Life Course Socioeconomic Disadvantage and the Aging Immune System: Findings From the Health and Retirement Study

The association between incarceration and housing insecurity and advanced immune age during late life

Emerging evidence suggests that psychosocial stress ages the immune system. Accordingly, immune aging may be an important potential mechanism linking psychosocial stress to aging-related decline and disease. Incarceration and housing insecurity represent severe and complex experiences of a multitude of psychosocial stressors, including discrimination, violence, and poverty. In this study, we investigated the association between incarceration and/or housing insecurity and advanced immune age in adults aged 55 and older. Our sample was derived from the Health and Retirement Survey (HRS), with n = 7003 individuals with valid housing insecurity data and n = 7523 with valid incarceration data. From 2016 Venous Blood Study data, we assessed immune aging using a comprehensive set of immune markers including inflammatory markers (IL-6, CRP, s-TNFR1), markers of viral control (CMV IgG antibodies), and ratios of T cell phenotypes (CD8+:CD4+, CD+ Memory: Naïve, CD4+ Memory: Naïve, CD8+ Memory: Naïve ratios). We found that both incarceration and housing insecurity were strongly associated with more advanced immune aging as indicated by increased inflammation, reduced viral control, and reduction in naïve T cells relative to memory T cells. Given that those who experienced incarceration, housing insecurity, and/or are racialized minorities were less likely to be included in this study, our results likely underestimated these associations. Despite these limitations, our study provided strong evidence that experiencing incarceration and/or housing insecurity may accelerate the aging of the immune system.

Socioeconomic status is negatively associated with immunosenescence but positively associated with inflammation among middle-aged women in Cebu, Philippines

BACKGROUND

Socioeconomic status (SES) gradients in health are well-documented, and while biological pathways are incompletely understood, chronic inflammation and accelerated immune aging (immunosenescence) among lower SES individuals have been implicated. However, previous findings have come from samples in higher income countries, and it is unclear how generalizable they are to lower- and middle-income countries (LMIC) with different infectious exposures and where adiposity-an important contributor to chronic inflammation-might show different SES patterning. To address this gap, we explored associations between SES and inflammation and immunosenescence in a sample of women in Cebu, Philippines.

METHODS

Data came from the mothers of the Cebu Longitudinal Health and Nutrition Survey birth cohort (mean age: 47.7, range: 35-69 years). SES was measured as a combination of annual household income, education level, and assets. Chronic inflammation was measured using C-reactive protein (CRP) in plasma samples from 1,834 women. Immunosenescence was measured by the abundance of exhausted CD8T (CD8 + CD28-CD45RA-) and naïve CD8T and CD4T cells, estimated from DNA methylation in whole blood in a random subsample of 1,028. Possible mediators included waist circumference and a collection of proxy measures of pathogen exposure.

RESULTS

SES was negatively associated with the measures of immunosenescence, with slight evidence for mediation by a proxy measure for pathogen exposure from the household's drinking water source. In contrast, SES was positively associated with CRP, which was explained by the positive association with waist circumference.

CONCLUSIONS

Similar to higher income populations, in Cebu there is an SES-gradient in pathogen exposures and immunosenescence. However, lifestyle changes occurring more rapidly among higher SES individuals is contributing to a positive association between SES and adiposity and inflammation. Our results suggest more studies are needed to clarify the relationship between SES and inflammation and immunosenescence across LMIC.

Peripheral immune function and Alzheimer's disease: a living systematic review and critical appraisal

BACKGROUND

A growing body of literature examines the relationship between peripheral immune function and Alzheimer's Disease (AD) in human populations. Our living systematic review summarizes the characteristics and findings of these studies, appraises their quality, and formulates recommendations for future research.

METHODS

We searched the electronic databases PubMed, PsycINFO, and Web of Science, and reviewed references of previous reviews and meta-analyses to identify human studies examining the relationship between any peripheral immune biomarkers and AD up to September 7th, 2023. We examined patterns of reported statistical associations (positive, negative, and null) between each biomarker and AD across studies. Evidence for each biomarker was categorized into four groups based on the proportion of studies reporting different associations: corroborating a positive association with AD, a negative association, a null association, and presenting contradictory findings. A modified Newcastle-Ottawa scale (NOS) was employed to assess the quality of the included studies.

FINDINGS

In total, 286 studies were included in this review. The majority were cross-sectional (n = 245, 85.7%) and hospital-based (n = 248, 86.7%), examining relationships between 187 different peripheral immune biomarkers and AD. Cytokines were the most frequently studied group of peripheral immune biomarkers. Evidence supported a positive association with AD for six biomarkers, including IL-6, IL-1β, IFN-γ, ACT, IL-18, and IL-12, and a negative association for two biomarkers, including lymphocytes and IL-6R. Only a small proportion of included studies (n = 22, 7.7%) were deemed to be of high quality based on quality assessment.

INTERPRETATION

Existing research on peripheral immune function and AD exhibits substantial methodological variations and limitations, with a notable lack of longitudinal, population-based studies investigating a broad range of biomarkers with prospective AD outcomes. The extent and manner in which peripheral immune function can contribute to AD pathophysiology remain open questions. Given the biomarkers that we identified to be associated with AD, we posit that targeting peripheral immune dysregulation may present a promising intervention point to reduce the burden of AD.

Chronic Stress and Latent Virus Reactivation: Effects on Immune Aging, Chronic Disease Morbidity, and Mortality

OBJECTIVES

Social stress has been shown to affect immune functioning. Past research has found that chronic social stress and latent viral infections accelerate immune aging, leading to chronic disease morbidity and mortality. Chronic stress may also reactivate latent viral infections, like cytomegalovirus (CMV), accelerating the aging of the immune system.

METHOD

Utilizing panel survey data from 8,995 U.S. adults aged 56 or older from the Health and Retirement Study, this study investigates whether chronic stress interacts with CMV positivity to drive aging of the immune system, multimorbidity, and mortality.

RESULTS

Results of moderated mediation analysis indicate that the effect of CMV positivity on morbidity and mortality as mediated by immune aging indicators is amplified by chronic stress.

DISCUSSION

These findings suggest that immune aging is a biological pathway underlying the stress process and help explain past findings in the literature on stress and health.

Socioeconomic and race/ethnic differences in immunosenescence: Evidence from the Health and Retirement Study

BACKGROUND

The COVID-19 pandemic has highlighted the urgent need to understand variation in immunosenescence at the population-level. Thus far, population patterns of immunosenescence have not well described.

METHODS

We characterized measures of immunosenescence from the 2016 Venous Blood Study from the nationally representative U.S Health and Retirement Study (HRS) of individuals ages 50 years and older.

RESULTS

Median values of the CD8+:CD4+, EMRA:Naïve CD4+ and EMRA:Naïve CD8+ ratios were higher among older participants and were lower in those with additional educational attainment. Generally, minoritized race and ethnic groups had immune markers suggestive of a more aged immune profile: Hispanics had a CD8+:CD4+ median value of 0.37 (95 % CI: 0.35, 0.39) compared to 0.30 in non-Hispanic Whites (95 % CI: 0.29, 0.31). Non-Hispanic Blacks had the highest median value of the EMRA:Naïve CD4+ ratio (0.08; 95 % CI: 0.07, 0.09) compared to non-Hispanic Whites (0.03; 95 % CI: 0.028, 0.033). In regression analyses, race/ethnicity and education were associated with large differences in the immune ratio measures after adjustment for age and sex.

CONCLUSIONS

Lower educational attainment and minoritized racial ethnic status were associated with higher levels of immunosenescence. This population variation may have important implications for both risk of age-related disease and vulnerability to emerging pathogens (e.g., SARS-CoV-2).

The Validity and Reliability of Retrospective Measures of Childhood Socioeconomic Status in the Health and Retirement Study: Evidence From the 1940 U.S. Census

OBJECTIVES

Retrospective measures of childhood socioeconomic status (SES) in cohort studies of aging that first observe people late in life-such as the Health and Retirement Study (HRS)-are widely used. However, their measurement validity and reliability are unknown. We assess the reliability and validity of the HRS's retrospective measures of parental education and childhood family finances.

METHODS

We use records for 6,343 HRS sample members who were children in 1940 that have been linked to records from the complete-count 1940 U.S. Census. We assess interrater reliability by comparing (a) retrospective reports of childhood SES collected from sample members in the 1992-2018 HRS to (b) prospective measures of parallel concepts collected from HRS sample members' parents in the 1940 Census. We assess predictive validity by comparing the results of analyses that model later-life outcomes as a function of childhood SES as measured both prospectively and retrospectively.

RESULTS

Interrater reliabilities of retrospective measures of parental education are high; however, the same is not true of the retrospective measure of childhood family finances. Both retrospective and prospective measures of childhood SES are predictive of later-life outcomes, and with similar strengths and directions of associations for most outcomes.

DISCUSSION

Researchers who rely on retrospective indicators of childhood SES from the HRS should be aware of their measurement properties. They are measured with error, and that error modestly attenuates estimates of their associations with later-life outcomes. However, prospective and retrospective measures of childhood SES have similar predictive validity. These findings should reassure researchers who rely on retrospective measures of childhood SES in the HRS and similarly designed surveys.

Association of life-course socioeconomic status with allostatic load in Chinese middle-aged and older adults

AIM

To examine the association of life-course socioeconomic status (SES) and mobility with allostatic load (AL) in a large cohort of Chinese middle-aged and older adults.

METHODS

Drawing on data from 17 552 middle-aged and older adults from three waves of a longitudinal study conducted in China in 2011-2015, generalized estimating equation (GEE) models were used for the overall sample and subsample to examine the association between life-course SES and AL.

RESULTS

On the whole, those who were literate had lower AL (β = -0.034, 95% CI = -0.065, -0.004), while those with a non-agricultural occupation (β = 0.093, 95% CI = 0.065, 0.120) and better financial status in childhood (β = 0.037, 95% CI = 0.012, 0.063) or adulthood (β = 0.033, 95% CI = 0.009, 0.058) had higher AL. In terms of SES mobility, a stable high education was associated with lower AL (β = -0.041, 95% CI = -0.078, -0.004). Upward (β = 0.090, 95% CI = 0.061, 0.120) or stable high (β = 0.075, 95% CI = 0.025, 0.125) occupation was related to higher AL. Downward (β = 0.034, 95% CI = 0.003, 0.064) or stable high (β = 0.072, 95% CI = 0.037, 0.107) financial status was associated with higher AL. Education manifested no associations with AL for the rural and men samples. Financial status showed no relationship with AL for the urban sample.

CONCLUSIONS

Our findings demonstrate the importance of applying life-course models for gaining an understanding of SES and AL. Efforts to lower AL among Chinese middle-aged and older adults should consider childhood and current SES status, as well as different subgroups. Geriatr Gerontol Int 2022; 22: 425-432.

Sociodemographic Differences in Population-Level Immunosenescence in Older Age

Background

The COVID-19 pandemic has highlighted the urgent need to understand variation in immunosenescence at the population-level. Thus far, population patterns of immunosenescence are not well described.

Methods

We characterized measures of immunosenescence from newly released venous blood data from the nationally representative U.S Health and Retirement Study (HRS) of individuals ages 56 years and older.

Findings

Median values of the CD8+:CD4+, EMRA:Nave CD4+ and EMRA:Nave CD8+ ratios were higher among older participants and were lower in those with additional educational attainment. Generally, minoritized race and ethnic groups had immune markers suggestive of a more aged immune profile: Hispanics had a CD8+:CD4+ median value of 0.37 (95% CI: 0.35, 0.39) compared to 0.30 in Whites (95% CI: 0.29, 0.31). Blacks had the highest median value of the EMRA:Nave CD4+ ratio (0.08; 95% CI: 0.07, 0.09) compared to Whites (0.03; 95% CI: 0.028, 0.033). In regression analyses, race/ethnicity and education were associated with large differences in the immune ratio measures after adjustment for age and sex. For example, each additional level of education was associated with roughly an additional decade of immunological age, and the racial/ethnic differences were associated with two to four decades of additional immunological age.

Interpretation

Our study provides novel insights into population variation in immunosenescence. This has implications for both risk of age-related disease and vulnerability to novel pathogens (e.g., SARS-CoV-2).

Funding

This study was partially funded by the U.S. National Institutes of Health, National Institute on Aging R00AG062749. AEA and GAN acknowledge support from the National Institutes of Health, National Institute on Aging R01AG075719. JBD acknowledges support from the Leverhulme Trust (Centre Grant) and the European Research Council grant ERC-2021-CoG-101002587.

Research in context

Evidence before this study: Alterations in immunity with chronological aging have been consistently demonstrated across human populations. Some of the hallmark changes in adaptive immunity associated with aging, termed immunosenescence, include a decrease in nave T-cells, an increase in terminal effector memory cells, and an inverted CD8:CD4 T cell ratio. Several studies have shown that social and psychosocial exposures can alter aspects of immunity and lead to increased susceptibility to infectious diseases.Add value of this study: While chronological age is known to impact immunosenescence, there are no studies examining whether social and demographic factors independently impact immunosenescence. This is important because immunosenescence has been associated with greater susceptibility to disease and lower immune response to vaccination. Identifying social and demographic variability in immunosenescence could help inform risk and surveillance efforts for preventing disease in older age. To our knowledge, we present one of the first large-scale population-based investigations of the social and demographic patterns of immunosenescence among individuals ages 50 and older living in the US. We found differences in the measures of immunosenescence by age, sex, race/ethnicity, and education, though the magnitude of these differences varied across immune measures and sociodemographic subgroup. Those occupying more disadvantaged societal positions (i.e., minoritized race and ethnic groups and individuals with lower educational attainment) experience greater levels of immunosenescence compared to those in less disadvantaged positions. Of note, the magnitude of effect of sociodemographic factors was larger than chronological age for many of the associations.Implications for practice or policy and future research: The COVID-19 pandemic has highlighted the need to better understand variation in adaptive and innate immunity at the population-level. While chronological age has traditionally been thought of as the primary driver of immunological aging, the magnitude of differences we observed by sociodemographic factors suggests an important role for the social environment in the aging human immune system.

The Association Between Cytomegalovirus and Disability by Race/Ethnicity and Sex: Results From the Health and Retirement Study

Recent studies have documented a decline in the overall prevalence of disability in the United States; however, racial/ethnic and sex disparities continue to persist. Cytomegalovirus (CMV) infection, a socially patterned exposure, may be a key mechanism in understanding these previously documented disparities. Using data from a nationally representative study, the 2016 Health and Retirement Study, we employed Poisson log-binomial models to estimate the prevalence of disability in a comparison of CMV-seropositive and -seronegative adults and investigated effect modification by race/ethnicity and sex. Among the 9,029 participants (55% women; mean age = 67.4 years), 63% were CMV-seropositive and 15% were disabled. CMV seropositivity was highest among non-Hispanic Black (88%) and Hispanic (92%) adults as compared with non-Hispanic White adults (57%). We found evidence for effect modification in the association between CMV and disability by sex but not race/ethnicity. While the 95% confidence intervals in the fully adjusted models included the null value, in comparison with seronegative women, our results suggest a greater prevalence of disability among CMV-seropositive women (prevalence ratio = 1.16, 95% confidence interval: 0.97, 1.38) but not among men (prevalence ratio = 0.85, 95% confidence interval: 0.69, 1.06). Results provide initial support for the hypothesis that CMV may be an important determinant of sex disparities in disability.