied to estimate associations between PM2.5 exposure (measured in intensity, duration, and a joint variable of intensity with duration for cumulative exposure) and cognitive function. RESULTS: Relative to the lowest exposure group, exposure in the second group of PM2.5 intensity (35-50 µg/m3) is associated with poorer cognitive function, but higher levels of PM2.5 appear to be associated with better cognitive function, indicating a U-shaped association. Similar patterns are seen for fully adjusted models of PM2.5 duration: the second group (13-60 months) is associated with worse cognitive function than the first group (0-12 months), but coefficients are nonsignificant in longer duration groups. Joint analysis of PM2.5 intensity with duration suggests that duration may play a more detrimental role in cognitive function than intensity. However, we do not find a statistically significant association between PM2.5 exposure and the rate of cognitive decline. DISCUSSION: Our findings are mixed and suggest that some categories of higher and longer exposure to PM2.5 are associated with poorer cognitive function, while that exposures do not hasten cognitive decline. However, more work is necessary to disentangle PM2.5 exposure from individuals' background characteristics, particularly those jointly associated with cognitive function and urban living.

A longitudinal analysis of PM2.5 exposure and multimorbidity clusters and accumulation among adults aged 45-85 in China.

While previous studies have emphasised the role of individual factors in understanding multimorbidity disparities, few have investigated contextual factors such as air pollution (AP). We first use cross-sectional latent class analysis (LCA) to assess the associations between PM2.5 exposure and multimorbidity disease clusters, and then estimate the associations between PM2.5 exposure and the development of multimorbidity longitudinally using growth curve modelling (GCM) among adults aged 45-85 in China. The results of LCA modelling suggest four latent classes representing three multimorbidity patterns (respiratory, musculoskeletal, cardio-metabolic) and one healthy pattern. The analysis shows that a 1 µg/m3 increase in cumulative exposure to PM2.5 is associated with a higher likelihood of belonging to respiratory, musculoskeletal or cardio-metabolic clusters: 2.4% (95% CI: 1.02, 1.03), 1.5% (95% CI: 1.01, 1.02) and 3.3% (95% CI: 1.03, 1.04), respectively. The GCM models show that there is a u-shaped association between PM2.5 exposure and multimorbidity, indicating that both lower and higher PM2.5 exposure is associated with increased multimorbidity levels. Higher multimorbidity in areas of low AP is explained by clustering of musculoskeletal diseases, whereas higher AP is associated with cardio-metabolic disease clusters. The study shows how multimorbidity clusters vary contextually and that PM2.5 exposure is more detrimental to health among older adults.

Does postponing retirement affect cognitive function? A counterfactual experiment to disentangle life course risk factors.

Evidence suggests that contemporaneous labor force participation affects cognitive function; however, it is unclear whether it is employment itself or endogenous factors related to individuals' likelihood of employment that protects against cognitive decline. We exploit innovations in counterfactual causal inference to disentangle the effect of postponing retirement on later-life cognitive function from the effects of other life-course factors. With the U.S. Health and Retirement Study (1996-2014, n = 20,469), we use the parametric g-formula to estimate the effect of postponing retirement to age 67. We also study whether the benefit of postponing retirement is affected by gender, education, and/or occupation, and whether retirement affects cognitive function through depressive symptoms or comorbidities. We find that postponing retirement is protective against cognitive decline, accounting for other life-course factors (population: 0.34, 95% confidence interval (CI): 0.20,0.47; individual: 0.43, 95% CI: 0.26,0.60). The extent of the protective effect depends on subgroup, with the highest educated experiencing the greatest mitigation of cognitive decline (individual: 50%, 95% CI: 32%,71%). By using innovative models that better reflect the empirical reality of interconnected life-course processes, this work makes progress in understanding how retirement affects cognitive function.

Working and disability expectancies at older ages: The role of childhood circumstances and education.

The ability to work at older ages depends on health and education. Both accumulate starting very early in life. We assess how childhood disadvantages combine with education to affect working and health trajectories. Applying multistate period life tables to data from the Health and Retirement Study (HRS) for the period 2008-2014, we estimate how the residual life expectancy at age 50 is distributed in number of years of work and disability, by number of childhood disadvantages, gender, and race/ethnicity. Our findings indicate that number of childhood disadvantages is negatively associated with work and positively with disability, irrespective of gender and race/ethnicity. Childhood disadvantages intersect with low education resulting in shorter lives, and redistributing life years from work to disability. Among the highly educated, health and work differences between groups of childhood disadvantage are small. Combining multistate models and inverse probability weighting, we show that the return of high education is greater among the most disadvantaged.

The association between city-level air pollution and frailty among the elderly population in China.

A growing body of research suggests that air pollution negatively affects specific health outcomes, but how long- and short-term exposure to air pollution are associated with frailty is unclear. Using longitudinal data from adults aged 65 and over from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) linked with air quality index data, we model a frailty score according to the city-level of air pollution exposure, adjusting for individual socio-demographic factors and city-level indicators. All models show increased frailty with higher exposure to air pollution in one year prior to the interview, when controlling for short-term fluctuations. Moreover, elderly people living in areas where air pollution increased over the follow-up had larger increases in frailty scores than those where air pollution was relatively constant. The results suggest that air pollution plays a role in healthy ageing.

Trends in the Risk of Cognitive Impairment in the United States, 1996-2014.

BACKGROUND: Accumulating evidence suggests risk of cognitive impairment is declining in high-income countries. Much of this research uses longitudinal surveys in which learning over repeated tests may bias results. We analyze trends in cognitive impairment in the United States, accounting for prior test experience and selective mortality. METHODS: We use the Health and Retirement Study, a population-based, nationally representative panel dataset and include individuals ages 50 years and older in 1996-2014 (n = 32,784). We measure cognitive impairment and dementia using standard cutpoints of the modified Telephone Interview for Cognitive Status. We estimate logistic regression models for any impairment and dementia over time, adjusting for age, sex, and race/ethnicity, comparing models with and without adjustment for practice effects and education. We examine heterogeneity in trends by age, sex, race/ethnicity, and education. RESULTS: Models not controlling for test experience suggest that risk of cognitive impairment and dementia decreased over the study period. Controlling for test experience reverses the trend. In our primary models, prevalence of any cognitive impairment increased for women from 18.7% to 21.2% (annual change 0.7%, 95% confidence interval [CI], 0.1%, 1.3%) and for men from 17.6% to 21.0% (annual change 1.0%, CI, 0.5%, 1.4%). For dementia, women's annual increase was 1.7% (CI, 0.8%, 2.6%) and men's 2.0% (CI, 1.0%, 2.9%). If not for education, the increase would have been stronger. Increased risk was particularly rapid for Latinas, the least educated, and older ages. CONCLUSIONS: Risk of cognitive impairment increased from 1996 to 2014. Uncovering determinants of increasing cognitive impairment risk should become a research priority. See video abstract: http://links.lww.com/EDE/B702.

Cognitive impairment in the U.S.: Lifetime risk, age at onset, and years impaired.

Prior studies have analyzed the burden of cognitive impairment, but often use potentially biased prevalence-based methods or measure only years lived with impairment, without estimating other relevant metrics. We use the Health and Retirement Study (1998-2014; n = 29,304) and the preferred incidence-based Markov-chain models to assess three key measures of the burden of cognitive impairment: lifetime risk, mean age at onset, and number of years lived impaired. We analyze both mild and severe cognitive impairment (dementia) and gender, racial/ethnic, and educational variation in impairment. Our results paint a multi-dimensional picture of cognitive health, presenting the first comprehensive analysis of the burden of cognitive impairment for the U.S. population age 50 and older. Approximately two out of three Americans experience some level of cognitive impairment at an average age of approximately 70 years. For dementia, lifetime risk for women (men) is 37% (24%) and mean age at onset 83 (79) years. Women can expect to live 4.2 years with mild impairment and 3.2 with dementia, men 3.5 and 1.8 years. A critical finding is that for the most advantaged groups (i.e., White and/or higher educated), cognitive impairment is both delayed and compressed toward the very end of life. In contrast, despite the shorter lives of disadvantaged subgroups (Black and/or lower educated), they experience a younger age of onset, higher lifetime risk, and more years cognitively impaired. For example, men with at least an Associate degree have 21% lifetime dementia risk, compared to 35% among men with less than high school education. White women have 6 years of cognitively-impaired life expectancy, compared to 12 and 13 years among Black women and Latinas. These educational and racial/ethnic gradients highlight the very uneven burden of cognitive impairment. Further research is required to identify the mechanisms driving these disparities in cognitive impairment.

Immigrant Legal Status and Health: Legal Status Disparities in Chronic Conditions and Musculoskeletal Pain Among Mexican-Born Farm Workers in the United States.

Immigrant legal status determines access to the rights and privileges of U.S. society. Legal status may be conceived of as a fundamental cause of health, producing a health disparity whereby unauthorized immigrants are disadvantaged relative to authorized immigrants, a perspective that is supported by research on legal status disparities in self-rated health and mental health. We conducted a systematic review of the literature on legal status disparities in physical health and examined whether a legal status disparity exists in chronic conditions and musculoskeletal pain among 17,462 Mexican-born immigrants employed as farm workers in the United States and surveyed in the National Agricultural Workers Survey between 2000 and 2015. We found that unauthorized, Mexican-born farm workers have a lower incidence of chronic conditions and lower prevalence of pain compared with authorized farm workers. Furthermore, we found a legal status gradient in health whereby naturalized U.S. citizens report the worst health, followed by legal permanent residents and unauthorized immigrants. Although inconsistent with fundamental cause theory, our results were robust to alternative specifications and consistent with a small body of existing research on legal status disparities in physical health. Although it is well known that Mexican immigrants have better-than-expected health outcomes given their social disadvantage, we suggest that an epidemiologic paradox may also apply to within-immigrant disparities by legal status. We offer several explanations for the counterintuitive result.

Trends in Hospital Deaths in Denmark from 1980 to 2014, at Ages 50 and Older.

OBJECTIVES: To explore temporal trends and individual-level determinants of hospital deaths at ages 50 and older in Denmark from 1980 to 2014. DESIGN: Individual-level register-based retrospective study. SETTING: Denmark, 1980 to 2014. PARTICIPANTS: All deaths that occurred in Denmark from 1980 to 2014 among individuals 50 years or older (N = 1 834 437), extracted from population registers. MEASUREMENTS: A death was defined as a hospital death if the individual was admitted to the hospital as an inpatient and the date of discharge from the hospital is equal to the date of death. RESULTS: The percentage of hospital deaths decreased in both sexes (all ages combined, men: 56% to 44%; women: 49% to 39%) and at ages 50 to 79, remained almost unchanged at ages 80 to 89, and increased in the oldest age group (90+ men: 27% to 32%; women: 18% to 24%). We observed increasing trends of hospital deaths for three groups, people 90 years and older, dying from respiratory diseases, and who had terminal hospitalizations lasting 1 to 3 days. Subanalysis of all hospital deaths according to length of the terminal hospitalizations suggests that the overall reduction of hospital deaths might be driven by a reduction in hospitalizations that were longer than 1 week. Persons who are married, have middle or high income, have a history of hospitalizations in the year before death, or die because of respiratory diseases have higher odds of dying in a hospital. CONCLUSION: Results provide evidence that Danes 50 years and older are increasingly dying outside the hospital context. We find three age-specific patterns in the proportion of hospital deaths. Changes in healthcare and social systems implemented in Denmark during the observation period may underlie the broader reduction in hospital deaths in the country. J Am Geriatr Soc 67:471-476, 2019.

Cognitive Disparities: The Impact of the Great Depression and Cumulative Inequality on Later-Life Cognitive Function.

Population aging has driven a spate of recent research on later-life cognitive function. Greater longevity increases the lifetime risk of memory diseases that compromise the cognitive abilities vital to well-being. Alzheimer's disease, thought to be the most common underlying pathology for elders' cognitive dysfunction (Willis and Hakim 2013), is already the sixth leading cause of death in the United States (Alzheimer's Association 2016). Understanding social determinants of pathological cognitive decline is key to crafting interventions, but evidence is inconclusive for how social factors interact over the life course to affect cognitive function. I study whether early-life exposure to the Great Depression is directly associated with later-life cognitive function, influences risky behaviors over the life course, and/or accumulates with other life-course disadvantages. Using growth curve models to analyze the Health and Retirement Study, I find that early-life exposure to the Great Depression is associated with fluid cognition, controlling for intervening factors-evidence for a critical period model. I find little support for a social trajectory model. Disadvantage accumulates over the life course to predict worse cognitive function, providing strong evidence for a cumulative inequality model.

Changes in the Transnational Family Structures of Mexican Farm Workers in the Era of Border Militarization.

Historically, undocumented Mexican farm workers migrated circularly, leaving family behind in Mexico on short trips to the United States. Scholars have argued that border militarization has disrupted circular migration as the costs of crossing the border lead to longer stays, increased settlement, and changing transnational family practices. Yet, no study has explored changes in the transnational family structures of Mexico-U.S. migrants that span the era of border militarization. Using data from the National Agricultural Workers Survey, we document a dramatic shift away from transnational family life (as measured by location of residence of dependent children) among undocumented Mexican farm workers and a less dramatic shift among documented Mexican farm workers in the United States between 1993 and 2012. These trends are not explained by changes in the sociodemographic characteristics of farm workers or by changing demographic conditions or rising violence in Mexico. One-half of the trend can be accounted for by lengthened duration of stay and increased connections to the United States among the undocumented, but none of the trend is explained by these measures of settlement among the documented, suggesting that some Mexican farm workers adopt new family migration strategies at first migration. Increases in border control are associated with lower likelihood that children reside in Mexico-a finding that holds up to instrumental variable techniques. Our findings confirm the argument that U.S. border militarization-a policy designed to deter undocumented migration-is instead disrupting transnational family life between Mexico and the United States and, in doing so, is creating a permanent population of undocumented migrants and their children in the United States.