Frailty and telomere length: Cross-sectional analysis in 3537 older adults from the ESTHER cohort

Understanding physical aging in relation to biological aging, telomere length: A systematic review

BACKGROUND

Telomere length (TL) serves as a marker for biological aging, influenced by chronological aging but distinct from it. This systematic review aims to synthesize the evidence on the associations between components of physical aging and TL in the elderly population.

METHODS

A comprehensive search was conducted in online databases of PubMed, Web of Science, ProQuest, and ScienceDirect to identify the eligible papers published until 1st August 2024. The authors independently extracted data using the standardized form. The quality of the included studies was evaluated for the risks of biases.

RESULTS

A total of 1080 records were initially identified using the predefined search strategy. A total of 40 eligible records were included in this review. When assessing physical aging, the nature and type of measurements across studies vary, including subjective, objective, and a combination of both approaches. Subjective assessments of general health or physical limitations may be linked with TL, while frailty, whether measured subjectively or objectively, shows associations with TL in less than 35 percent of total studies. In contrast, composite measures of physical performance/ability are consistently associated with TL in the elderly population.

CONCLUSIONS

In conclusion, we demonstrated that the associations between physical aging and TL varies depending on the type and nature of physical aging assessments. Composite measures of physical performance/ability demonstrate a strong and consistent parameter of physical aging to link with TL. Future research should prioritize standardized, multidimensional approaches to measure physical aging to understand better its association with TL to support healthy aging strategies.

Frailty in lung transplant recipients is associated with anemia and telomere dysfunction but independent of epigenetic age

Frailty is a syndrome of vulnerability to stressors linked to worse outcomes before and after lung transplantation. However, the biological basis of this association is unknown. Biological correlates of aging include epigenetic reprograming, chronic inflammation, telomere dysfunction, and anemia. We hypothesized that these aging-associated biological processes would be associated with frailty in lung transplant recipients. In a nested case-control study, we compared 43 lung transplant recipients who were frail pretransplant and posttransplant with 43 nonfrail matched controls. We quantified peripheral blood leukocyte epigenetic aging (Horvath) and longevity (GrimAge) clocks, telomere length, cytokine profiles, and hemoglobin before transplant. Epigenetic clocks were correlated with age but not frailty. However, we observed hypermethylation of multiple gene pathways, including hedgehog signaling and angiogenesis, and associated decreased levels of plasma cytokines in frail recipients. Frailty was also associated with telomere dysfunction and anemia. Overall, telomere dysfunction and anemia of chronic disease were most linked to frailty in this cohort, whereas epigenetic aging and chronic inflammation were not. Understanding the heterogeneity of aging syndromes may help target interventions in frail lung transplant recipients.

Yoga Practice as a Potential Sarcopenia Prevention Strategy in Indonesian Older Adults: A Cross-Sectional Study

Background

Sarcopenia is characterized by the progressive loss of skeletal muscle mass and poses a significant health challenge for older adults by increasing the risk of disability and decreasing quality of life. Yoga considers as a low-risk and beneficial exercise for older adults. This research aims to evaluate the potential of yoga practice as a preventive strategy against sarcopenia in Indonesian older adults.

Methods

An observational cross-sectional research was conducted including 41 older adults aged 60-87 years. The research focused on key biomarkers and functional assessments, including serum insulin-like growth factor 1 (IGF-1) levels, telomere length, gait speed, hand grip strength, and SARC-F questionnaire scores.

Results

The results showed that participants aged 71-80 years who practiced yoga for more than a year had significantly higher IGF-1 levels (p=0.04). While improvements in gait speed, hand grip strength, and SARC-F scores were observed, these changes were not statistically significant, and no significant differences were found in telomere length.

Conclusion

Yoga in older adults was associated with higher IGF-1 levels and potential improvements in upper and lower extremity strength, though these findings were not statistically significant and did not influence telomere length. Yoga practice shows potential as an emerging adjuvant option but can not be applied as a single strategy for sarcopenia prevention in older adults.

Deficit Accumulation Index and Biological Markers of Aging in Survivors of Childhood Cancer

Importance

Survivors of childhood cancer experience premature aging compared with community controls. The deficit accumulation index (DAI) uses readily available clinical data to measure physiological age in survivors; however, little data exist on how well deficit accumulation represents underlying biological aging among survivors of cancer.

Objective

To examine the associations between the DAI and epigenetic age acceleration (EAA) and mean leukocyte telomere length (LTL).

Design, Setting, and Participants

This cross-sectional study analyzed data from the St Jude Lifetime Cohort, an assessment of survivors of childhood cancer who were treated at St Jude Children's Research Hospital in Memphis, Tennessee. Data were collected between 2007 and 2016, assayed between 2014 and 2019, and analyzed between 2022 and 2023. Participants were adult survivors who were diagnosed between 1962 and 2012 and who survived 5 years or more from time of diagnosis. The analyses were restricted to survivors with European ancestry, as there were too few survivors with non-European ancestry.

Exposures

The DAI included 44 aging-related items, such as chronic health conditions and functional, psychosocial, and mental well-being. Item responses were summed and divided by the total number of items, resulting in a ratio ranging from 0 to 1. These DAI results were categorized based on reported associations with hospitalization and mortality: low, defined as a DAI less than 0.2; medium, defined as a DAI of 0.2 to less than 0.35; and high, defined as a DAI of 0.35 or higher.

Main Outcomes and Measures

Genome-wide DNA methylation was generated from peripheral blood mononuclear cell-derived DNA. The EAA was calculated as the residuals from regressing the Levine epigenetic age on chronological age. The mean LTL was estimated using whole-genome sequencing data.

Results

This study included 2101 survivors of childhood cancer (1122 males [53.4%]; mean [SD] age, 33.9 [9.1] years; median [IQR] time since diagnosis, 25.1 [18.7-31.9] years) with European ancestry. Compared with survivors in the low DAI group, those in the high DAI group experienced 3.7 more years of EAA (β = 3.66; 95% CI, 2.47-4.85; P < .001), whereas those in the medium DAI group experienced 1.8 more years of EAA (β = 1.77; 95% CI, 0.84-2.69; P < .001), independent of treatment exposures. The EAA and DAI association was consistent across 3 common diagnoses (acute lymphoblastic leukemia, Hodgkin lymphoma, and central nervous system tumors) and across chronological age groups. For example, among acute lymphoblastic leukemia survivors, those in the medium DAI group (β = 2.27; 95% CI, 0.78-3.76; P = .001) experienced greater EAA vs those in the low DAI group. Similarly, among survivors younger than 30 years, the high DAI group experienced 4.9 more years of EAA vs the low DAI group (β = 4.95; 95% CI, 2.14-7.75; P < .001). There were no associations between mean LTL residual and the DAI.

Conclusions and Relevance

This cross-sectional study of survivors of childhood cancer showed that the DAI was associated with EAA, suggesting an underlying biological process to the accumulation of deficits. Both the DAI and EAA were effective at identifying aging phenotypes, and either may be used to measure aging and response to interventions targeting aging pathways.

Frailty biomarkers under the perspective of geroscience: A narrative review

Cellular and molecular aging biomarkers might contribute to identify at-risk individuals for frailty before overt clinical manifestations appear. Although studies on the associations of aging biomarkers and frailty exist, no investigation has gathered this information using a structured framework for identifying aging biomarkers; as a result, the evidence on frailty and aging biomarkers is diffuse and incomplete. Therefore, this narrative review aimed to gather information on the associations of the hallmarks of aging and frailty under the perspective of geroscience. The literature on human studies on this topic is sparse and mainly composed of cross-sectional investigations performed in small study samples. The main putative aging biomarkers associated to frailty were: mitochondrial DNA copy number (genomic instability and mitochondrial dysfunction), telomere length (telomere attrition), global DNA methylation (epigenetic alterations), Hsp70 and Hsp72 (loss of proteostasis), IGF-1 and SIRT1 (deregulated nutrient-sensing), GDF-15 (mitochondrial dysfunction, cellular senescence and altered intercellular communication), CD4 + and CD8 + cell percentages (cellular senescence), circulating osteogenic progenitor (COP) cells (stem cell exhaustion), and IL-6, CRP and TNF-alpha (altered intercellular communication). IGF-1, SIRT1, GDF-15, IL-6, CRP and TNF-alpha presented more evidence among these biomarkers, highlighting the importance of inflammation and nutrient sensing on frailty. Further longitudinal studies investigating biomarkers across the hallmarks of aging would provide valuable information on this topic.

Epigenetic Clock and Leukocyte Telomere Length Are Associated with Vitamin D Status but not with Functional Assessments and Frailty in the Berlin Aging Study II

DNA methylation (DNAm) age acceleration, a parameter derived via the epigenetic clock, has recently been suggested as a biomarker of aging. We hypothesized that accelerated biological aging, measured by both this new and the established biomarker of aging, relative leukocyte telomere length (rLTL), are associated with vitamin D deficiency. Moreover, we tested for an association between rLTL/DNAm age acceleration and different clinical assessments for functional capacity, including the Fried frailty score. Cross-sectional data of 1,649 participants of the Berlin Aging Study II was available (~50% female, age: 22-37 and 60-84 years). A seven cytosine-phosphate-guanine clock was estimated to calculate the DNAm age acceleration. rLTL was measured by quantitative real-time polymerase chain reaction (PCR). 25-hydroxyvitamin D (25(OH)D) serum levels <25 nmol/L was defined as vitamin D deficiency and <50 nmol/L as vitamin D insufficiency. Vitamin D-sufficient individuals had a 1.4 years lower mean DNAm age acceleration (p < .05, analysis of variance [ANOVA]) and a 0.11 longer rLTL (p < .001, ANOVA) than vitamin D-deficient participants. Likewise, vitamin D-sufficient participants had lower DNAm age acceleration (β = 1.060, p = .001) and longer rLTL (β = -0.070; p < .001) than vitamin D nonsufficient subjects in covariate-adjusted analysis. Neither DNAm age acceleration nor rLTL were significantly associated with the Fried frailty score or the functional assessments. Only the clock drawing test was associated with DNAm age acceleration (subgroup of older men: β = 1.898, p = .002). Whether the analyzed biomarkers of aging can be used to predict an individual's functional capacity or will be associated with frailty in the advanced course of aging, will be clarified by future longitudinal analyses.

Expression of Telomeric Repeat-Containing RNA Decreases in Sarcopenia and Increases after Exercise and Nutrition Intervention

Sarcopenia is defined as aging-related loss of muscle mass and function. Telomere length in chromosomes shortens with age and is modulated by telomeric repeat-containing RNA (TERRA). This study aimed to explore the impact of aging and sarcopenia on telomere length and TERRA expression, and changes following strengthening exercise and nutrition intervention (supplement of branched-chain amino acids, calcium and vitamin D3) for 12 weeks in the sarcopenic population. Older adults (≥65 years old) were divided into non-sarcopenic controls (n = 36) and sarcopenic individuals (n = 36) after measurement of grip strength and body composition. The relative telomere length of leukocytes in all research participants was evaluated using the T/S ratio (telomere/single copy gene), and relative TERRA expression of leukocytes was determined by reverse-transcription qPCR (RT-qPCR). Generalized estimating equation (GEE) was used to analyze the influence of sarcopenia and intervention on the outcomes. There was no significant difference in telomere length between control subjects and participants with sarcopenia. TERRA expression was lower in sarcopenic participants compared to that in non-sarcopenic controls (5.18 ± 2.98 vs. 2.51 ± 1.89; p < 0.001). In the sarcopenic group, intervention significantly increased TERRA expression, but not telomere length. The GEE analysis demonstrated that TERRA expression was negatively associated with sarcopenia (β coefficient = −2.705, p < 0.001) but positively associated with intervention (β coefficient = 1.599, p = 0.023). Sarcopenia is associated with a decrease in TERRA expression in leukocytes. Rebound TERRA expression (returning to the level similar to the non-sarcopenic controls) was observed in the sarcopenic group after exercise and nutrition intervention. Future studies are warranted to examine the potential of TERRA as a biomarker for sarcopenia and its subsequent responses to intervention.

Association between telomere length, frailty and death in older adults

Frailty is considered a clinical marker of functional ageing. Telomere length (TL) has been proposed as a biomarker of biological age but its role in human ageing is controversial. The main aim of the study was to evaluate the longitudinal association of TL with incident frailty and mortality in two cohorts of Spanish community-dwelling older adults. TL was determined at baseline in blood samples from older adults included in Toledo Study for Healthy Aging and ENRICA cohorts while frailty was determined by frailty phenotype (FP) at baseline and at follow-up (3.5 years). Deaths occurring during follow-up were also recorded. Associations of TL with frailty and mortality were analysed by logistic regression with progressive adjustment. Data were separately analysed in the two cohorts and in all subjects by performing a meta-analysis. TL was not different between frail and non-frail subjects. Longer telomeres were not associated with lower risk of prevalent frailty. Similarly, TL at baseline failed to predict incident frailty (OR: 1.04 [0.88-1.23]) or even the development of a new FP criterion (OR: 0.97 [0.90-1.05]) at follow-up. Lack of association was also observed when analysing the development of specific FP criteria. Finally, while frailty at baseline was significantly associated with higher risk of death at follow-up (OR: 4.08 [1.97-8.43], p < 0.001), TL did not significantly change the mortality risk (OR: 1.05 [0.94-1.16]). Results show that TL does not predict incident frailty or mortality in older adults. This suggests that TL is not a reliable biomarker of functional age.

The joint effects of frailty and telomere length for predicting mortality in older adults: the National Health and Nutrition Examination Survey 1999-2002

BACKGROUND

Frailty and short telomere length, which address different aspects of biological aging, are separately associated with mortality in older adults.

AIMS

To evaluate whether the combination of these two biomarkers would be a better predictor of mortality than either alone.

METHODS

This present study included participants 60 years of age or older from the National Health and Nutrition Examination Survey in the 1999-2002 phase. The frailty phenotype was identified based on the Fried definition. Telomere length relative to standard reference DNA (T/S ratio) was assessed using quantitative polymerase chain reaction (PCR). Cox proportional hazards regression models were used to estimate the individual and combined effects of frailty phenotype and telomere length on all-cause and cardiovascular mortality.

RESULTS

Compared with participants with neither impairment, the mortality risks increased slightly among participants with short telomere length only (hazard ratio [HR] 1.19, 95% confidence interval [CI]: 1.00-1.42) or pre-frailty only (HR 2.16, 95% CI 1.80-2.60) and gradually elevated approximately 3 folds with both short telomere length and pre-frailty (HR 2.23, 95% CI 1.81-2.74) or frailty (HR 3.57, 95% CI 2.56-4.98). Moreover, participants with both short telomere length and frailty had the highest increased all-cause mortality (HR 5.16, 95% CI 3.38-7.85) and cardiovascular mortality (HR 4.67, 95% CI 2.02-10.82).

DISCUSSION AND CONCLUSIONS

The combined predictor had more capability of predicting mortality, which suggested that integrating both molecular biomarkers and physiological functional parameters would be a more informative measure of biological aging.

Telomere length and frailty in older adults-A systematic review and meta-analysis

Telomere shortening has been proposed as a potentially useful biomarker of human ageing and age-related morbidity and mortality. We performed a systematic review and meta-analysis to summarize results from individual studies on the telomere length according to the frailty status and frailty index in older adults. We searched the PubMed, SCOPUS and Web of Science databases to identify studies that evaluated the telomere length in frail and non-frail older adults and the relationship between telomere length and frailty index score. We used the base pairs (bp) as a measure of the telomere length. Summary estimates were calculated using random-effects models. Nine studies were included in the present systematic review and a total of 10,079 older adults were analyzed. We found that the frail older adults (n = 355) had shorter telomeres than the non-frail (n = 1894) (Standardized Mean Difference [SMD] -0.41; 95% CI -0.73 to -0.09; P = 0.01; I² = 82%). Significant differences in telomere length between frail and non-frail older adults were identified in Hispanic (SMD -1.31; 95% CI -1.71 to -0.92; P < 0.0001; I² = 0%) but not in Non-Hispanic countries (SMD -0.13; 95% CI -0.26 to 0.00; P = 0.06; I² = 0%). Similar results were found in the adjusted meta-analysis (SMD -0.56; 95% -1.12 to 0.00; P = 0.05; I² = 85%). A significant but weak relationship was found between telomere length and frailty index analyzing 8244 individuals (SMD -0.06; 95% IC -0.10 to 0.01; P = 0.01; I² = 0%). The current available evidence suggests that telomere length may be not a meaningful biomarker for frailty. Because the potential influence of ethnicity in shortening of telomeres and decline in physiologic reserves associated with aging, additional multiethnic studies are needed.

Frailty biomarkers in humans and rodents: Current approaches and future advances

Even though they would have great benefit across research and clinical fields, currently there are no accepted biomarkers of frailty. Cross-sectional studies in humans have identified promising candidates including inflammatory markers such as IL-6, immune markers such as WBC count, clinical markers such as albumin, endocrine markers such as vitamin D, oxidative stress markers such as isoprostanes, proteins such as BDNF and epigenetic markers such as DNA methylation, but there are limitations to the current state of the research. Future approaches to the identification of frailty biomarkers should include longitudinal studies, studies using animal models of frailty, studies incorporating novel biomarkers combined into composite panels, and studies investigating sex differences and potential overlap between markers of biological age and frailty.

Blood Markers in Healthy-Aged Nonagenarians: A Combination of High Telomere Length and Low Amyloidβ Are Strongly Associated With Healthy Aging in the Oldest Old

Many factors may converge in healthy aging in the oldest old, but their association and predictive power on healthy or functionally impaired aging has yet to be demonstrated. By detecting healthy aging and in turn, poor aging, we could take action to prevent chronic diseases associated with age. We conducted a pilot study comparing results of a set of markers (peripheral blood mononuclear cell or PBMC telomere length, circulating Aβ peptides, anti-Aβ antibodies, and ApoE status) previously associated with poor aging or cognitive deterioration, and their combinations, in a cohort of “neurologically healthy” (both motor and cognitive) nonagenarians (n = 20) and functionally impaired, institutionalized nonagenarians (n = 38) recruited between 2014 and 2015. We recruited 58 nonagenarians (41 women, 70.7%; mean age: 92.37 years in the neurologically healthy group vs. 94.13 years in the functionally impaired group). Healthy nonagenarians had significantly higher mean PBMC telomere lengths (mean = 7, p = 0.001), this being inversely correlated with functional impairment, and lower circulating Aβ40 (total in plasma fraction or TP and free in plasma fraction or FP), Aβ42 (TP and FP) and Aβ17 (FP) levels (FP40 131.35, p = 0.004; TP40 299.10, p = 0.007; FP42 6.29, p = 0.009; TP42 22.53, p = 0.019; FP17 1.32 p = 0.001; TP17 4.47, p = 0.3), after adjusting by age. Although healthy nonagenarians had higher anti-Aβ40 antibody levels (net adsorbed signal or NAS ± SD: 0.211 ± 0.107), the number of participants that pass the threshold (NAS > 3) to be considered as positive did not show such a strong association. There was no association with ApoE status. Additionally, we propose a “Composite Neurologically Healthy Aging Score” combining TP40 and mean PBMC telomere length, the strongest correlation of measured biomarkers with neurologically healthy status in nonagenarians (AUC = 0.904).

Telomere shortening and frailty in Mexican older adults

AIM

Telomere shortening has been associated with several age-related diseases, in addition to being considered a hallmark of aging. Frailty is a clinical syndrome characterized by an accentuated physiological and functional decline that might be a predictor of an adverse condition in older age. The present study evaluated the relationship between frailty and telomere shortening in older adults from Mexico City, Mexico.

METHODS

This was a cross-sectional study. Data were collected from 323 frail older adults, including physical and environmental factors, such as body mass index, comorbidities, physical activity and tobacco consumption. Telomere length was measured by real-time polymerase chain reaction. The frailty syndrome was diagnosed using the Fried criteria.

RESULTS

An association between frailty and telomere shortening was found in both sexes. Telomere length decreased from 6.05 kb (5.54-6.48 kb) to 4.20 kb (3.80-4.54 kb; P < 0.001). It was also observed that tobacco consumption could be a significant modifying factor in the association between these two variables. Previous reports are contradictory, suggesting that there is no relationship between telomere length and frailty; however, it is possible that there are genetic and/or environmental variables to be elucidated, that might influence this association, particularly in the studied population.

CONCLUSIONS

Telomere length is inversely related to frailty in Mexican frail older adults, and tobacco consumption is the main environmental modifying factor. Geriatr Gerontol Int 2018; 18: 1286-1292.

A review of telomere length in sarcopenia and frailty

Sarcopenia and frailty are associated with several important health-related adverse events, including disability, loss of independence, institutionalization and mortality. Sarcopenia can be considered a biological substrate of frailty, and the prevalence of both these conditions progressively increases with age. Telomeres are nucleoprotein structures located at the end of linear chromosomes and implicated in cellular ageing, shorten with age, and are associated with various age-related diseases. In addition, telomere length (TL) is widely considered a molecular/cellular hallmark of the ageing process. This narrative review summarizes the knowledge about telomeres and analyzes for the first time a possible association of TL with sarcopenia and frailty. The overview provided by the present review suggests that leukocyte TL as single measurement, calculated by quantitative real-time polymerase chain reaction (qRT-PCR), cannot be considered a meaningful biological marker for complex, multidimensional age-related conditions, such as sarcopenia and frailty. Panels of biomarkers, including TL, may provide more accurate assessment and prediction of outcomes in these geriatric syndromes in elderly people.

The association between telomere length and frailty: A systematic review and meta-analysis

BACKGROUND

Several studies have examined the association between telomere length and frailty, but results from these studies are contradictory. Therefore, we conducted a systematic review and meta-analysis to examine the association between telomere length and frailty.

METHODS

We searched the literature in Ovid (MEDLINE), Embase, PubMed, Web of Knowledge and Cochrane databases in July 2017 for studies evaluating the association of telomere length and the risk of frailty.

RESULTS

A total of 5 studies (3268 participants) were eligible in our study. The prevalence of frailty ranged from 5.4% to 51.1%. The pooled mean difference of telomere length for the non-frail versus frail was 0.06 (95% CI: -0.01, 0.13), suggesting that no significant association was found between telomere length and frailty. In addition, the subgroup analysis indicated that telomere length was not significantly associated with the risk of frailty in all gender groups. Similar results were also found when frailty was defined by the Fried criteria (mean difference = 0.07, 95% CI: -0.03, 0.16) and frailty index (mean difference = -0.02, 95% CI: -0.05, 0.01), but not by the frailty scale (mean difference = 0.18, 95% CI: 0.04, 0.32).

CONCLUSION

Telomere length is not associated with the risk of frailty. Well-designed prospective studies are needed to evaluate further whether telomere length is a meaningful biological marker for frailty.

The association of sarcopenia, telomere length, and mortality: data from the NHANES 1999-2002

BACKGROUND/OBJECTIVES

Sarcopenia is defined as the loss of muscle mass or function with aging and is associated with adverse outcomes. Telomere shortening is associated with mortality, yet its relationship with sarcopenia is unknown.

SUBJECTS/METHODS

Adults ≥60 years from the 1999-2002 NHANES with body composition measures were identified. Sarcopenia was defined using the two Foundation for the National Institute of Health definitions: appendicular lean mass (ALM) (men <19.75; women <15.02 kg); or ALM divided by body mass index (BMI) (ALM:BMI, men <0.789; women <0.512). Telomere length was assessed using quantitative PCR. Regression models predicted telomere length with sarcopenia (referent = no sarcopenia).

RESULTS

We identified 2672 subjects. Mean age was 70.9 years (55.5% female). Prevalence of ALM and ALM:BMI sarcopenia was 29.2 and 22.1%. Deaths were higher in persons with sarcopenia as compared to those without sarcopenia (ALM: 46.4 vs. 33.4%, p < 0.001; ALM:BMI: 46.7 vs. 33.2%, p < 0.001). No adjusted differences were observed in telomere length in those with/without sarcopenia (ALM: 0.90 vs. 0.92, p = 0.74, ALM:BMI 0.89 vs. 0.92, p = 0.24). In men with ALM:BMI-defined sarcopenia, adjusted telomere length was significantly lower compared to men without sarcopenia (0.85 vs. 0.91, p = 0.013). With sarcopenia, we did not observe a significant association between telomere length and mortality (ALM: HR 1.11 [0.64,1.82], p = 0.68; ALM:BMI: HR 0.97 [0.53,1.77], p = 0.91), but noted significance in those without sarcopenia with mortality (ALM: HR 0.59 [0.40,0.86], p = 0.007; ALM:BMI: HR 0.62 [0.42,0.91]; p = 0.01).

CONCLUSIONS

We observed a potentially inverse relationship between telomere length and mortality in those without sarcopenia but did not observe a significant relationship between telomere length and mortality in the presence of sarcopenia.

Oxidative stress, genomic features and DNA repair in frail elderly: A systematic review

Frailty is an emerging geriatric syndrome characterized by higher vulnerability to stressors, with an increased risk of adverse health outcomes such as mortality, morbidity, disability, hospitalization, and institutionalization. Although it is generally recognized to have a biological basis, no particular biological trait has been consistently associated to frailty status so far. In this work, epidemiological studies evaluating association of frailty status with alterations at cellular level - namely oxidative stress, genomic instability and DNA damage and repair biomarkers -were revised and compared. A total of 25 studies fulfilled inclusion/exclusion criteria and, consequently, were included in the review. Variations of oxidative stress biomarkers were often associated to frailty status in older people. On the contrary, genomic instability seems not to be linked to frailty. The only study which addressed the possible relationship between DNA repair modulations and frailty status also failed in finding association. Despite the large number of cellular alterations known to be associated with frailty, studies on this issue are still very scarce and limited to some of the possible cellular targets. The established link between DNA repair, genomic instability, and age and age-related disorders, encourage deeper investigations on this line.

Tobacco smoking and smoking-related DNA methylation are associated with the development of frailty among older adults

Tobacco smoking is a preventable environmental factor that contributes to a wide spectrum of age-related health outcomes; however, its association with the development of frailty is not yet well established. We examined the associations of self-reported smoking indicators, serum cotinine levels and smoking-related DNA methylation biomarkers with a quantitative frailty index (FI) in 2 independent subsets of older adults (age 50-75) recruited in Saarland, Germany in 2000 - 2002 (discovery set: n = 978, validation set: n = 531). We obtained DNA methylation profiles in whole blood samples by Illumina HumanMethylation450 BeadChip and calculated the FI according to the method of Mitnitski and Rockwood. Mixed linear regression models were implemented to assess the associations between smoking indicators and the FI. After controlling for potential covariates, current smoking, cumulative smoking exposure (pack-years), and time after smoking cessation (years) were significantly associated with the FI (P-value < 0.05). In the discovery panel, 17 out of 151 previously identified smoking-related CpG sites were associated with the FI after correction for multiple testing (FDR < 0.05). Nine of them survived in the validation phase and were designated as frailty-associated loci. A smoking index (SI) based on the 9 loci manifested a monotonic association with the FI. In conclusion, this study suggested that epigenetic alterations could play a role in smoking-associated development of frailty. The identified CpG sites have the potential to be prognostic biomarkers of frailty and frailty-related health outcomes. Our findings and the underlying mechanisms should be followed up in further, preferably longitudinal studies.

Screening for Frailty in Canada's Health Care System: A Time for Action

As Canada's population ages, frailty - with its increased risk of functional decline, deterioration in health status, and death - will become increasingly common. The physiology of frailty reflects its multisystem, multi-organ origins. About a quarter of Canadians over age 65 are frail, increasing to over half in those older than 85. Our health care system is organized around single-organ systems, impairing our ability to effectively treat people having multiple disorders and functional limitations. To address frailty, we must recognize when it occurs, increase awareness of its significance, develop holistic models of care, and generate better evidence for its treatment. Recognizing how frailty impacts lifespan will allow for integration of care goals into treatment options. Different settings in the Canadian health care system will require different strategies and tools to assess frailty. Given the magnitude of challenges frailty poses for the health care system as currently organized, policy changes will be essential.

Biology of frailty: Modulation of ageing genes and its importance to prevent age-associated loss of function

Frailty is associated with loss of functional reserve as well as with the prediction of adverse events in the old population. The traditional criteria of frailty are based on five physical determinations described in the Cardiovascular Health Study. We propose that biological and genetic markers of frailty should be used to increase the predictive capacity of the established clinical indeces. In recent times, research for biological markers of frailty has gained impetus. Finding a biological markers with diagnostic and prognostic capacity would be a major milestone to identify frailty risk, and also pre-frailty status. In the first section of the manuscript, we review the available biomarkers that help to monitor and prevent the evolution and the efficacy of interventions to delay the onset of frailty and to prevent its progression to incapacity. We also discuss the contribution of genetics to frailty. There are scientific bases that support that genetics influences frailty, although environmental factors probably will have the highest contribution. We review the known SNPs of the genes associated with frailty and classify them, taking into account the pathway in which they are involved. We also highlight the importance of longevity genes and their possible relation with frailty, citing centenarians who reach a very old age as an example of successful ageing. Finally, the reversibility of frailty is discussed. It can potentially be treated with nutritional or pharmacological interventions. However, physical exercise seems to be the most effective strategy to treat and prevent frailty. The last section of the manuscript is devoted to explaining the recommendations on the appropriate design of an exercise protocol to maximize its beneficial effects in a population of frail individuals.

Frailty is associated with the epigenetic clock but not with telomere length in a German cohort

Background

The epigenetic clock, in particular epigenetic pre-aging quantified by the so-called DNA methylation age acceleration, has recently been suggested to closely correlate with a variety of disease phenotypes. There remains a dearth of data, however, on its association with telomere length and frailty, which can be considered major correlates of age on the genomic and clinical level, respectively.

Results

In this cross-sectional observational study on altogether 1820 subjects from two subsets (n = 969 and n = 851; mean ± standard deviation age 62.1 ± 6.5 and 63.0 ± 6.7 years, respectively) of the ESTHER cohort study of the elderly general population in Germany, DNA methylation age was calculated based on a 353 loci predictor previously developed in a large meta-study, and the difference-based epigenetic age acceleration was calculated as predicted methylation age minus chronological age. No correlation of epigenetic age acceleration with telomere length was found in our study (p = 0.63). However, there was an association of DNA methylation age acceleration with a comprehensive frailty measure, such that the accumulated deficits significantly increased with increasing age acceleration. Quantitatively, about half an additional deficit was added per 6 years of methylation age acceleration (p = 0.0004). This association was independent from age, sex, and estimated leukocyte distribution, as well as from a variety of other confounding variables considered.

Conclusions

The results of the present study suggest that epigenetic age acceleration is correlated with clinically relevant aging-related phenotypes through pathways unrelated to cellular senescence as assessed by telomere length. Innovative approaches like Mendelian randomization will be needed to elucidate whether epigenetic age acceleration indeed plays a causal role for the development of clinical phenotypes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-016-0186-5) contains supplementary material, which is available to authorized users.

[Frailty in Germany: status and perspectives : Results from a workshop of the German Society for Epidemiology]

BACKGROUND

A standardized, valid and comparable operationalization and assessment of frailty in population-based studies is essential in order to describe the prevalence and determinants of frailty in the population.

AIM

After an introduction to the subject the main goal of a workshop at the 9th annual meeting of the German Society for Epidemiology (DGEpi) was to present approaches and results from four different studies in Germany.

MATERIAL AND METHODS

The following four population-based studies were used to describe frailty in Germany: the German health interview and examination survey for adults (DEGS1), the epidemiological study on the chances of prevention, early recognition and optimized treatment of chronic diseases in the older population (ESTHER), the cooperative health research in the region Augsburg (KORA Age) study and the longitudinal urban cohort ageing study (LUCAS) in Hamburg.

RESULTS

The four studies consistently showed that frailty is widespread in older and oldest-old persons in Germany. It is obvious that frailty represents a relevant concept in Germany even if there is currently no uniform basis for operationalization.

CONCLUSION

Concepts and instruments for the collation of frailty should be included in future population-based studies in order to make a better assessment of older people's health situation and to describe the unused potential for prevention in an aging society.

Depression and frailty in later life: a systematic review

Frailty and depression are important issues affecting older adults. Depressive syndrome may be difficult to clinically disambiguate from frailty in advanced old age. Current reviews on the topic include studies with wide methodological variation. This review examined the published literature on cross-sectional and longitudinal associations between frailty and depressive symptomatology with either syndrome as the outcome, moderators of this relationship, construct overlap, and related medical and behavioral interventions. Prevalence of both was reported. A systematic review of studies published from 2000 to 2015 was conducted in PubMed, the Cochrane Database of Systematic Reviews, and PsychInfo. Key search terms were "frailty", "frail", "frail elderly", "depressive", "depressive disorder", and "depression". Participants of included studies were ≥ 55 years old and community dwelling. Included studies used an explicit biological definition of frailty based on Fried et al's criteria and a screening measure to identify depressive symptomatology. Fourteen studies met the inclusion/exclusion criteria. The prevalence of depressive symptomatology, frailty, or their co-occurrence was greater than 10% in older adults ≥ 55 years old, and these rates varied widely, but less in large epidemiological studies of incident frailty. The prospective relationship between depressive symptomatology and increased risk of incident frailty was robust, while the opposite relationship was less conclusive. The presence of comorbidities that interact with depressive symptomatology increased incident frailty risk. Measurement variability of depressive symptomatology and inclusion of older adults who are severely depressed, have cognitive impairment or dementia, or stroke may confound the frailty syndrome with single disease outcomes, accounting for a substantial proportion of shared variance in the syndromes. Further study is needed to identify medical and behavioral interventions for frailty and depressive symptomatology that prevent adverse sequelae such as falls, disability, and premature mortality.

Telomere length is not associated with frailty in older Chinese elderly: Cross-sectional and longitudinal analysis

Telomere shortening has been associated with biological age and several chronic degenerative diseases. However, less is known about telomere length and frailty, which is an indicator of biological age. This study examines the association between telomere length and frailty in a prospective study over five years of 2006 men and women aged 65 years and older living in the community. The frailty status was determined by the Fried's criteria. Telomere length in leukocytes was measured using the quantitative polymerase chain reaction. Logistic regression was used to examine the association between telomere length and incidence of frailty. Among 2006 subjects (mean age 72.4±5.1 years, 51.3% women), the mean telomere length at baseline was 9.1±2.0kb and the frailty phenotype was detected in 127 subjects (6.3%). Male gender was related to shorter telomere length, with increased years of age related to a shortened telomere length (P<0.05). In both men and women, no statistically significant difference of telomere length and the frailty phenotype was observed at baseline. After 4 years of follow-up, 116 cases of frailty were identified. There was no association between telomere length and incident frailty. In conclusion, telomere length was not associated with frailty in this study population.

Markers of T-cell senescence and physical frailty: insights from Singapore Longitudinal Ageing Studies

BACKGROUND

Elderly individuals have an eroded immune system but whether immune senescence is implicated with the development of frailty is unknown. The underlying immune mechanisms and the link between markers of senescence and physical frailty is not well established.

METHODS

We explored the association of specific T-cell subset markers of immune differentiation and senescence on CD4⁺ and CD8⁺ cells (CD28^-, CD27^- and CD57⁺) and the immune risk profile (inverted CD4/CD8 ratio <1) with physical frailty among 421 participants who were frail (N=32), prefrail (N=187) and robust (N=202) in the Singapore Longitudinal Ageing Study cohort.

RESULTS

In ordinal logistic regression models relating tertile category rank scores of immune biomarker with frailty status (robust, prefrail and frail), CD8⁺CD28^-CD27⁺ (odds ratio (OR)=1.35, P=0.013), CD4⁺CD28^-CD27⁺ (OR=1.29, P=0.025), CD8⁺CD28^- (OR=1.31, P=0.022), and CD4/CD8 ratio (OR=1.27, P=0.026) were positively associated with frailty, controlling for age, sex and multimorbidity. CD4/CD8 ratio less than one was not associated with frailty (OR=0.84, P=0.64). In stepwise multinomial logistic regression controlling for age, sex and comorbidity, only CD8⁺CD28^-CD27⁺ was the independent predictor of prefrailty: highest tertile of the immune marker significantly predicted prefrailty (versus low tertile, OR=1.72, P=0.037) and frailty (OR=2.56, P=0.06).

CONCLUSION

The study supports the hypothetical role of immune senescence in physical frailty, particularly in regard to the observed loss of CD28 expression from both CD8⁺ cells and CD4⁺ cells, but not for CD27 or CD4/CD8 ratio as a marker of senescence. The potential of CD8⁺CD28^-CD27⁺ as a biological marker of frailty should be further investigated in prospective studies.

Micronucleus frequency in peripheral blood lymphocytes and frailty status in elderly. A lack of association with clinical features

Frailty is a condition of vulnerability that carries an increased risk of poor outcome in elder adults. Frail individuals show fatigue, weight loss, muscle weakness, and a reduced physical function, and are known to frequently experience disability, social isolation, and institutionalization. Identifying frail people is a critical step for geriatricians to provide timely geriatric care and, eventually, to improve the quality of life in elderly. The aim of the present study is to investigate the association between frailty status and micronucleus (MN) frequency, a known marker of genomic instability, in a sample of elder adults. Several clinical features were evaluated and their possible association with MN frequency was tested. Criteria proposed by Fried were used to identify frail subjects. Overall, 180 elder adults entered the study, 93 of them (51.7%) frail. No association between MN frequency and frailty status was found under the specific conditions tested in this study (mean ratio=1.06; 95% CI 0.96-1.18). The inclusion of MN frequency in the Fried's frailty scale minimally improved the classification of study subjects according to the multidimensional prognostic index (MPI). The presence of genomic instability in the ageing process and in most chronic diseases, demands further investigation on this issue.

Age-related frailty and its association with biological markers of ageing

BACKGROUND

The relationship between age-related frailty and the underlying processes that drive changes in health is currently unclear. Considered individually, most blood biomarkers show only weak relationships with frailty and ageing. Here, we examined whether a biomarker-based frailty index (FI-B) allowed examination of their collective effect in predicting mortality compared with individual biomarkers, a clinical deficits frailty index (FI-CD), and the Fried frailty phenotype.

METHODS

We analyzed baseline data and up to 7-year mortality in the Newcastle 85+ Study (n = 845; mean age 85.5). The FI-B combined 40 biomarkers of cellular ageing, inflammation, haematology, and immunosenescence. The Kaplan-Meier estimator was used to stratify participants into FI-B risk strata. Stability of the risk estimates for the FI-B was assessed using iterative, random subsampling of the 40 FI-B items. Predictive validity was tested using Cox proportional hazards analysis and discriminative ability by the area under receiver operating characteristic (ROC) curves.

RESULTS

The mean FI-B was 0.35 (SD, 0.08), higher than the mean FI-CD (0.22; SD, 0.12); no participant had an FI-B score <0.12. Higher values of each FI were associated with higher mortality risk. In a sex-adjusted model, each one percent increase in the FI-B increased the hazard ratio by 5.4 % (HR, 1.05; CI, 1.04-1.06). The FI-B was more powerful for mortality prediction than any individual biomarker and was robust to biomarker substitution. The ROC analysis showed moderate discriminative ability for 7-year mortality (AUC for FI-CD = 0.71 and AUC for FI-B = 0.66). No individual biomarker's AUC exceeded 0.61. The AUC for combined FI-CD/FI-B was 0.75.

CONCLUSIONS

Many biological processes are implicated in ageing. The systemic effects of these processes can be elucidated using the frailty index approach, which showed here that subclinical deficits increased the risk of death. In the future, blood biomarkers may indicate the nature of the underlying causal deficits leading to age-related frailty, thereby helping to expose targets for early preventative interventions.

How old do you feel? The role of age discrimination and biological aging in subjective age

Subjective age, or how young or old individuals experience themselves to be relative to their chronological age, is a crucial construct in gerontology. Subjective age is a significant predictor of important health outcomes, but little is known about the criteria by which individuals' subjectively evaluate their age. To identify psychosocial and biomedical factors linked to the subjective evaluation of age, this study examined whether perceived age discrimination and markers of biological aging are associated with subjective age. Participants were 4776 adults (M_age = 68) from the 2008 and 2010 waves of the Health and Retirement Study (HRS) who completed measures of subjective age, age discrimination, demographic variables, self-rated health and depression, and had physical health measures, including peak expiratory flow, grip strength, waist circumference, systolic and diastolic blood pressure. Telomere length was available for a subset of participants in the 2008 wave (n = 2214). Regression analysis indicated that perceived age discrimination, lower peak expiratory flow, lower grip strength, and higher waist circumference were associated with an older subjective age, controlling for sociodemographic factors, self-rated health, and depression. In contrast, blood pressure and telomere length were not related to subjective age. These findings are consistent with the hypothesis that how old a person feels depends in part on psychosocial and biomedical factors, including the experiences of ageism and perceptible indices of fitness and biological age.