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

Aging, sex, metabolic and life experience factors: Contributions to neuro-inflammaging in Alzheimer's disease research

Alzheimer's disease (AD) is prevalent around the world, yet our understanding of the disease is still very limited. Recent work suggests that the cornerstone of AD may include the inflammation that accompanies it. Failure of a normal pro-inflammatory immune response to resolve may lead to persistent central inflammation that contributes to unsuccessful clearance of amyloid-beta plaques as they form, neuronal death, and ultimately cognitive decline. Individual metabolic, and dietary (lipid) profiles can differentially regulate this inflammatory process with aging, obesity, poor diet, early life stress and other inflammatory factors contributing to a greater risk of developing AD. Here, we integrate evidence for the interface between these factors, and how they contribute to a pro-inflammatory brain milieu. In particular, we discuss the importance of appropriate polyunsaturated fatty acids (PUFA) in the diet for the metabolism of specialised pro-resolving mediators (SPMs); raising the possibility for dietary strategies to improve AD outlook.

Mendelian randomization shows causal effects of birth weight and childhood body mass index on the risk of frailty

Background

The association between birth weight and childhood body mass index (BMI) and frailty has been extensively studied, but it is currently unclear whether this relationship is causal.

Methods

We utilized a two-sample Mendelian randomization (MR) methodology to investigate the causal effects of birth weight and childhood BMI on the risk of frailty. Instrumental variables (p < 5E-08) strongly associated with own birth weight (N = 298,142 infants), offspring birth weight (N = 210,267 mothers), and childhood BMI (N = 39,620) were identified from large-scale genomic data from genome-wide association studies (GWAS). The frailty status was assessed using the frailty index, which was derived from comprehensive geriatric assessments of older adults within the UK Biobank and the TwinGene database (N = 175,226).

Results

Genetically predicted one standard deviation (SD) increase in own birth weight, but not offspring birth weight (maternal-specific), was linked to a decreased frailty index (β per SD increase = -0.068, 95%CI = -0.106 to -0.030, p = 3.92E-04). Conversely, genetically predicted one SD increase in childhood BMI was associated with an elevated frailty index (β per SD increase = 0.080, 95%CI = 0.046 to 0.114, p = 3.43E-06) with good statistical power (99.8%). The findings remained consistent across sensitivity analyses and showed no horizontal pleiotropy (p > 0.05).

Conclusion

This MR study provides evidence supporting a causal relationship between lower birth weight, higher childhood BMI, and an increased risk of frailty.

Midlife cumulative deficit frailty predicts Alzheimer's disease-related plasma biomarkers in older adults

BACKGROUND

The study explores whether frailty at midlife predicts mortality and levels of biomarkers associated with Alzheimer's disease and related dementias (ADRD) and neurodegeneration by early old age. We also examine the heritability of frailty across this age period.

METHODS

Participants were 1,286 community-dwelling men from the Vietnam Era Twin Study of Aging at average ages 56, 62 and 68, all without ADRD at baseline. The cumulative deficit frailty index (FI) comprised 37 items assessing multiple physiological systems. Plasma biomarkers at age 68 included beta-amyloid (Aβ40, Aβ42), total tau (t-tau) and neurofilament light chain (NfL).

RESULTS

Being frail doubled the risk of all-cause mortality by age 68 (OR = 2.44). Age 56 FI significantly predicted age 68 NfL (P = 0.014), Aβ40 (P = 0.001) and Aβ42 (P = 0.023), but not t-tau. Age 62 FI predicted all biomarkers at age 68: NfL (P = 0.023), Aβ40 (P = 0.002), Aβ42 (P = 0.001) and t-tau (P = 0.001). Age 68 FI scores were associated with age 68 levels of NfL (P = 0.027), Aβ40 (P < 0.001), Aβ42 (P = 0.001) and t-tau (P = 0.003). Genetic influences accounted for 45-48% of the variance in frailty and significantly contributed to its stability across 11 years.

CONCLUSIONS

Frailty during one's 50s doubled the risk of mortality by age 68. A mechanism linking frailty and ADRD may be through its associations with biomarkers related to neurodegeneration. Cumulative deficit frailty increases with age but remains moderately heritable across the age range studied. With environmental factors accounting for about half of its variance, early interventions aimed at reducing frailty may help to reduce risk for ADRD.

Frailty and Processing Speed Performance at the Cusp of Midlife in CATSLife

OBJECTIVES

Frailty is not an end state of aging, but rather represents physiological vulnerability across multiple systems that unfolds across adulthood. However, examinations of frailty at the midlife transition, and how frailty may impact other age-sensitive traits, such as processing speed (PS), remain scarce. Our research aims were to examine frailty and frailty-speed associations before midlife, a ripe developmental period for healthy aging interventions.

METHODS

Using data from the Colorado Adoption/Twin Study of Lifespan behavioral development and cognitive aging (N = 1,215; Mage = 33.23 years; standard deviation = 4.98), we constructed 25-item (FI25) and 30-item (FI30) frailty indices. PS was measured using the Colorado Perceptual Speed task and WAIS-III Digit Symbol (DS) subtest. Multilevel models accounted for clustering among siblings and adjusted for sex, race, ethnicity, adoption status, educational attainment, and age.

RESULTS

Reliability of FI measures was apparent from strong intraclass correlations (ICCs) among identical twin siblings, although ICC patterns across all siblings suggested that FI variability may include nonadditive genetic contributions. Higher FI was associated with poorer PS performance but was significant for DS only (BFI25 = -1.17, p = .001, d = -0.12; BFI30 = -1.21, p = .001, d = -0.12). Furthermore, the negative frailty-DS association was moderated by age (BFI25×age = -0.14, p = .042; BFI30×age=-0.19, p = .008) where increasingly worse performance with higher frailty emerged at older ages.

DISCUSSION

Frailty is evident before midlife and associated with poorer PS, an association that magnifies with age. These findings help elucidate the interrelationship between indicators of frailty and cognitive performance for adults approaching midlife, an understudied period within life-span development.

Recent developments in frailty identification, management, risk factors and prevention: A narrative review of leading journals in geriatrics and gerontology

Frailty is an age-related clinical condition characterised by an increased susceptibility to stressors and an elevated risk of adverse outcomes such as mortality. In the light of global population ageing, the prevalence of frailty is expected to soar in coming decades. This narrative review provides critical insights into recent developments and emerging practices in frailty research regarding identification, management, risk factors, and prevention. We searched journals in the top two quartiles of geriatrics and gerontology (from Clarivate Journal Citation Reports) for articles published between 01 January 2018 and 20 December 2022. Several recent developments were identified, including new biomarkers and biomarker panels for frailty screening and diagnosis, using artificial intelligence to identify frailty, and investigating the altered response to medications by older adults with frailty. Other areas with novel developments included exercise (including technology-based exercise), multidimensional interventions, person-centred and integrated care, assistive technologies, analysis of frailty transitions, risk-factors, clinical guidelines, COVID-19, and potential future treatments. This review identified a strong need for the implementation and evaluation of cost-effective, community-based interventions to manage and prevent frailty. Our findings highlight the need to better identify and support older adults with frailty and involve those with frailty in shared decision-making regarding their care.

Translation and validation of the Chinese version of the Japan Frailty Scale

Purpose

Frailty is a difficult-to-measure condition that is susceptible to adverse outcomes. The Japan Frailty Scale (JFS) is a tool for assessing frailty status in older adults. This study aimed to translate and culturally adapt the JFS into a Chinese version (JFS-C).

Materials and methods

The study included 160 older adults as participants. Internal consistency was assessed using Cronbach's alpha, and test-retest reliability was conducted using the intraclass correlation coefficient (ICC). Convergent validity was evaluated by assessing the correlation between JFS-C and the Barthel Index, the Frail scale, and the 36-item Short-Form Health Survey (SF-36). Criterion validity was assessed by comparing JFS-C scores with the Frail scale.

Results

JFS-C demonstrated adequate internal consistency (Cronbach's alphas = 0.711) and excellent test-retest reliability over a 7 to 10-day interval (ICC = 0.949). Correlation analysis showed a strong positive correlation between JFS-C and the Frail scale (r = 0.786, p < 0.001), a moderate negative correlation with the Barthel Index (r = -0.598, p < 0.001), and moderate correlations with various subscales of SF-36 (r = -0.574 to -0.661). However, no significant correlations were found between JFS-C and SF-36 mental health (r = -0.363, p < 0.001) or role emotional (r = -0.350, p < 0.001). Based on the reference standard of the Frail scale phenotype (score ≥ 2), the cutoff value for JFS-C was determined to be 3.

Conclusion

JFS-C demonstrates good reliability and validity in assessing frailty among the older population in China.

Unraveling the metabolic underpinnings of frailty using multicohort observational and Mendelian randomization analyses

Identifying metabolic biomarkers of frailty, an age-related state of physiological decline, is important for understanding its metabolic underpinnings and developing preventive strategies. Here, we systematically examined 168 nuclear magnetic resonance-based metabolomic biomarkers and 32 clinical biomarkers for their associations with frailty. In up to 90,573 UK Biobank participants, we identified 59 biomarkers robustly and independently associated with the frailty index (FI). Of these, 34 associations were replicated in the Swedish TwinGene study (n = 11,025) and the Finnish Health 2000 Survey (n = 6073). Using two-sample Mendelian randomization, we showed that the genetically predicted level of glycoprotein acetyls, an inflammatory marker, was statistically significantly associated with an increased FI (β per SD increase = 0.37%, 95% confidence interval: 0.12-0.61). Creatinine and several lipoprotein lipids were also associated with increased FI, yet their effects were mostly driven by kidney and cardiometabolic diseases, respectively. Our findings provide new insights into the causal effects of metabolites on frailty and highlight the role of chronic inflammation underlying frailty development.

Genetic and Environmental Influences on Longitudinal Frailty Trajectories From Adulthood into Old Age

BACKGROUND

Frailty is a complex, dynamic geriatric condition, but limited evidence has shown how genes and environment may contribute to its longitudinal changes. We sought to investigate sources of individual differences in the longitudinal trajectories of frailty, considering potential selection bias when including a sample of oldest-old twins.

METHODS

Data were from 2 Swedish twin cohort studies: a younger cohort comprising 1 842 adults aged 29-96 years followed up to 15 waves, and an older cohort comprising 654 adults aged ≥79 years followed up to 5 waves. Frailty was measured using the frailty index (FI). Age-based latent growth curve models were used to examine longitudinal trajectories, and extended to a biometric analysis to decompose variability into genetic and environmental etiologies.

RESULTS

A bilinear model with an inflection point at age 75 best described the data, indicating a fourfold to fivefold faster FI increase after 75 years. Twins from the older cohort had significantly higher mean FI at baseline but slower rate of increase afterward. FI level at age 75 was moderately heritable in both men (42%) and women (55%). Genetic influences were relatively stable across age for men and increasing for women, although the most salient amplification in FI variability after age 75 was due to individual-specific environmental influences for both men and women; conclusions were largely consistent when excluding the older cohort.

CONCLUSION

Increased heterogeneity of frailty in late life is mainly attributable to environmental influences, highlighting the importance of targeting environmental risk factors to mitigate frailty in older adults.

The association between chronic heart failure and frailty index: A study based on the National Health and Nutrition Examination Survey from 1999 to 2018

Objective

This study aims to explore the association between the frailty index and chronic heart failure (CHF).

Methods

We collected data from the National Health and Nutrition Examination Survey (NHANES) (1998-2018) database to assess the association between CHF and frailty. Demographic, inquiry, laboratory examinations, and characteristics were gathered to compare CHF and non-CHF groups. Multiple logistic regression analysis was performed to explore the relationship between frailty and CHF. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence interval (CI) for mortality from all causes and cardiovascular disease (CVD).

Results

A total of 16,175 participants with cardiac and cerebrovascular disease were categorized into CHF (n = 1,125) and non-CHF (n = 15,050) groups. In patients with CHF, the prevalence of frailty, pre-frailty, and non-frailty were 66.31, 30.93, and 2.75%, respectively. In multiple logistic regression, patients with CHF who were male (OR = 0.63, 95% CI: 3.11-5.22), whose annual family income was over $20,000 (OR = 0.52, 95% CI: 0.37-0.72, p < 0.001), or with normal hemoglobin level (OR = 0.77, 95% CI: 0.68-0.88, P < 0.001) had a lower likelihood of frailty. CHF patients with hypertension (OR = 3.60, 95% CI: 2.17-5.99, P < 0.0001), coronary heart disease (OR = 1.76, 95% CI: 1.10-2.84, P = 0.02), diabetes mellitus (OR = 1.89, 95% CI: 1.28-2.78, P < 0.001), and stroke (OR = 2.52, 95% CI: 1.53-4.15, P < 0.001) tended to be frail. Survival analysis suggested that pre-frailty and frailty were related to poor all-cause deaths (HR = 1.48, 95% CI: 1.36-1.66; HR = 2.77, 95% CI: 2.40-3.18) and CVD mortality (HR = 1.58, 95% CI: 1.26-1.97; HR = 2.55, 95% CI: 2.02-3.21). CHF patients with frailty were strongly connected with all-cause death (HR = 2.14, 95% CI: 1.27-3.62).

Conclusion

Frailty was positively associated with CHF. Patients with CHF who were male, whose annual family income was over $20,000, or with normal hemoglobin level were negatively correlated to frailty. For patients with cardiac and cerebrovascular disease as well as CHF, frailty was strongly connected with all-cause death.

The impact of household wastewater on the frailty state of the elderly in China: based on a long-term cohort study in China

China's household wastewater discharge has gradually increased, and its composition has become more complex, but the discharge treatment system is not perfect. At present, there is a lack of research on the impact of domestic wastewater on human health, especially on the frailty of the elderly. This study aimed to quantitatively assess the relationship between living wastewater and its main components and the frailty status of the elderly. The research data comes from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), which consists of participants over 60 years old who participated in the three-wave survey in 2008, 2011, and 2014 and combined with domestic wastewater data in the statistical yearbook. A generalized estimating equation (GEE) model was used to assess the link between living wastewater and frailty status in the elderly. The single-pollutant model showed that there was a positive correlation between the discharge of household wastewater and the frailty of the elderly, OR (4.443), 95%CI (3.591, 5.498); ammonia nitrogen had a positive correlation with the frail state of the elderly, OR (4.527), 95%CI (3.587, 5.714); chemical oxygen demand (COD) had a negative association with whether the elderly are frail, OR (0.776), 95%CI (0.609, 0.988). After adjusting for covariates, there was still a positive correlation between household wastewater and the frailty of the elderly, OR (2.792), 95%CI (2.233, 3.492); a positive correlation between ammonia nitrogen and the frail state of the elderly, OR (2.894), 95%CI (2.284, 3.666). The association between COD and the frail state of the elderly, OR (0.823), 95%CI (0.640, 1.058), showed no correlation between the two. The results show that household wastewater may affect the health of the elderly, promote the occurrence of a frail state of the elderly, and increase the medical burden.

Characterization by Gender of Frailty Syndrome in Elderly People according to Frail Trait Scale and Fried Frailty Phenotype

Background: Frailty has emerged as one of the main geriatric syndromes to be prevented in order to improve quality of health and life in the elderly. In this sense, the characterization of this syndrome through reliable and feasible diagnostic tools for clinical use, such as the Frail Trait Scale 5 (FTS-5) and Frail Trait Scale 3 (FTS-3), represents the basis for this objective. Objectives: To characterize the frailty syndrome in a population of older adults using FTS-5, FTS-3, and Fried phenotype (FP) as frailty diagnostic tools. Design: Cross-sectional study. Participants: 300 adults ≥65 years recruited from different Family Health Centers and community groups of older people in Talca, Chile. Methods: The diagnosis of frailty was made according to FP, FTS-5, and FTS-3 tools. Data about sociodemographic characteristics and anthropometric measurements were collected by a clinical interview by a previously trained health professional. Results: A total prevalence of frailty according to the FP of 19.7% was observed; while in the group of women and men it was 21.4% and 15.0%, respectively. Concerning the FTS-5 tool, the total prevalence of frailty was 18%, while in the group of women and men was 18.0% and 17.5%, respectively. The FTS-3 tool shows a total prevalence of frailty of 23.3%, while in the group of women and men a prevalence of 22.7% and 25.0%, respectively. A significant difference is observed with respect to the presence of the Fried criteria of “weakness” (women: 21.4%, men: 38.8%) and “weight loss” (women: 16.8%, men: 7.5%; p < 0.05). A significant difference is observed concerning the average score of “Handgrip” criteria, “walking time”, and “Physical Activity Scale for the Elderly” (PASE) between the group of women and men. Frailty, diagnosed by FTS-3, is significantly associated with the risk factors of overweight (body mass index ≥ 25) (OR: 10.225, 95% CI: 1.297−80.617) and advanced age (age ≥ 75 years) (OR: 1.839, 95% CI: 1.040−3.250). Conclusion: The prevalence of frailty observed with the FTS-5 (18%) and FTS-3 (23.3%) tools are similar to the prevalence observed through the FP (19.7%) and those reported in other observational studies. Considering the similar prevalence of frailty diagnosed with the three tools, FTS-3 should be a valuable tool for the screening of frailty in the community.

Frailty and Associated Factors among Chinese Centenarians

OBJECTIVES

The study aimed to apply the frailty index (FI) to assess frailty status among Chinese centenarians and analyse its associated factors.

DESIGN

The study was a cross-sectional study.

SETTING AND PARTICIPANTS

The study included 1043 centenarians (742 females and 301 males) aged ≥100 years from the 2018 wave of the China Longitudinal Healthy Longevity Survey.

MEASUREMENTS

All participants were assessed for frailty by the FI. Basic characteristics, including age, height, weight, calf circumference, waist circumference, hip circumference, sex, years of education, financial status, exercise, fall status, coresidence, smoking, alcohol consumption, number of natural teeth, denture use, toothache, and tooth brushing, were collected. Multivariate logistic regression was used to analyse the associations between risk factors and frailty.

RESULTS

The average age of the participants was 102.06±2.55 years (range: 100-117 years). The FI ranged between 0.00 and 0.63. The mean FI for all participants was 0.27±0.13 (median 0.25; interquartile range 0.20-0.35). Participants were divided into quartiles. The number of natural teeth and denture use, coresidence, sex, exercise, and financial status showed significant associations with frailty classes (all P<0.05). Multivariate logistic regression analysis indicated that having ≤20 natural teeth without dentures (OR, 95% CI= 1.89(0.004-1.246), P<0.05), having ≤20 natural teeth with dentures (OR, 95% CI=2.21(0.158,1.432), P=0.015), living alone or in an institution (OR, 95% CI=1.68(0.182-0.849), P=0.002), lacking exercise (OR, 95% CI=2.54(0.616-1.246), P<0.001), having insufficient financial resources (OR, 95% CI=2.9(0.664-1.468), P<0.001), and being female (OR, 95% CI=1.47(0.137,0.634), P=0.002) were independent risk factors for frailty.

CONCLUSION

Chinese centenarian women are frailer than men. Having fewer natural teeth, living alone or in an institution, lacking exercise, and having insufficient financial resources were the factors associated with frailty among Chinese centenarians. Family conditions and healthy lifestyles may be important for frailty status in centenarians.

Frailty and the risk of dementia: is the association explained by shared environmental and genetic factors?

BACKGROUND

Frailty has been identified as a risk factor for cognitive impairment and dementia. However, it is not known whether familial factors, such as genetics and shared environmental factors, underlie this association. We analyzed the association between frailty and the risk of dementia in a large twin cohort and examined the role of familial factors in the association.

METHODS

The Rockwood frailty index (FI) based on 44 health deficits was used to assess frailty. The population-level association between FI and the risk of all-cause dementia was analyzed in 41,550 participants of the Screening Across the Lifespan Twin (SALT) study (full sample, aged 41-97 years at baseline), using Cox and competing risk models. A subsample of 10,487 SALT participants aged 65 and older who received a cognitive assessment (cognitive sample) was used in a sensitivity analysis to assess the effect of baseline cognitive level on the FI-dementia association. To analyze the influence of familial effects on the FI-dementia association, a within-pair analysis was performed. The within-pair model was also used to assess whether the risk conferred by frailty varies by age at FI assessment.

RESULTS

A total of 3183 individuals were diagnosed with dementia during the 19-year follow-up. A 10% increase in FI was associated with an increased risk of dementia (hazard ratio [HR] 1.17 (95% confidence interval [CI] 1.07, 1.18)) in the full sample adjusted for age, sex, education, and tobacco use. A significant association was likewise found in the cognitive sample, with an HR of 1.13 (95% CI 1.09, 1.20), adjusted for age, sex, and cognitive level at baseline. The associations were not attenuated when adjusted for APOE ɛ4 carrier status or considering the competing risk of death. After adjusting for familial effects, we found no evidence for statistically significant attenuation of the effect. The risk conferred by higher FI on dementia was constant after age 50 until very old age.

CONCLUSIONS

A higher level of frailty predicts the risk of dementia and the association appears independent of familial factors. Targeting frailty might thus contribute to preventing or delaying dementia.