Genes Related to Education Predict Frailty Among Older Adults in the United States

Spousal education and frailty levels among Chinese older adults: A national longitudinal study

Background

Prior research has identified one's own education level as a risk factor for frailty. However, the association between spousal education and frailty in later life is uncertain. We aim to examine the longitudinal association between spousal education and frailty levels among Chinese older populations.

Methods

3856 participants aged 60 and older from the 2011-2018 China Health and Retirement Longitudinal Study were analyzed. A 54-item deficit cumulative frailty index was developed to evaluate frailty levels at each follow-up. Linear mixed-effects models were used to examine the longitudinal association of spousal education with frailty levels, and whether this association varied by sex and own education level.

Results

Higher spouse education was associated with lower frailty levels, and this association decreased with age. Compared with older adults whose spouses had no formal education, older adults whose spouses had less than middle school education had an 8.82 lower level of frailty (95% CI: 15.05 to -2.58, P < 0.01); those with spouses with middle school education and above had a 23.44 lower level (95% CI: 31.43 to -15.44, P < 0.001). Stratified analysis showed that every additional year of spouse education was also associated with lower frailty levels in non-frail participants at baseline, but stronger among those already frail. The association between high spousal education and lower frailty did not vary by sex or own education.

Conclusion

This study reveals a significant association between having a more educated spouse and lower later-life frailty levels for both older men and women, regardless of one's own educational background. It emphasizes the importance of leveraging educated spouses to prevent and manage frailty.

Genetic endowments for social capital: An investigation accounting for genetic nurturing effects

Despite social capital having been shown to be important for health and well-being, relatively little research has examined genetic determinants. Genetic endowments for education have been shown to influence human, financial, and health capital, but few studies have examined social capital, and those conducted have yet to account for genetic nurturing. We used the Add-Health data to study the effect of genetic endowments on individual social capital using the education polygenic score (PGS). We used sibling fixed effects models and controlled for the family environment to account for genetic nurturing. After accounting for the family environment, we found moderately large significant associations between the education PGS and volunteering, but associations with religious service attendance and number of friends were completely attenuated in sibling fixed effects models. These findings highlight that genetic endowments play an important role in influencing volunteering and the importance of accounting for genetic nurturing.

Associations between modifiable risk factors and frailty: a Mendelian randomisation study

BACKGROUND

Early identification of modifiable risk factors is essential for the prevention of frailty. This study aimed to explore the causal relationships between a spectrum of genetically predicted risk factors and frailty.

METHODS

Univariable and multivariable Mendelian randomisation (MR) analyses were performed to explore the relationships between 22 potential risk factors and frailty, using summary genome-wide association statistics. Frailty was accessed by the frailty index.

RESULTS

Genetic liability to coronary artery disease (CAD), type 2 diabetes mellitus (T2DM), ischaemic stroke, atrial fibrillation and regular smoking history, as well as genetically predicted 1-SD increase in body mass index, systolic blood pressure, diastolic blood pressure, low-density lipoprotein cholesterol, triglycerides, alcohol intake frequency and sleeplessness were significantly associated with increased risk of frailty (all p<0.001). In addition, there was a significant inverse association between genetically predicted college or university degree with risk of frailty (beta -0.474; 95% CI (-0.561 to -0.388); p<0.001), and a suggestive inverse association between high-density lipoprotein cholesterol level with risk of frailty (beta -0.032; 95% CI (-0.055 to -0.010); p=0.004). However, no significant causal associations were observed between coffee consumption, tea consumption, serum level of total testosterone, oestradiol, 25-hydroxyvitamin D, C reactive protein or moderate to vigorous physical activity level with frailty (all p>0.05). Results of the reverse directional MR suggested bidirectional causal associations between T2DM and CAD with frailty.

CONCLUSIONS

This study provided genetic evidence for the causal associations between several modifiable risk factors with lifetime frailty risk. A multidimensional approach targeting these factors may hold a promising prospect for prevention frailty.

Marital transitions and frailty among middle-aged and older adults in China: The roles of social support

Background

This study explored the association of marital transitions and frailty among Chinese middle-aged and older people and whether this association differs by social support.

Methods

We used a sample of 12,388 adults aged ≥45 years who participated in the China Health and Retirement Longitudinal Study (CHARLS) between 2015 and 2018. Between-wave changes in marital status ("married at both times", "unmarried to married", "married to unmarried", "unmarried at both times") were used to explore the changes in frailty measured by the frailty index (FI), which was constructed from 55 health variables. Social support was evaluated based on social engagement and intergenerational support. The associations among marital transitions, social support and frailty were analyzed using generalized estimating equations (GEEs).

Results

The mean FI of 12,388 participants was 0.23 (SD = 0.13). Participants who were married to unmarried (β = 0.014, B = 0.005, P = 0.012) and unmarried at both times (β = 0.022, B = 0.003, P < 0.001) had significant a positive impact on FI compared with participants who were married at both times. Social engagement, financial support by children and providing care to grandchildren had an interactive effect with marital transitions in influencing FI.

Conclusions

Being unmarried may increase frailty among Chinese middle-aged and older adults. Financial support by children may mitigate the adverse effects of being unmarried on frailty.

Cross-National and Cross-Generational Evidence That Educational Attainment May Slow the Pace of Aging in European-Descent Individuals

OBJECTIVES

Individuals with more education are at lower risk of developing multiple, different age-related diseases than their less-educated peers. A reason for this might be that individuals with more education age slower. There are 2 complications in testing this hypothesis. First, there exists no definitive measure of biological aging. Second, shared genetic factors contribute toward both lower educational attainment and the development of age-related diseases. Here, we tested whether the protective effect of educational attainment was associated with the pace of aging after accounting for genetic factors.

METHODS

We examined data from 5 studies together totaling almost 17,000 individuals with European ancestry born in different countries during different historical periods, ranging in age from 16 to 98 years old. To assess the pace of aging, we used DunedinPACE, a DNA methylation algorithm that reflects an individual's rate of aging and predicts age-related decline and Alzheimer's disease and related disorders. To assess genetic factors related to education, we created a polygenic score based on the results of a genome-wide association study of educational attainment.

RESULTS

Across the 5 studies, and across the life span, higher educational attainment was associated with a slower pace of aging even after accounting for genetic factors (meta-analysis effect size = -0.20; 95% confidence interval [CI]: -0.30 to -0.10; p = .006). Further, this effect persisted after taking into account tobacco smoking (meta-analysis effect size = -0.13; 95% CI: -0.21 to -0.05; p = .01).

DISCUSSION

These results indicate that higher levels of education have positive effects on the pace of aging, and that the benefits can be realized irrespective of individuals' genetics.

Perceived Decisional Control as a Mediator between Moving to Assisted Living Due to Caregiver Burden and Relocation Adjustment

OBJECTIVES

The rapid growth of the older population in the United States has led to increased utilization of assisted living facilities (ALFs), and it is important to understand what factors may facilitate better adjustment. This study examined the mediating role of perceived decisional control in the relationship between moving to assisted living (AL) to prevent/alleviate caregiver burden and post-relocation adjustment.

METHODS

Participants were 91 newly-transitioned residents of ALFs in Alabama and Maryland. Data were gathered through in-person interviews and questionnaires. Mediation analyses were done using the PROCESS macro for SPSS, applying 5,000 bootstrap resamples with 95% bias-corrected confidence intervals estimated around the indirect effect.

RESULTS

The effect of moving to AL to prevent/alleviate caregiver burden on post-relocation depression and socialization was indirect and dependent on the degree of perceived decisional control.

CONCLUSIONS

Perceived decisional control may be a key factor in adjusting to AL, even when the move is catalyzed by such a complex and emotionally laden construct as caregiver burden.

CLINICAL IMPLICATIONS

Greater perceived decisional control over potential relocation may facilitate better adjustment, and other parties involved in the decision-making process should strive to involve the older adult in question in this process to the greatest extent possible.

Genetic, Social, and Lifestyle Drivers of Healthy Aging and Longevity

Purpose of Review

"Healthy aging" is the state of the aging process in which a person can maintain physical, social, mental, and spiritual wellness. This literature review presents an overview of recent studies that explore how biological, social, and environmental factors contribute to healthy aging.

Recent Findings

A number of genome-wide association studies have been conducted recently for traits related to healthy aging, such as frailty index, healthspan, muscle strength, and parental longevity, leading to the discovery of dozens of genetic variants associated with these traits. In parallel, associations between healthy aging measures and multiple non-biological environmental elements have been identified as key moderators of the aging process, indirectly influencing day-to-day homeostatic processes.

Summary

Individual variations in lifespan and healthspan are influenced by genetic factors, with a heritability of ~ 25% in developed countries. Non-genetic risk variance is explained in part by social, cultural, and lifestyle conditions. Altogether, these factors contribute to a multifaceted state of wellness over time, shaping individual risk to frailty and resilience during the aging process. Notably, "Blue Zone" populations, which are characterized by an abundance in healthy lifestyles across generations, share some commonalities regarding determinants of health.

Polygenic prediction of educational attainment within and between families from genome-wide association analyses in 3 million individuals

We conduct a genome-wide association study (GWAS) of educational attainment (EA) in a sample of ~3 million individuals and identify 3,952 approximately uncorrelated genome-wide-significant single-nucleotide polymorphisms (SNPs). A genome-wide polygenic predictor, or polygenic index (PGI), explains 12-16% of EA variance and contributes to risk prediction for ten diseases. Direct effects (i.e., controlling for parental PGIs) explain roughly half the PGI's magnitude of association with EA and other phenotypes. The correlation between mate-pair PGIs is far too large to be consistent with phenotypic assortment alone, implying additional assortment on PGI-associated factors. In an additional GWAS of dominance deviations from the additive model, we identify no genome-wide-significant SNPs, and a separate X-chromosome additive GWAS identifies 57.

Frailty in younger-old and oldest-old adults in a context of high social vulnerability

Objective: To analyze the factors associated with physical frailty in community-dwelling younger-old (60 to 74 years) and oldest-old (75 years or older) adults in a region of high social vulnerability. Social vulnerability refers to the absence of or difficulty obtaining social support from public institutions, situations that hinder the realization of or deny citizens their social rights and affect their social cohesion, and the ability to react to high-risk social situations – associated health and illness. In this study, we used the São Paulo Social Vulnerability Index developed by the SEADE Foundation, which classifies social vulnerability based on socioeconomic and demographic conditions. Methods: Quantitative analytical study of 303 older adults. Fried frailty phenotype assessment was performed and the Mini Mental State Examination, Geriatric Depression Scale, Katz Index of Independence in Activities of Daily Living, and the Lawton Scale of Instrumental Activities of Daily Living were administered. Descriptive statistics and logistic regression were used to analyze data. Results: Of the older adults, 12.21% were nonfrail, 60.72% were prefrail, and 27.06% were frail. The single factor most associated with frailty was depressive symptoms (OR = 2.65; 95%CI 1.38 – 5.08) in the younger-old and illiteracy (OR = 14.64; 95%CI 1.82 – 116.51) in the oldest old. Conclusion: The factor most associated with frailty in younger-old adults (aged 60 to 74 years) was depressive symptoms, whereas in the oldest old (aged 75 or older), the factor most associated with frailty was being illiterate. The results of this investigation should prompt health professionals and managers to discuss and program new strategies for health promotion and prevention of factors that may aggravate frailty, respecting the differences found between older adults in early and later old age.

Sex differences in genetic and environmental influences on frailty and its relation to body mass index and education

Frailty is influenced by numerous genetic and environmental factors. However, sex differences in how these factors affect frailty, and the gene-environment interplay among frailty and two of its well-established risk factors, unhealthy body mass index (BMI) and low education, are less clear. In a large sample of 42,994 Swedish twins, we used structural equation models to estimate the genetic (heritability) and environmental sources of variance in frailty, defined as the frailty index (FI), separately in men and women. Genetic and individual-specific environmental factors contributed approximately equally to the FI variance. The heritability of FI was slightly, but significantly, higher in women (52%) than in men (45%), yet we found only weak-to-no indication of different sources of genetic variance influencing frailty across sexes. We observed a small-to-moderate genetic overlap between FI and BMI, and that the correlation between FI and education was largely explained by environmental factors common to twins in a pair. Additionally, genetic factors accounted for more of FI variation at both low and high BMI levels, with similar patterns in both sexes. In conclusion, the twin-based heritability of frailty is higher in women than in men, and different mechanisms may underlie the associations of frailty with BMI and education.

A mutation associated with stress resistance in mice is associated with human grip strength and mortality

Hand grip strength (GS) is a valid and reliable predictor of future morbidity and mortality and is considered a useful indicator of aging. In this paper, we use results from the genetic analysis in animal studies to evaluate associations for GS, frailty, and subsequent mortality among humans. Specifically, we use data from the Health and Retirement Survey (HRS) to investigate the association between three polymorphisms in a candidate frailty gene (Tiam1) and GS. Results suggest that the A allele in rs724561 significantly reduces GS among older adults in the US (b = -0.340; p < .006) and is significantly associated with self-reported weakness (b = 0.221; p = .036). This same polymorphism was weakly associated (one-tailed) with an increased risk of mortality (b = 1.091; p < .093) and adjustments for GS rendered this association statistically non-significant (b = 1.048; p < .361). Overall, our results provide tentative evidence that the Tiam1 gene may be associated with frailty development, but we encourage further studies.

Genetics of frailty: A longevity perspective

Frailty is a complex late life phenotype characterized by cumulative declines in multiple physiological systems that increases the risk for disability and mortality. The biological changes associated with aging are risk factors for frailty as well as for complex diseases; whereas longevity is assumed to be an outcome of protective biological mechanisms. Understanding the interplay between biological alterations associated with aging and protective mechanisms associated with longevity in the context of frailty may help guide development of interventions to increase healthspan and promote successful aging. The complexity of these phenotypes and relatively low heritability in studies are the main roadblocks in deciphering genetic mechanisms of these age associated conditions. We review genetic research related to frailty, and discuss the possible intertwined biology of frailty and longevity.