Racial Disparities in COVID-19 Experiences Among Older Adults With Disabling Conditions

OBJECTIVES

This paper examines the health, work, and financial experiences of older adults with disabling conditions during the COVID-19 pandemic. It also explores the role of county- and state-level conditions in these experiences.

METHODS

Using data from the 2020 Health and Retirement Study, we estimated regression models to assess differences in outcomes between those with and without disabling conditions and by race/ethnicity. We used multilevel modeling to assess whether and how county or state factors might be associated with the differences in these effects.

RESULTS

Older adults with disabilities were more likely to report experiencing financial hardships, delaying health care, and experiencing effects on work than those without disabilities; these differences are heighted between race and ethnicity. Older adults with disabilities were more likely to live in counties with greater social vulnerability.

DISCUSSION

This work underscores the importance of developing a robust, disability-inclusive public health response that protects older adults.

Effects of early-life environment and adulthood SES on cognitive change in a multiethnic cohort

OBJECTIVES

Early-life socioeconomic status (SES) and adversity are associated with late-life cognition and risk of dementia. We examined the association between early-life SES and adversity and late-life cross-sectional cognitive outcomes as well as global cognitive decline, hypothesizing that adulthood SES would mediate these associations.

METHODS

Our sample (N = 837) was a racially and ethnically diverse cohort of non-Hispanic/Latino White (48%), Black (27%), and Hispanic/Latino (19%) participants from Northern California. Participant addresses were geocoded to the level of the census tract, and US Census Tract 2010 variables (e.g., percent with high school diploma) were extracted and combined to create a neighborhood SES composite. We used multilevel latent variable models to estimate early-life (e.g., parental education, whether participant ever went hungry) and adult (participant's education, main occupation) SES factors and their associations with cross-sectional and longitudinal cognitive outcomes of episodic memory, semantic memory, executive function, and spatial ability.

RESULTS

Child and adult factors were strongly related to domain-specific cognitive intercepts (0.20-0.48 SD per SD of SES factor); in contrast, SES factors were not related to global cognitive change (0.001-0.01 SD per year per SD of SES factor). Adulthood SES mediated a large percentage (68-75%) of the total early-life effect on cognition.

CONCLUSIONS

Early-life sociocontextual factors are more strongly associated with cross-sectional late-life cognitive performance compared to cognitive change; this effect is largely mediated through associations with adulthood SES.

Spatial distributions in disaster risk vulnerability for people with disabilities in the U.S

BACKGROUND

The spread of Coronavirus Disease 2019 (COVID-19) in the United States has centered the role of natural hazards such as pandemics into the public health sphere. The impacts of these hazards disproportionately affect people with disabilities, who are frequently in situations of social, political, or economic disadvantage. Because of these disadvantages, people with disabilities may have less access to necessary resources and services, putting them at risk due to unmet health needs. These disparities in access also highlight important regional, state, and county-level differences with regards to vulnerability and preparedness for natural hazards.

OBJECTIVE

The objective of this paper is to examine the relationship between disability and disaster risk in the United States. We examine the geographic variation in the relationship between risk from natural disasters and the percentage of people with disabilities living in a community. Because emergency management functions in the U.S. are directed and enacted at the county level, we also explore how these relationships change across U.S. counties. In addition to the overall prevalence of people with disabilities, we disaggregate the population of people with disabilities by gender, race, ethnicity, age, and disability impairment type.

METHODS

To measure risk of natural hazards, we use Expected Annual Loss index, a component of the 2020 National Risk Index, developed by Federal Emergency Management Agency, which identifies communities most at risk to18 natural hazards. We measure the percent of people with disabilities per county using the American Community Survey. We estimate the nationwide relationship between the proportion of people with disabilities and risk of natural hazards using ordinary least squares regression. To explore geographic differences in these relationships across the United States, we use a geographically weighted regression model to estimate local relationships for each county in the contiguous United States. We use mapping techniques to display regional differences across different disability demographic groups.

RESULTS

Counties with higher percentages of people with disabilities have a lower risk of natural disasters. Across the United States, a one percent increase in prevalence of people with disabilities in a county is associated with two percent decrease in the natural hazard risk score. Small but statistically significant regional differences exist as well. County-specific estimates range from a five percent decrease to a one percent increase. Stronger associations between risk and the prevalence of people with disabilities are observed in the Midwest and parts of the Southwest and West, whereas the relationship across racial groups is more scattered across the United States.

CONCLUSION

In this study, nationwide results suggest that people with disabilities are more likely to live in communities with lower risk of natural hazards, but this relationship differs across U.S. counties and by demographic subgroups. These findings represent a contribution in further understanding the health and well-being of people with disabilities in the United States and the geographic variation therein.

Associations of local area level new deal employment in childhood with late life cognition: evidence from the census-linked health and retirement study

BACKGROUND

Emergency employment programmes during the 1930s and 1940s invested income, infrastructure and social services into communities affected by the Great Depression. We estimate the long-term associations of growing up in an area exposed to New Deal emergency employment in 1940 with cognitive functioning in later life.

METHODS

Members of the Health and Retirement Study cohort (N=5095; mean age 66.3 at baseline) who were age 0-17 in 1940 were linked to their census record from that year, providing prospective information about childhood contextual and family circumstances. We estimated the association between subcounty-level emergency employment participation in 1940 and baseline cognition and rate of cognitive decline between 1998 and 2016.

RESULTS

Compared with those living in the lowest emergency employment quintile in 1940, those who were exposed to moderate levels of emergency employment (third quintile) had better cognitive functioning in 1998 (b=0.092 SD, 95% CI 0.011 to 0.173), conditional on sociodemographic factors. This effect was modestly attenuated after adjusting for respondents' adult education, finances and health factors. There were no significant effects of area-level emergency employment on rate of cognitive decline.

CONCLUSIONS

Exposure to New Deal employment policies during childhood is associated with long-term cognitive health benefits. This is partially explained by increases in educational attainment among those with greater levels of emergency employment activity in the place where they were raised. Future research should investigate which types of New Deal investments may most be related to long-term cognitive health, or if the associations we observe are due to co-occurring programmes.

Apolipoprotein E (APOE) genotype, dementia, and memory performance among Caribbean Hispanic versus US populations

INTRODUCTION

Apolipoprotein E (APOE) is considered the major susceptibility gene for developing Alzheimer's disease. However, the strength of this risk factor is not well established across diverse Hispanic populations.

METHODS

We investigated the associations among APOE genotype, dementia prevalence, and memory performance (immediate and delayed recall scores) in Caribbean Hispanics (CH), African Americans (AA), Hispanic Americans (HA) and non-Hispanic White Americans (NHW). Multivariable logistic regressions and negative binomial regressions were used to examine these associations by subsample.

RESULTS

Our final dataset included 13,516 participants (5198 men, 8318 women) across all subsamples, with a mean age of 74.8 years. Prevalence of APOE ε4 allele was similar in CHs, HAs, and NHWs (21.8%-25.4%), but was substantially higher in AAs (33.6%; P < 0.001). APOE ε4 carriers had higher dementia prevalence across all groups.

DISCUSSION

APOE ε4 was similarly associated with increased relative risk of dementia and lower memory performance in all subsamples.

Dementia Attributable Healthcare Utilizations in the Caribbean versus United States

BACKGROUND

Despite the high burden of Alzheimer's disease and other dementias among the Hispanic population worldwide, little is known about how dementia affects healthcare utilizations among this population outside of the US, in particular among those in the Caribbean region.

OBJECTIVE

This study examines healthcare utilization associated with Alzheimer's disease and other dementias among older adults in the Caribbean as compared to the US.

METHODS

We conducted harmonized analyses of two population-based surveys, the 10/66 Dementia Group Research data collected in Dominican Republic, Cuba, and Puerto Rico, and the US-based Health and Retirement Study. We examined changes in hospital nights and physician visits in response to incident and ongoing dementias.

RESULTS

Incident dementia significantly increased the risk of hospitalization and number of hospital nights in both populations. Ongoing dementia increased the risk of hospitalization and hospital nights in the US, with imprecise estimates for the Caribbean. The number of physician visits was elevated in the US but not in the Caribbean.

CONCLUSIONS

The concentration of increased healthcare utilization on hospital care and among patients with incident dementia suggests an opportunity for improved outpatient management of new and existing dementia patients in the Caribbean.

Effects of Sex, APOE4, and Lifestyle Activities on Cognitive Reserve in Older Adults

BACKGROUND AND OBJECTIVES

Lifestyle activities, such as physical activity and cognitive stimulation, may mitigate age-associated cognitive decline, delay dementia onset, and increase cognitive reserve. Whether the association between lifestyle activities and cognitive reserve differs by sex and APOE4 status is an understudied yet critical component for informing targeted prevention strategies. The current study examined interactions between sex and physical or cognitive activities on cognitive reserve for speed and memory in older adults.

METHODS

Research participants with unimpaired cognition, mild cognitive impairment, or dementia from the Washington Heights-Inwood Columbia Aging Cohort were included in this study. Cognitive reserve scores for speed and memory were calculated by regressing out hippocampal volume, total gray matter volume, and white matter hyperintensity volume from composite cognitive scores for speed and memory, respectively. Self-reported physical activity was assessed using the Godin Leisure Time Exercise Questionnaire, converted to metabolic equivalents (METS). Self-reported cognitive activity (COGACT) was calculated as the sum of 3 yes/no questions. Sex by activity interactions and sex-stratified analyses were conducted using multivariable linear regression models, including a secondary analysis with APOE4 as a moderating factor.

RESULTS

Seven hundred fifty-eight participants (mean age = 76.11 ± 6.31 years, 62% women) were included in this study. Higher METS was associated with greater speed reserve in women (β = 0.04, CI 0.0-08) but not in men (β = 0.004, CI -0.04 to 0.05). METS was not associated with memory reserve in women or men. More COGACT was associated with greater speed reserve in the cohort (β = 0.13, CI 0.05-0.21). More COGACT had a trend for greater memory reserve in women (β = 0.06, CI -0.02 to 0.14) but not in men (β = -0.04, CI -0.16 to 0.08). Only among women, APOE4 carrier status attenuated relationships between METS and speed reserve (β = -0.09, CI -0.22 to 0.04) and between COGACT and both speed (β = -0.26, CI -0.63 to 0.11) and memory reserves (β = -0.20, CI -0.50.0 to 093).

DISCUSSION

The associations of self-reported physical and cognitive activities with cognitive reserve are more pronounced in women, although APOE4 attenuates these associations. Future studies are needed to understand the causal relationship among sex, lifestyle activities, and genetic factors on cognitive reserve in older adults to best understand which lifestyle activities may be most beneficial and for whom.

Associations between education and dementia in the Caribbean and the United States: An international comparison

INTRODUCTION

Despite high dementia prevalence in Hispanic populations globally, especially Caribbean Hispanics, no study has comparatively examined the association between education and dementia among Hispanics living in the Caribbean Islands and older adults in the United States.

METHODS

We used data on 6107 respondents aged 65 and older in the baseline wave of the population-based and harmonized 10/66 survey from Cuba, the Dominican Republic, and Puerto Rico, collected between 2003 and 2008, and 11,032 respondents aged 65 and older from the U.S.-based Health and Retirement Study data in 2014, a total of 17,139 individuals. We estimated multivariable logistic regression models examining the association between education and dementia, adjusted for age, income, assets, and occupation. The models were estimated separately for the Caribbean population (pooled and by setting) and the U.S. population by race/ethnicity (Hispanic, Black, and White), followed by pooled models across all populations.

RESULTS

In the Caribbean population, the relative risk of dementia among low versus high educated adults was 1.45 for women (95% confidence interval [CI] 1.17, 1.74) and 1.92 (95% CI 1.35, 2.49) for men, smaller compared to those in the United States, especially among non-Hispanic Whites (women: 2.78, 95% CI 1.94, 3.61; men: 5.98, 95% CI 4.02, 7.95).

DISCUSSION

The differential associations between education and dementia across the Caribbean and US settings may be explained by greater disparities in social conditions in the United States compared to the Caribbean, such as access to health care, healthy behaviors, and social stressors, which serve as potentially important mediators.

Longitudinal Relationship of Leisure Activity Engagement with Cognitive Performance among Non-Demented, Community-Dwelling Older Adults

BACKGROUND AND OBJECTIVES

Leisure activity engagement (LAE) may reduce the risk of incident dementia. However, cognitive performance may predict LAE change. We evaluated the temporal ordering of overall and subtypes of LAE (intellectual, physical, and social) and cognitive performance (global, language, memory, and visuospatial function) among non-demented older adults.

RESEARCH DESIGN AND METHODS

The Washington Heights-Inwood Columbia Aging Project concurrently administered a survey measure of 13 leisure activities and a neuropsychological battery every 18-24 months for up to 14 years to 5,384 racially and ethnically diverse participants. We used parallel process conditional latent growth curve models to examine temporal ordering in the overall sample and within baseline diagnostic groups (MCI vs. cognitively normal).

RESULTS

Levels and changes of overall and subtypes of LAE were positively correlated with cognitive performance in the overall sample and within each diagnostic group. In the overall sample, higher initial memory was associated with slower declines in social LAE (Estimate=0.019, 95% Confidence Interval, CI: 0.001, 0.037). Among MCI, higher initial physical LAE was associated with slower declines in memory (Estimate=0.034, 95% CI: 0.001, 0.067), but higher initial intellectual LAE was related to steeper declines in visuospatial function (Estimate=-0.028, 95% CI: -0.052, -0.004). Among cognitively normal, higher initial memory was associated with slower declines in intellectual LAE (Estimate=0.012, 95% CI: 0.002, 0.022).

DISCUSSION AND IMPLICATIONS

Dynamic interplay of LAE with cognitive performance was observed across diagnostic groups. Levels of LAE subtypes could be more predictive of change in certain cognitive domains within older adults with MCI.

Gender Differences in the Life Course Effects of Unemployment on Mid- and Later-Life Health

There is substantial evidence that unemployment is associated with adverse health. Given different lifetime employment patterns, these effects may differ between men and women. However, current studies often only characterize unemployment as a one-time shock, and measure the effects on health shortly thereafter. Using unique data available from The National Longitudinal Study of Youth 1979, we characterize employment trajectories for a nationally-representative sample of American men and women for every week of their lives between the ages of 18 and 50 years old. We then explore associations between unemployment and a number of health conditions including cancer, hypertension, diabetes, and depression at age 50--when the onset of chronic health conditions often begins—to examine the cumulative effects of unemployment over the life course on later-life health. We find that men and women have different patterns of lifetime unemployment and that these patterns have strong associations with poorer health at age 50.

Short-Term Mental Health Sequelae of Bereavement Predict Long-Term Physical Health Decline in Older Adults: U.S. Health and Retirement Study Analysis

OBJECTIVES

Spousal death is a common late-life event with health-related sequelae. Evidence linking poor mental health to disease suggests the hypothesis that poor mental health following death of a spouse could be a harbinger of physical health decline. Thus, identification of bereavement-related mental health symptoms could provide an opportunity for prevention.

METHODS

We analyzed data from N = 39,162 individuals followed from 1994 to 2016 in the U.S. Health and Retirement Study; N = 5,061 were widowed during follow-up. We tested change in mental and physical health from prebereavement through the 5 years following spousal death.

RESULTS

Bereaved spouses experienced an increase in depressive symptoms following their spouses' deaths but the depressive shock attenuated within 1 year. Bereaved spouses experienced increases in disability, chronic-disease morbidity, and hospitalization, which grew in magnitude over time, especially among older respondents. Bereaved spouses were at increased risk of death compared to nonbereaved respondents. The magnitude of depressive symptoms in the immediate aftermath of spousal death predicted physical-health decline and mortality risk over 5 years of follow-up.

DISCUSSION

Bereavement-related depressive symptoms indicate a risk for physical health decline and death in older adults. Screening for depressive symptoms in bereaved older adults may represent an opportunity for intervention to preserve healthy life span.

Late-Life Physical and Cognitive Activities Independently Contribute to Brain and Cognitive Resilience

BACKGROUND

Active lifestyles are related to better cognitive aging outcomes, yet the unique role of different types of activity are unknown.

OBJECTIVE

To examine the independent contributions of physical (PA) versus cognitive (CA) leisure activities to brain and cognitive aging.

METHODS

Independent samples of non-demented older adults from University of California, San Francisco Hillblom Aging Network (UCSF; n = 344 typically aging) and University of California, Davis Diversity cohort (UCD; n = 485 normal to MCI) completed: 1) self-reported engagement in current PA and CA (UCSF: Physical Activity Scale for the Elderly and Cognitive Activity Scale; UCD: Life Experiences Assessment Form); 2) neuropsychological batteries; and 3) neuroimaging total gray matter volume, white matter hyperintensities, and/or global fractional anisotropy. PA and CA were simultaneously entered into multivariable linear regression models, adjusting for demographic characteristics and functional impairment severity.

RESULTS

Brain outcomes: In UCSF, only PA was positively associated with gray matter volume and attenuated the relationship between age and fractional anisotropy. In UCD, only CA was associated with less white matter hyperintensities and attenuated the relationship between age and gray matter volume. Cognitive outcomes: In both cohorts, greater CA, but not PA, related to better cognition, independent of age and brain structure. In UCSF, CA attenuated the relationship between fractional anisotropy and cognition. In UCD, PA attenuated the association between white matter hyperintensities and cognition.

CONCLUSIONS

Although their specificity was not easily teased apart, both PA and CA are clearly related to better brain and cognitive resilience markers across cohorts with differing educational, racial, and disease statuses. PA and CA may independently contribute to converging neuroprotective pathways for brain and cognitive aging.

INTEGRATIVE ANALYSIS OF ALZHEIMER’S DISEASE GWAS TO DEVELOP A NEW POLYGENIC PREDICTOR AND TEST BIOSOCIAL ETIOLOGY

Alzheimer’s disease (AD) has genetic and environmental causes and etiology is thought to reflect interplay among these factors. A barrier to integration of genetic and environmental etiologic factors in research to inform prevention and intervention is poor understanding of AD genetics beyond APOE4. We used the new Genomic SEM methodology to conduct integrative analysis of results from several AD genome-wide association studies (GWAS), including brain-imaging and autopsy AD GWAS, to derive a novel, polygenic genetic predictor of AD. We applied this polygenic predictor in the US Health and Retirement Study to test associations with (1) cognitive aging measured from repeated-measures longitudinal cognitive-test data; and (2) blood-chemistry-based biological age algorithms. In further exploratory analysis, we tested if risk measured by the novel AD polygenic predictor was correlated with and/or buffered by a known environmental factor influencing AD etiology, life-course socioeconomic position. Results map new directions for biosocial AD research.

PHYSICAL VERSUS COGNITIVE ACTIVITY FOR SUCCESSFUL AGING: BRAIN MAINTENANCE OR COGNITIVE RESERVE?

Mechanisms by which physical (PA) and cognitive (CA) activities promote healthy cognitive aging are unknown. We examined independent contributions of PA and CA to “brain maintenance” (MRI markers of brain integrity) versus “cognitive reserve” (better cognition than predicted by brain integrity) in two independent samples of non-demented older adults (UCSF n=344; UCD n=482). In UCSF, only PA was positively associated with white matter (WM) integrity, while CA attenuated the relationship between WM and cognition. This pattern suggests PA supports brain maintenance, while CA contributes to cognitive reserve. In UCD, CA was positively associated with total gray matter volume; PA was positively associated with age-related WM integrity, and attenuated the association between WM and cognition. This indicates that both PA and CA support brain maintenance, with PA more strongly related to cognitive reserve. There may be preferential, but overlapping pathways by which PA and CA maintain age-related brain and cognitive health.

MENTAL AND PHYSICAL HEALTH SEQUELAE OF BEREAVEMENT IN OLDER ADULTS: U.S. HEATH AND RETIREMENT STUDY ANALYSIS

Death of a spouse (bereavement) is associated with poor mental and physical health outcomes in older adults. But it is unknown how mental- and physical-health sequelae of bereavement are related and the clinical significance of bereavement-related depression has been questioned. We analyzed US Health and Retirement Study (HRS) data tracking mental and physical health of 36,034 older adults during 1992-2016. Post-bereavement data were available for N=4,985 participants with recorded date of spousal death. We analyzed longitudinal repeated-measures data on survivors’ depression, disease, disability, and mortality. Bereavement effects on depression were immediate, but short-lived, attenuating within the year. In contrast, bereavement effects on physical health and mortality persisted over follow-up. Critically, the magnitude of short-lived effects on depression correlated with the magnitude of longer-lasting effects on disease, disability, and mortality. Results reveal connections between mental and physical health and aging and suggest bereavement-related depression as a biomarker of enduring health risk.

Lifecourse epidemiology matures: Commentary on Zhang et al. "Early-life socioeconomic status, adolescent cognitive ability, and cognition in late midlife"

The effect of education on late life cognition has attracted substantial attention in lifecourse epidemiology, in part because of its relevance for understanding the effect of education on dementia. Although numerous studies document an association between education and later life cognition, these studies are potentially confounded by early life socioeconomic position and cognition. Good measures of these early life constructs are rarely available in data sets assessing cognition in late life. A further body of evidence has taken advantage of compulsory schooling law (CSL) instrumental variables (IV), although these estimates have been criticized based on questions about the validity of CSL IVs. In this issue of the Journal, Zhang et al. took advantage of the Wisconsin Longitudinal Study to control for both prospectively measured adolescent IQ and early life socioeconomic status in an analysis evaluating the effect of education on cognitive scores in late middle age (Zhang et al., 2019; IN THIS ISSUE). Their results indicate a moderate effect of each additional year of education on later life cognition, of approximately 0.1-0.15 standard deviations per year of schooling. These estimates are remarkably aligned with findings from prior observational designs and from the CSL IV studies. Although criticisms of any individual study are plausible, this new study complements the body of prior evidence to provide compelling evidence for the benefits of education on late life cognition.

The Contributions of Active Spanish-English Bilingualism to Cognitive Reserve among Older Hispanic Adults Living in California

Objective

Bilinguals may be able to retain similar levels of cognitive functioning given age and/or Alzheimer’s Disease-related neurodegeneration, compared to monolinguals. Many studies have yielded equivocal findings that may be explained by within-group differences among bilinguals, such as frequency of language use. The current study aimed to clarify the role of frequency of bilingual language use (i.e., active versus passive) in the association of brain structure and memory. We hypothesized that active bilinguals would demonstrate better memory performance compared to passive bilinguals and monolinguals, and that active bilingualism would buffer the effects of temporal lobe integrity on memory.

Participants and Method

In a longitudinal aging study, 217 older Hispanic adults (Age M = 74 years, SD = 6; 70% women) underwent neuropsychological evaluation and 1.5T MR imaging. Bilingualism was determined by self-reported use of English and Spanish. Active bilinguals reported using both languages daily. Multiple regression tested main effects and interactions of bilingualism and entorhinal cortical thickness on semantic and episodic memory, adjusted for age, sex/gender, and education.

Results

Bilingualism was associated with better semantic memory(F[2,209] = 6.25, p = .002) but not with episodic memory(F[2,209)] = 0.34, p = .71). There was a significant bilingualism X entorhinal cortical thickness interaction on semantic memory (β = -.26, p = .02), indicating that active bilinguals were better able to maintain cognitive functioning with lower cortical thickness, compared to passive bilinguals and monolinguals.

Conclusions

Active bilingualism may protect semantic memory against cortical thinning of the entorhinal cortex. Future studies will explore whether this relationship remains after accounting for additional environmental and sociocultural factors (e.g., immigrant status) that influence the ability or opportunity to become bilingual, and whether active bilingualism affects cognitive trajectory in late life.

Predictors and Implications of Accelerated Cognitive Aging

Aging is a major risk factor for both normal and pathological cognitive decline. However, individuals vary in their rate of age-related decline. We developed an easily interpretable composite measure of cognitive age, and related both the level of cognitive age and cognitive slope to sociodemographic, genetic, and disease indicators and examine its prediction of dementia transition. Using a sample of 19,594 participants from the Health and Retirement Study, cognitive age was derived from a set of performance tests administered at each wave. Our findings reveal different conclusions as they relate to levels versus slopes of cognitive age, with more pronounced differences by sex and race/ethnicity for absolute levels of cognitive decline rather than for rates of declines. We also find that both level and slope of cognitive age are inversely related to education, as well as increased for persons with APOE ε4 and/or diabetes. Finally, results show that the slope in cognitive age predicts subsequent dementia among non-demented older adults. Overall, our study suggests that this measure is applicable to cross-sectional and longitudinal studies on cognitive aging, decline, and dementia with the goal of better understanding individual differences in cognitive decline.

Mortality selection in a genetic sample and implications for association studies

Background

Mortality selection occurs when a non-random subset of a population of interest has died before data collection and is unobserved in the data. Mortality selection is of general concern in the social and health sciences, but has received little attention in genetic epidemiology. We tested the hypothesis that mortality selection may bias genetic association estimates, using data from the US-based Health and Retirement Study (HRS).

Methods

We tested mortality selection into the HRS genetic database by comparing HRS respondents who survive until genetic data collection in 2006 with those who do not. We next modelled mortality selection on demographic, health and social characteristics to calculate mortality selection probability weights. We analysed polygenic score associations with several traits before and after applying inverse-probability weighting to account for mortality selection. We tested simple associations and time-varying genetic associations (i.e. gene-by-cohort interactions).

Results

We observed mortality selection into the HRS genetic database on demographic, health and social characteristics. Correction for mortality selection using inverse probability weighting methods did not change simple association estimates. However, using these methods did change estimates of gene-by-cohort interaction effects. Correction for mortality selection changed gene-by-cohort interaction estimates in the opposite direction from increased mortality selection based on analysis of HRS respondents surviving through 2012.

Conclusions

Mortality selection may bias estimates of gene-by-cohort interaction effects. Analyses of HRS data can adjust for mortality selection associated with observables by including probability weights. Mortality selection is a potential confounder of genetic association studies, but the magnitude of confounding varies by trait.

Characterizing the genetic influences on risk aversion

Risk aversion has long been cited as an important factor in retirement decisions, investment behavior, and health. Some of the heterogeneity in individual risk tolerance is well understood, reflecting age gradients, wealth gradients, and similar effects, but much remains unexplained. This study explores genetic contributions to heterogeneity in risk aversion among older Americans. Using over 2 million genetic markers per individual from the U.S. Health and Retirement Study, I report results from a genome-wide association study (GWAS) on risk preferences using a sample of 10,455 adults. None of the single-nucleotide polymorphisms (SNPs) are found to be statistically significant determinants of risk preferences at levels stricter than 5 × 10(-8). These results suggest that risk aversion is a complex trait that is highly polygenic. The analysis leads to upper bounds on the number of genetic effects that could exceed certain thresholds of significance and still remain undetected at the current sample size. The findings suggest that the known heritability in risk aversion is likely to be driven by large numbers of genetic variants, each with a small effect size.