Lifecourse socioeconomic changes and late-life cognition in a cohort of U.S.-born and U.S. immigrants: findings from the KHANDLE study

Life course socioeconomic position and cognitive aging in later life: A scoping review

BACKGROUND AND OBJECTIVES

Low socioeconomic position (SEP) throughout the life course is related to poorer cognitive health in later life, but debate ensues on the life course models for this association. To advance inquiry on the topic, we conducted a scoping review.

RESEARCH DESIGN AND METHODS

We examined the association between life course SEP and cognitive function in later life in observational studies-considering cognition both as a cross-sectional level and as a longitudinal trajectory across cognitive domains-and assessed whether the empirical evidence supported life course models. We focused on studies in the general population with cognition measured in the second half of life (45 +). Forty-two studies (21 datasets) were included representing 595,276 participants (201,375 across unique datasets) from 46 countries.

RESULTS

For cognitive level, studies consistently found associations between SEP at various stages of the life course, both in overall cognition and across specific cognitive domains. These associations were generally robust to confounding and mediating factors. For cognitive trajectory, studies showed inconclusive associations with SEP across life course and across cognitive domains. Results supported the sensitive period, pathway, and accumulation models, but not the critical period model. Results supported that education acts as a pathway (and potential mediator) in the association between early-life SEP and later-life cognition.

DISCUSSION AND IMPLICATIONS

SEP throughout the life course has a robust association with later-life cognitive level, but not decline. Early-life cognitive enrichment for young people raised in socioeconomically disadvantaged households may reduce the SEP gap in cognitive functioning during later life.

"Rest of the folks are tired and weary": The impact of historical lynchings on biological and cognitive health for older adults racialized as Black

Childhood structural racism may lead to poorer health and longevity for individuals racialized as Black. Racism-related stress cumulatively taxes the body resulting in worsening biological and cognitive health. This study examines the association between state-level exposure to historical lynchings (adverse childhood racism for modern older adults), with C-reactive protein (CRP, a marker of systemic inflammation), and global cognitive performance (modified TICS). We linked the percentage of lynchings of people racialized as Black at the state-level between 1882 and 1968 from the Archives at Tuskegee Institute with repeated CRP and cognitive test scores at baseline (2006/2008), year 4 (2010/2012), and year 8 (2014/2016) for a national sample of older adults in the Health and Retirement Study (N = 10,500, aged >50). In multivariable generalized estimating equation models, we compared participants (by racialized group) living in states with high lynching proportions (>50th percentile) on changes in CRP and cognitive test scores adjusting for demographics, health conditions, and behaviors. Mean age was 69 (SD = 9.9) and most participants were cisgender women (59%). On average participants racialized as non-LatinX Black living in states with high lynching proportions experienced 18.5% (95% CI 3%, 36%) higher CRP levels and -0.92 (95% CI -1.34, -0.50) lower cognitive test scores than participants racialized as non-LatinX Black that lived in states with lower lynching proportions. As artist Marvin Gaye sang in Flyin' High (in the Friendly Sky), "Rest of the folks are tired and weary," which describes how adverse childhood racism is associated with inflammation and dementia risk for people racialized as Black.

Childhood Community Disadvantage and MRI-Derived Structural Brain Integrity After Age 65 Years

Importance

Prior studies associate late-life community disadvantage with worse brain health. It is relatively unknown if childhood community disadvantage associates with late-life brain health.

Objective

To test associations between childhood residence in an economically disadvantaged community, individual income and education, and late-life cortical brain volumes and white matter integrity.

Design, Setting, and Participants

This cohort study was conducted in the ongoing harmonized cohorts KHANDLE (Kaiser Healthy Aging and Diverse Life Experiences Study; initiated 2017) and STAR (Study of Healthy Aging in African Americans; initiated 2018) using all available data collected out of a regional integrated health care delivery network in California between cohort initiation and analysis initiation in June 2023. Eligible participants were Kaiser Permanente Northern California member ages 65 years or older. Data were analyzed between June and November 2023.

Exposure

Residence at birth was geocoded and linked to historical Area Deprivation Indices (ADI). ADI is a nationally ranked percentile; community disadvantage was defined as ADI of 80 or higher.

Main Outcomes and Measures

Regional brain volumes and white matter integrity measures were derived from a random subset of participants who underwent 3T magnetic resonance imaging. Models adjusted for race and ethnicity, sex, and parental education.

Results

Of a total 2161 individuals in the combined cohort, 443 individuals were eligible for imaging (mean [SD] age, 76.3 [6.5] years; 253 female [57.1%]; 56 Asian [12.6%], 212 Black [47.9%], 67 Latino [15.1%], 109 White [24.6%]). Imaging participants had a mean (SD) 15.0 (2.5) years of education, and 183 (41.3%) earned $55 000 to $99 999 annually. Fifty-four participants (12.2%) resided in a disadvantaged childhood community. Childhood community disadvantage was associated with smaller gray matter volumes overall (-0.39 cm3; 95% CI, -0.65 to -0.10 cm3) and in the cerebellum (-0.39 cm3; 95% CI, -0.66 to -0.09 cm3), hippocampus (-0.37 cm3; 95% CI, -0.68 to -0.04 cm3), and parietal cortex (-0.25 cm3; 95% CI, -0.46 to -0.04 cm3) and larger mean lateral ventricle (0.44 cm3; 95% CI, 0.12 to 0.74 cm3), third ventricle (0.28 cm3; 95% CI, 0.03 to 0.55 cm3), and white matter hyperintensity volume (0.31 cm3; 95% CI, 0.06 to 0.56 cm3). Educational attainment and late-life income did not mediate these associations.

Conclusions and Relevance

In this cohort study of racially and ethnically diverse health plan members, childhood community disadvantage was associated with worse late-life brain health independent of individual socioeconomic status. Future work should explore alternative pathways (eg, cardiovascular health) that may explain observed associations.

Life course financial mobility and later-life memory function and decline by gender, and race and ethnicity: an intersectional analysis of the US KHANDLE and STAR cohort studies

BACKGROUND

Intersectionality has rarely been considered in research studies of cognitive ageing. We investigated whether life-course financial mobility is differentially associated with later-life memory function and decline across intersectional identities defined by gender, and race and ethnicity.

METHODS

Data were from two harmonised multiethnic cohorts (the Kaiser Healthy Aging and Diverse Life Experiences cohort and the Study of Healthy Aging in African Americans cohort) in northern California, USA (n=2340). Life-course financial mobility, measured using a combination of self-reported financial capital measures in childhood (from birth to age 16 years) and later adulthood (at the cohort baseline) was defined as consistently high, upwardly mobile, downwardly mobile, or consistently low. We clustered individuals into 32 strata representing intersectional identities defined by life-course financial mobility combined with gender, and race and ethnicity. Verbal episodic memory was assessed using the Spanish and English Neuropsychological Assessment Scales over four waves from 2017 to 2023. Adjusted mixed-effects linear regression models were estimated with and without fixed effects of gender, race and ethnicity, and financial mobility, to evaluate whether the random effects of the intersectional identity strata contributed variance to memory beyond individual fixed effects.

FINDINGS

Mean age was 73·6 years (SD 8·1). Of 2340 individuals, 1460 (62·4%) were women, 880 (37·6%) were men, 388 (16·6%) were Asian, 1136 (48·5%) were Black, 334 (14·3%) were Latinx, and 482 (20·6%) were White. Consistently low and downwardly mobile financial capital were strongly negatively associated with later-life memory at baseline (-0·162 SD units [95% CI -0·273 to -0·051] for consistently low and -0·171 [-0·250 to -0·092] for downwardly mobile), but not rate of change over time. Intersectional identities contributed 0·2% of memory variance after accounting for the fixed effects of gender, race and ethnicity, and financial mobility.

INTERPRETATION

Consistently low and downward life-course financial mobility are associated with lower later-life memory function. Intersectional identities defined by financial mobility in addition to gender, and race and ethnicity, contribute negligible additional variance to later-life memory in this study setting.

FUNDING

US National Institute on Aging, US National Institutes of Health.

The associations of socioeconomic position with structural brain damage and connectivity and cognitive functioning: The Maastricht Study

BACKGROUND

Socioeconomic inequalities in cognitive impairment may partly act through structural brain damage and reduced connectivity. This study investigated the extent to which the association of early-life socioeconomic position (SEP) with later-life cognitive functioning is mediated by later-life SEP, and whether the associations of SEP with later-life cognitive functioning can be explained by structural brain damage and connectivity.

METHODS

We used cross-sectional data from the Dutch population-based Maastricht Study (n = 4,839; mean age 59.2 ± 8.7 years, 49.8% women). Early-life SEP was assessed by self-reported poverty during childhood and parental education. Later-life SEP included education, occupation, and current household income. Participants underwent cognitive testing and 3-T magnetic resonance imaging to measure volumes of white matter hyperintensities, grey matter, white matter, cerebrospinal fluid, and structural connectivity. Multiple linear regression analyses tested the associations between SEP, markers of structural brain damage and connectivity, and cognitive functioning. Mediation was tested using structural equation modeling.

RESULTS

Although there were direct associations between both indicators of SEP and later-life cognitive functioning, a large part of the association between early-life SEP and later-life cognitive functioning was explained by later-life SEP (72.2%). The extent to which structural brain damage or connectivity acted as mediators between SEP and cognitive functioning was small (up to 5.9%).

CONCLUSIONS

We observed substantial SEP differences in later-life cognitive functioning. Associations of structural brain damage and connectivity with cognitive functioning were relatively small, and only marginally explained the SEP gradients in cognitive functioning.

"Hang Ups, Let Downs, Bad Breaks, Setbacks": Impact of Structural Socioeconomic Racism and Resilience on Cognitive Change Over Time for Persons Racialized as Black

Introduction

Older adults racialized as Black experience higher rates of dementia than those racialized as White. Structural racism produces socioeconomic challenges, described by artist Marvin Gaye as "hang ups, let downs, bad breaks, setbacks" that likely contribute to dementia disparities. Robust dementia literature suggests socioeconomic factors may also be key resiliencies.

Methods

We linked state-level data reflecting the racialized landscape of economic opportunity across the 20th Century from the U.S. Census (1930-2010) with individual-level data on cognitive outcomes from the U.S. Health and Retirement Study participants racialized as Black. A purposive sample of participants born after the Brown v. Board ruling (born 1954-59) were selected who completed the modified Telephone Interview for Cognitive Status between 2010 and 2020 (N=1381). We tested associations of exposure to structural racism and resilience before birth, and during childhood, young-adulthood, and midlife with cognitive trajectories in mid-late life using mixed-effects regression models.

Results

Older adults born in places with higher state-level structural socioeconomic racism experienced a more rapid cognitive decline in later life compared to those with lower levels of exposure. In addition, participants born in places with higher levels of state-level structural socioeconomic resilience experienced slower cognitive change over time than their counterparts.

Discussion

These findings reveal the impact of racist U.S. policies enacted in the past that influence cognitive health over time and dementia risk later in life.

Dietary Adherence and Cognitive Performance in Older Adults by Nativity Status: Results from the National Health and Nutrition Examination Survey (NHANES), 2011-2014

Although adherence to dietary guidelines is associated with better cognitive performance, there may be differences by nativity status. This study aimed to investigate the association between adherence to the healthy eating index (HEI) and cognitive performance (CP) among United States (US)-born and foreign-born older adults (60+ years). Data were obtained from the 2011-2014 NHANES (n = 3065). Dietary adherence was assessed with HEI quintiles. CP (adequate vs. low) was examined using word listing (CERAD), animal naming (AFT), and the digit symbol substitution test (DSST). Weighted multivariable logistic regressions were used to examine associations. The US-born participants in higher dietary quintiles had adequate CP when compared to foreign-born participants. In adjusted models, the US-born participants in the highest HEI quintile had increased odds of adequate DSST scores (odds ratio: 1.95, 95% confidence interval: 1.15-3.28) compared with those in the lowest quintile. Patterns of association were generally reversed for foreign-born participants and were non-statistically significant. Future research should consider the influence of diets in delaying or preventing decline in cognition and evaluate nutritional factors that contribute to cognitive outcomes for the foreign-born population.

Life-course socio-economic status and its impact on functional health of Portuguese older adults

Functional health is arguably one of the most important health indicators for older adults, because it assesses physical, cognitive and social functions in combination. However, life-course circumstances may impact this multidimensional construct. The aim of the present study was to assess the relationship between life-course socio-economic status (SES) and different dimensions of functional health in older adults. Data on 821 Portuguese adults aged 50 years and over in 2013-2015 were analysed. Life-course SES was computed using participants' paternal occupation (non-manual (nm); manual (m)) and own occupation (nm; m), resulting in four patterns: stable high (nm + nm), upward (m + nm), downward (nm + m) and stable low (m + m). Functional health included physical and mental functioning, cognitive function, handgrip strength, and walking speed. Linear (beta coefficients) and logistic regressions (odds ratios) were used to estimate the association between life-course SES and functional health.Overall, those who accumulated social disadvantage during life-course presented worse functional health than those with stable high SES (stable low - SF-36 physical functioning: β = -9.75; 95% CI: -14.34; -5.15; SF-36 mental health: β = -7.33; 95% CI: -11.55; -3.11; handgrip strength: β = -1.60; 95% CI: -2.86; -0.35; walking time, highest tertile: OR = 5.28; 95% CI: 3.07; 9.09). Those with an upward SES were not statistically different from those in the stable high SES for most of the health outcomes; however, those with an upward SES trajectory tended to have higher odds of cognitive impairment (OR = 1.75; 95% CI: 0.96; 3.19). A downward SES trajectory increased the odds of slower walking speed (OR = 4.62; 95% CI: 1.78; 11.95). A disadvantaged life-course SES impacts older adults' physical and mental functioning. For some outcomes, this was attenuated by a favourable adulthood SES but those with a stable low SES consistently presented worse functional health.

The Add Health Parent Study: A Biosocial Resource for the Study of Multigenerational Racial/Ethnic Disparities in Alzheimer's Disease and Alzheimer's Disease-Related Dementias

Background

Alzheimer's disease and Alzheimer's disease related dementias (AD/ADRD) have increased in prevalence.

Objective

This article describes the Add Health Parent Study (AHPS) Phase 2, a study of social, behavioral, and biological factors influencing healthy aging and risk for AD/ADRD, in a national sample of adults aged 58-90.

Methods

Sample members are parents of the National Longitudinal Study of Adolescent to Adult Health (Add Health) cohort, initially interviewed in Add Health in midlife (1994-95). AHPS Phase 1 (2015-17) collected longitudinal data on a random subsample of parents and their spouse/partners, who were mostly Non-Hispanic (NH) White. AHPS Phase 2 will collect the same longitudinal socio-behavioral, and health survey data on all remaining NH Black and Hispanic parents (Black and Hispanic Supplement, BHS). Additionally, Phase 2 will collect cognitive and DNA data from AHPS Phase 1 and BHS sample parents and their current spouse/partners.

Results

Funded by the National Institute on Aging, recruitment will occur between June 2025 and May 2026, producing an expected total AHPS sample of 5506 parents and their spouse/partners.

Conclusions

The AHPS will be the first longitudinal cohort study powered to address multigenerational racial/ethnic disparities in AD/ADRD risk and protective factors across race/ethnic groups and socioeconomic strata.

Frailty, cognitive impairment, and depressive symptoms in Chinese older adults: an eight-year multi-trajectory analysis

BACKGROUND

Frailty, cognitive impairment, and depressive symptoms are closely interrelated conditions in the aging population. However, limited research has longitudinally analyzed the concurrent trajectories of these three prominent conditions in older adults in China. This study aimed to explore the eight-year trajectories of frailty, cognitive impairment, and depressive symptoms, and to identify individual-level and structural-level factors associated with the trajectories.

METHODS

Four waves of data from the China Health and Retirement Longitudinal Study (2011-2018) were used to identify 6,106 eligible older adults. The main measures included frailty by the frailty index constructed using 30 indicators, cognitive impairment by the summary score of immediate and delayed word recall, figure drawing, serial subtraction, and orientation, and depressive symptoms by the Center for Epidemiologic Studies Depression Scale. Multi-trajectory models identified the trajectories of frailty, cognitive impairment, and depressive symptoms over time. Multinomial logistic regression was employed to estimate the associations between individual-level capital factors and one structural factor (hukou and geographic residency) with the identified trajectories, adjusting for demographic characteristics.

RESULTS

Four trajectories emerged: (1) worsening frailty, worsening cognitive impairment, depression (14.0%); (2) declining pre-frailty, declining cognition, borderline depression (20.0%); (3) pre-frailty, worsening cognitive impairment, no depression (29.3%); and (4) physically robust, declining cognition, no depression (36.7%). Using the "physically robust, declining cognition, no depression" as the reference, not working, no social activity participant, worse childhood family financial situation, and poorer adult health were most strongly associated with the "worsening frailty, worsening cognitive impairment, depression" trajectory; worse health during childhood had the highest association with the "declining pre-frailty, declining cognition, borderline depression" trajectory; less education, lower household consumption, and rural hukou had the greatest association with the increased likelihood of the "pre-frailty, worsening cognitive impairment, no depression" trajectory.

CONCLUSIONS

Findings could inform the understanding of the interrelationship of frailty, cognitive impairment, and depressive symptoms in older adults in China and may help practitioners detect adults at risk for adverse trajectories to implement strategies for proper care.

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.

Low neighborhood deprivation buffers against hippocampal neurodegeneration, white matter hyperintensities, and poorer cognition

There is increasing recognition that socioeconomic inequalities contribute to disparities in brain and cognitive health in older adults. However, whether neighborhood socioeconomic status (SES) buffers individuals with low individual SES against neurodegeneration, cerebrovascular disease, and poorer cognitive function is not well understood. Here, we evaluated whether neighborhood deprivation (Townsend deprivation index) interacted with individual SES (composite household income and education levels) on hippocampus volume, regional cortical thickness, white matter hyperintensities, and cognition in 19,638 individuals (mean age = 54.8) from the UK Biobank. We found that individuals with low individual SES had the smallest hippocampal volumes, greatest white matter hyperintensity burden, and poorest cognition if they were living in high deprivation neighborhoods but that these deleterious effects on brain and cognitive function were attenuated if they were living in low deprivation neighborhoods (p for interactions < .05). While neighborhood deprivation did not interact with individual SES to influence regional cortical thickness, higher neighborhood deprivation was independently associated with lower cortical thickness in 16 regions (false discovery rate q < .05). Across multiple brain indices and cognitive function analyses, we found converging evidence suggesting that low neighborhood deprivation may have a neuroprotective effect against neurodegeneration, cerebrovascular pathology, and cognitive impairment, particularly in vulnerable individuals with low household income and education levels.

Socioeconomic status impacts cognitive and socioemotional processes in healthy ageing

Socioeconomic status (SES) negatively impacts cognitive and executive functioning in older adults, yet its effects on socioemotional abilities have not been studied in this population. Also, evidence on neurocognitive processes associated with ageing primarily comes from Western, educated, industrialized, rich, and democratic (WEIRD) populations, hindering the generalization of findings to persons from upper-middle- and low-middle-income countries, such as those of Latin America. Here, we compared the performance of low- and high-SES older adults from Argentina in cognitive state, executive functions, social cognition (emotion recognition and theory of mind), and counter-empathic social emotions (envy and Schadenfreude; displeasure at others' fortune and pleasure at others' misfortune, respectively). Subsequently, we developed a path analysis to test the relationship among those variables in a theoretically plausible model and tested the main paths via multiple regression analyses. Relative to the high-SES group, low-SES older adults showed poorer performance on all assessed domains. Convergent evidence from covariance analysis, path analysis, and linear regressions suggested that low-SES impact on socioemotional processes was not primary but mediated by cognitive and executive impairment. These findings offer the first characterization of SES impacts on cognitive and socioemotional processes in a non-WEIRD population and have relevant equity-related implications for brain health.