Telomere shortening and frailty in Mexican older adults

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.

Physical Performance and Telomere Length in Older Adults

BACKGROUND

The aging population prompts studying risk factors and markers to predict healthy aging. Telomere length is a promising candidate for assessing various age-related traits.

AIM OF THE STUDY

To investigate the association between physical performance and telomere length.

METHODS

We enrolled 323 older Mexican adults from the "Cohort of Obesity, Sarcopenia, and Frailty of Older Mexican Adults" affiliated with the Instituto Mexicano del Seguro Social and assessed their physical performance using the Short Physical Performance Battery, dividing participants into low (≤7) and high (>7) groups. Absolute telomere length was determined by qPCR, and individuals were classified into short (≤4.22 kb) and long (>4.22 kb) groups. We calculated the mean and adjusted mean, considering sex and age, among others, with 95% CI. We estimated the effect size between physical performance and telomere length using Cohen's d for unequal group sizes and calculated the odds ratio for physical performance based on telomere length.

RESULTS

Participants with low physical performance had significantly shorter telomeres (mean 4.14.44.7 kb, adjusted mean 3.54.04.5 kb, p <0.001), while those with high physical performance exhibited longer telomeres (mean 5.55.75.9 kb, adjusted mean 4.75.35.8 kb, p <0.001), with a medium-to-high telomere length effect size (d = 0.762). The odds of low physical activity increased 2.13.66.1-fold per kb of telomere attrition (adjOR 1.73.36.3, p <0.001).

CONCLUSION

Decreased physical function is associated with shorter telomere length. Absolute telomere length presents a promising biomarker for distinguishing between healthy and unhealthy aging, warranting further investigation.

Frailty mediating the causality between leucocyte telomere length and mortality: a cohort study of 440,551 UK Biobank participants

Introduction

Previous studies reported leucocyte telomere length (LTL) and frailty were associated with mortality, but it remains unclear whether frailty serves as a mediator in the relationship between leucocyte telomere length and mortality risk. This study aimed to evaluate how measuring LTL and frailty can support early monitoring and prevention of risk of mortality from the prospective of predictive, preventive, and personalized medicine (PPPM/3PM).

Methods

We included 440,551 participants from the UK Biobank between the baseline visit (2006-2010) and November 30, 2022. The time-dependent Cox proportional hazards model was conducted to assess the association between LTL and frailty index with the risk of mortality. Furthermore, we conducted causal mediation analyses to examine the extent to which frailty mediated the association between LTL and mortality.

Results

During a median follow-up of 13.74 years, each SD increase in LTL significantly decreased the risk of all-cause [hazard ratio (HR): 0.94, 95% confidence interval (CI): 0.93-0.95] and CVD-specific mortality (HR: 0.92, 95% CI: 0.90-0.95). The SD increase in FI elevated the risk of all-cause (HR: 1.35, 95% CI: 1.34-1.36), CVD-specific (HR: 1.47, 95% CI: 1.44-1.50), and cancer-specific mortality (HR: 1.22, 95% CI: 1.20-1.24). Frailty mediated approximately 10% of the association between LTL and all-cause and CVD-specific mortality.

Conclusions

Our results indicate that frailty mediates the effect of LTL on all-cause and CVD-specific mortality. There findings might be valuable to predict, prevent, and reduce mortality through primary prevention and healthcare in context of PPPM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00355-7.

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.

Shortening of leucocyte telomere length is independently correlated with high body mass index and subcutaneous obesity (predominantly truncal), in Asian Indian women with abnormal fasting glycemia

INTRODUCTION

Leucocyte telomere length (LTL) is linked to accelerate aging and premature mortality. In this research, we aimed to explore the relations between biochemical and anthropometry markers and LTL in Asian Indian women with abnormal fasting glycemia (impaired fasting glucose).

RESEARCH DESIGN AND METHODS

In this study, 797 pre-diabetic women (obese, 492; non-obese, 305) were recruited. Demographic and clinical profiles, anthropometry, and fasting blood glucose were evaluated. LTL was quantified by a quantitative PCR. LTL was expressed as the relative telomere length or telomere repeat:single copy gene (T:S) ratio. The subjects were separated into quartiles according to the LTL.

RESULTS

The average LTL was significantly decreased with increasing age. The average LTL was significantly shorter in obese women with abnormal fasting glycemia (p<0.05). R-squared (R²) statistic for multivariable linear model after adjusted for age, family income, education and hypertension showed that LTL was inversely correlated with body mass index (BMI), waist and hip circumference, waist-hip and waist-to-height ratio, truncal skinfolds (subscapular, and subscapular/triceps ratio, central and total skinfolds), fat mass (kg) and % body fat. The relationship between obesity measures and LTL (using the LTL quartile 1 as reference) identified central skinfolds (R²=0.92, p<0.0001), Σ4SF (R²=0.90, p<0.0001), BMI (R²=0.93, p<0.0001) and % body fat (R²=0.91, p<0.0001) as independent predictors of LTL.

CONCLUSIONS

Besides age, obesity and subcutaneous adiposity (predominantly truncal) are major contributors to telomere shortening in Asian Indian women with abnormal fasting glycemia (impaired fasting glucose).

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 associated factors in older adults with hypertension

Telomeres and telomerase play important roles in the occurrence and development of hypertension. This review was performed to clarify the factors that influence telomere length and telomerase activity in older patients and elucidate the association of these factors with hypertension. A PubMed search and critical review of studies assessing the risk factors underlying the association of hypertension with telomere length and telomerase activity was performed. Telomere length and telomerase activity were found to be associated with hypertension. The factors that influence telomere length and telomerase activity in older patients with hypertension include genetics, demographics, social and environmental factors, chronic disease, psychological factors, and antihypertensive drug treatment. A better understanding of the molecular mechanisms underlying the association of hypertension with telomere length and telomerase activity may help to reduce the incidence of hypertension.

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.