Telomere length is associated with decline in grip strength in older persons aged 65 years and over

The effect of low birth weight as an intrauterine exposure on the early onset of sarcopenia through possible molecular pathways

Sarcopenia, a musculoskeletal disease characterized by the progressive loss of skeletal muscle mass, strength, and physical performance, presents significant challenges to global public health due to its adverse effects on mobility, morbidity, mortality, and healthcare costs. This comprehensive review explores the intricate connections between sarcopenia and low birth weight (LBW), emphasizing the developmental origins of health and disease (DOHaD) hypothesis, inflammatory processes (inflammaging), mitochondrial dysfunction, circadian rhythm disruptions, epigenetic mechanisms, and genetic variations revealed through genome-wide studies (GWAS). A systematic search strategy was developed using PubMed to identify relevant English-language publications on sarcopenia, LBW, DOHaD, inflammaging, mitochondrial dysfunction, circadian disruption, epigenetic mechanisms, and GWAS. The publications consist of 46.2% reviews, 21.2% cohort studies, 4.8% systematic reviews, 1.9% cross-sectional studies, 13.4% animal studies, 4.8% genome-wide studies, 5.8% epigenome-wide studies, and 1.9% book chapters. The review identified key factors contributing to sarcopenia development, including the DOHaD hypothesis, LBW impact on muscle mass, inflammaging, mitochondrial dysfunction, the influence of clock genes, the role of epigenetic mechanisms, and genetic variations revealed through GWAS. The DOHaD theory suggests that LBW induces epigenetic alterations during foetal development, impacting long-term health outcomes, including the early onset of sarcopenia. LBW correlates with reduced muscle mass, grip strength, and lean body mass in adulthood, increasing the risk of sarcopenia. Chronic inflammation (inflammaging) and mitochondrial dysfunction contribute to sarcopenia, with LBW linked to increased oxidative stress and dysfunction. Disrupted circadian rhythms, regulated by genes such as BMAL1 and CLOCK, are associated with both LBW and sarcopenia, impacting lipid metabolism, muscle mass, and the ageing process. Early-life exposures, including LBW, induce epigenetic modifications like DNA methylation (DNAm) and histone changes, playing a pivotal role in sarcopenia development. Genome-wide studies have identified candidate genes and variants associated with lean body mass, muscle weakness, and sarcopenia, providing insights into genetic factors contributing to the disorder. LBW emerges as a potential early predictor of sarcopenia development, reflecting the impact of intrauterine exposures on long-term health outcomes. Understanding the complex interplay between LBW with inflammaging, mitochondrial dysfunction, circadian disruption, and epigenetic factors is essential for elucidating the pathogenesis of sarcopenia and developing targeted interventions. Future research on GWAS and the underlying mechanisms of LBW-associated sarcopenia is warranted to inform preventive strategies and improve public health outcomes.

Telomere Length is Associated with the Prevalence, Persistence, and Incidence of Sarcopenia

BACKGROUND

Telomere length (TL) shortening has been identified as a marker of aging and associated with adverse health outcomes, but evidence of its association with sarcopenia is inconclusive.

AIMS

Estimate the cross-sectional and prospective associations between TL and sarcopenia.

METHODS

We used data from Waves 3 and 4 (2017, 2021) of the Study on Global Aging and Adult Health in Mexico (SAGE-Mexico). The cross-sectional sample consisted of 1,738 adults aged 50 and older, and the longitudinal sample consisted of 1,437. Relative TL was determined by real-time quantitative polymerase chain reaction (qPCR) on DNA extracted from saliva samples and quantified as the telomere/single-copy gene (T/S) ratio. Sarcopenia was defined according to the European Working Group on Sarcopenia in Older People (EWGSOP2).

RESULTS

The mean salivary TL was 1.50 T/S units (95% CI: 1.49-1.52). The baseline prevalence of sarcopenia was 13.3% (95% CI: 9.8-16.8%). The incidence and persistence of sarcopenia were 6.8% (95% CI: 5.0-9.5%) and 7.0% (95% CI: 5.1-9.6%), respectively. The results showed that a one standard deviation decrease in TL was cross-sectionally associated with higher odds of sarcopenia (OR = 1.31; 95% CI: 1.03-1.67) and prospectively with a higher incidence (RRR = 1.55; 95% CI: 1.06-2.25) and persistence (RRR = 1.50; 95% CI: 1.01-2.24) of sarcopenia.

CONCLUSIONS

Older adults with shorter TL had higher rates of incident and persistent sarcopenia. Implementation of interventions to delay the decline of TL in older adults is warranted. Further translational studies are needed to elucidate the effects of exercise or diet on DNA repair in the telomeric region and their associations with sarcopenia.

Leukocyte telomere length and sarcopenia-related traits: A bidirectional Mendelian randomization study

Accumulating evidence indicated that leukocyte telomere length (LTL) was related to sarcopenia. However, it is still not clear whether the association of changes in LTL with sarcopenia is likely to be causal, or could be explained by reverse causality. Thus, we carried on bidirectional Mendelian randomization (MR) and multivariable MR analyses to identify the causal relationship between LTL and sarcopenia-related traits. Summary-level data and independent variants used as instruments came from large genome-wide association studies of LTL (472,174 participants), appendicular lean mass (450,243 participants), low grip strength (256,523 participants), and walking pace (450,967 participants). We identified suggestive association of longer LTL with larger appendicular lean mass [odds ratio (OR) = 1.053; 95% confidence interval (CI), 1.009-1.099; P = 0.018], and causal association of longer LTL with a lower risk of low grip strength (OR = 0.915; 95% CI, 0.860-0.974; P = 0.005). In the reverse MR analysis, we also observed a positive causal association between walking pace and LTL (OR = 1.252; 95% CI, 1.121-1.397; P < 0.001). Similar results can be repeated in sensitivity analyses. While in the multivariable MR analysis, the estimate of the impact of walking pace on LTL underwent a transformation after adjusting for T2DM (OR = 1.141; 95%CI: 0.989-1.317; P = 0.070). The current MR analysis supported a causal relationship between shorter telomere length and both low muscle mass and strength. Additionally, walking pace may affect LTL through T2DM.

Telomere length as a marker of changes in body composition and fractures-an analysis of data from the NHANES 2001-2002

Purpose

There has been an association between changes in body composition, fracture incidence, and age in previous studies. Telomere length (TL) has been proposed as a biomarker of aging. However, the relationship between body composition, fractures, and TL has rarely been studied. Therefore, this study aimed to investigate the correlation between TL and body composition and fractures.Patients and methods: 20950 participants from the 2001-2002 National Health and Nutrition Examination Survey (NHANES) were included in the final analysis. In NHANES, body compositions were measured with DXA, and TL was determined with quantitative PCR. Correlation analysis of TL and body composition was conducted using multivariate weighted linear regression and logistic regression models.

Results

The results showed that TL positively correlated with bone mineral density (BMD) and bone mineral content (BMC) in most body parts. However, BMD and BMC were negatively connected with TL in the upper limbs and skull. Fat content was negatively associated with TL, while muscle content was positively linked to TL. In addition, TL's trend analysis results were consistent with the regression model when transformed from a continuous to a classified variable. An increase in TL was associated with a higher incidence of wrist fractures, while a decrease in spine fractures. The above correlation also has a certain degree of sex specificity.

Conclusion

Our study indicate that TL is associated with body composition as well as fractures, but further research is needed to confirm these contrasting associations in the skull, upper limbs, and wrists.

Aging, Physical Exercise, Telomeres, and Sarcopenia: A Narrative Review

Human aging is a gradual and adaptive process characterized by a decrease in the homeostatic response, leading to biochemical and molecular changes that are driven by hallmarks of aging, such as oxidative stress (OxS), chronic inflammation, and telomere shortening. One of the diseases associated with the hallmarks of aging, which has a great impact on functionality and quality of life, is sarcopenia. However, the relationship between telomere length, sarcopenia, and age-related mortality has not been extensively studied. Moderate physical exercise has been shown to have a positive effect on sarcopenia, decreasing OxS and inflammation, and inducing protective effects on telomeric DNA. This results in decreased DNA strand breaks, reduced OxS and IA, and activation of repair pathways. Higher levels of physical activity are associated with an apparent increase in telomere length. This review aims to present the current state of the art of knowledge on the effect of physical exercise on telomeric maintenance and activation of repair mechanisms in sarcopenia.

Lean body mass but not body fat mass is related with leukocyte telomere length in children

OBJECTIVES

The aim of this study was to investigate the relationship between body composition and leukocyte telomere length (LTL) in healthy Chinese children aged 6-11 years.

METHODS

This cross-sectional study enrolled 406 healthy children (175 girls and 231 boys). The relative telomere length in their peripheral blood leukocytes was determined via quantitative polymerase chain reaction. Dual-energy X-ray absorptiometry was used to determine body fat content and regional fat distribution, appendicular skeletal muscle mass (ASM), bone mineral density (BMD) and bone mineral content (BMC) at the total body (TB) and total body less head (TBLH) levels, and total body lean mass (TBLM) was then determined. ASM/height² (ASMI) was also calculated.

RESULTS

After adjusting for potential covariates, multiple linear regression analyses revealed that neither body fat content nor regional body fat distribution were significantly associated with LTL (β = -8.48 × 10^-6-1.44 × 10^-1, p = 0.227-0.959). However, ASM, ASMI, TB BMC/TB BMD, TBLH BMC/TBLH BMD and TBLM were positively associated with LTL (β = 8.95 × 10^-6-4.95 × 10^-1, p = 0.005-0.035). Moreover, analysis of covariance revealed there was a statistically significant dose-dependent positive association between LTL and ASM, TB BMC/BMD, TBLH BMC/BMD, and TBLM (p-trend = 0.002-0.025).

CONCLUSIONS

Skeletal muscle mass and bone mass but not body fat content or distribution were significantly associated with LTL in this pediatric population.

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.

Associations between leukocyte telomere length and osteosarcopenia in 20,400 adults aged 60 years and over: Data from the UK Biobank

PURPOSE

Two mechanisms implicated in telomere shortening are oxidative stress and inflammation, both of which are linked to bone and muscle loss suggesting a pathological link between telomere attrition and osteosarcopenia. Using older adults aged 60 years and over in the UK Biobank, we examined the association between leukocyte telomere length and osteosarcopenia.

METHODS

Baseline leukocyte telomere length was measured using a multiplex qPCR technique and expressed as the amount of the telomere amplification product (T) to that of a single-copy gene (S) (T/S ratio). Osteosarcopenia data was from the first imaging visit and defined by WHO criteria (femoral neck bone density T score ≤ -1) for osteopenia/osteoporosis plus either the EWGSOP2 (low appendicular lean mass/height² and low grip strength) or SDOC (low grip strength and slow walking pace) criteria for sarcopenia. Binary or multinomial logistic regression models were used to associate telomere length and osteosarcopenia or its components, adjusting for the covariates: age, sex, race, education, Townsend deprivation index, alcohol, smoking, BMI/weight, physical activity levels.

RESULTS

Among 20,400 older adults (mean age: 67.79 ± 4.9 years, 53% men), the prevalence of osteosarcopenia by EWGSOP2 (n = 96, 0.47%) or SDOC (n = 205, 1%) criteria was low at the first imaging visit (mean 8.82 years after baseline). Baseline telomere length was not associated with osteosarcopenia by EWGSOP2 (Relative Risk (RR): 1.00, 95% CI: 0.82-1.23 comparing osteosarcopenia to normal (non-osteopenic, non-osteoporotic, and non-sarcopenic) per Standard Deviation (SD) increase in telomere length) or SDOC (RR: 0.95, 95% CI: 0.83-1.09) criteria. Longer telomere length was associated with a lower risk of slow walking pace (Odds Ratio: 0.92, 95% CI: 0.87-0.99 per SD increase in telomere length, p = 0.021). Telomere length, however, was not associated with low grip strength, low bone density or low appendicular lean mass/height² (p > 0.05).

CONCLUSIONS

In this population-based study, telomere length was not associated with osteosarcopenia; however, slow walking pace was. Further studies are needed to reexamine this relationship, including a greater number of the oldest-old (≥75 years) where osteosarcopenia is more prevalent.

The Functional Role of Long Non-Coding RNA in Myogenesis and Skeletal Muscle Atrophy

Skeletal muscle is a pivotal organ in humans that maintains locomotion and homeostasis. Muscle atrophy caused by sarcopenia and cachexia, which results in reduced muscle mass and impaired skeletal muscle function, is a serious health condition that decreases life longevity in humans. Recent studies have revealed the molecular mechanisms by which long non-coding RNAs (lncRNAs) regulate skeletal muscle mass and function through transcriptional regulation, fiber-type switching, and skeletal muscle cell proliferation. In addition, lncRNAs function as natural inhibitors of microRNAs and induce muscle hypertrophy or atrophy. Intriguingly, muscle atrophy modifies the expression of thousands of lncRNAs. Therefore, although their exact functions have not yet been fully elucidated, various novel lncRNAs associated with muscle atrophy have been identified. Here, we comprehensively review recent knowledge on the regulatory roles of lncRNAs in skeletal muscle atrophy. In addition, we discuss the issues and possibilities of targeting lncRNAs as a treatment for skeletal muscle atrophy and muscle wasting disorders in humans.

Immunosenescence in Childhood Cancer Survivors and in Elderly: A Comparison and Implication for Risk Stratification

The population of childhood cancer survivors (CCS) has grown rapidly in recent decades. Although cured of their original malignancy, these individuals are at increased risk of serious late effects, including age-associated complications. An impaired immune system has been linked to the emergence of these conditions in the elderly and CCS, likely due to senescent immune cell phenotypes accompanied by low-grade inflammation, which in the elderly is known as "inflammaging." Whether these observations in the elderly and CCS are underpinned by similar mechanisms is unclear. If so, existing knowledge on immunosenescent phenotypes and inflammaging might potentially serve to benefit CCS. We summarize recent findings on the immune changes in CCS and the elderly, and highlight the similarities and identify areas for future research. Improving our understanding of the underlying mechanisms and immunosenescent markers of accelerated immune aging might help us to identify individuals at increased risk of serious health complications.

Intra-uterine effects on adult muscle strength

BACKGROUND

Maternal behaviors and exposures affect fetal growth and development. Smoking, malnutrition, sedentary behavior, and stress can each lead to fetal programming and intra-uterine growth restriction. As a result, tissue development may be impaired. Problems with muscle formation can lead to reductions in muscle performance throughout life. The purpose of this study was to determine if in utero effects on muscle mass, muscle function, or both are responsible for the relationship between size at birth and adult muscle strength.

STUDY DESIGN

One hundred adults (ages 18-40), who were singletons born at term (37-42 weeks), participated. Birth weight was adjusted for gestational age using neonatal growth reference data. Maximal voluntary contractions (MVC) of dominant and non-dominant handgrip, and right and left leg extension were measured. Linear regression analysis was used to determine the association between adjusted birth weight and muscle strength. Sex and lean body mass were covariates.

RESULTS

Dominant handgrip MVC increased by 1.533 kg per 1 SD increase in adjusted birth weight (p = 0.004). Lean body mass had a significant indirect effect on this relationship. The relationship between handgrip strength and adjusted birth weight was strongest among female subjects. No other muscle strength measures were significantly associated with adjusted birth weight.

CONCLUSIONS

Birth size was a significant predictor of handgrip strength in adulthood. Including lean body mass attenuated, but did not remove, the association. Thus, among individuals born to term, having a smaller-than-predicted birth size likely causes both reductions in muscle mass formation and decreased muscle function, ultimately impacting muscle strength in adulthood.

Age-related changes of human serum Sirtuin6 in adults

Background

Aging is a natural life process and with an aging population, age-related diseases (e.g. type 2 diabetes mellitus (T2DM), atherosclerosis-based cardiovascular diseases) are the primary mortality cause in older adults. Telomerase is often used as an aging biomarker. Detection and characterization of novel biomarkers can help in a more specific and sensitive identification of a person’s aging status. Also, this could help in age-related diseases early prevent, ultimately prolonging the population’s life span. Sirtuin 6 (Sirt6) - a member of the Sirtuins NAD⁺-dependent histone deacetylases family - is mainly intracellularly expressed, and is reported to be involved in the regulation of aging and aging-related diseases. Whether serum Sirt6 is correlated with aging and could be used as an aging biomarker is unknown. In the present study, we aimed to investigate the age-related Sirt6 changes in the serum of human adults.

Methods

Participants were divided into three groups according to age: 20–30 years (Young); 45–55 years (Middle-aged); and ≥ 70 years (Old). The Sirt6 and telomerase serum concentrations were determined by ELISA. The Sirt6 and human telomerase reverse transcriptase (hTERT) expression in vessels from amputated human lower limbs were analyzed using real-time quantitative PCR (RT-qPCR) and immunohistochemical staining. The relationships between variables were evaluated by Pearson correlation analysis.

Results

The Sirt6 and telomerase serum levels reduced with an increase in age. A similar tendency was observed for Sirt6 and hTERT in the vessel. Serum levels of Sirt6 were higher in females compared with males. Pearson’s regression analysis revealed that the Sirt6 serum level positively correlated with telomerase (r = 0.5743) and both were significantly negatively correlated with age (r = − 0.5830 and r = − 0.5993, respectively).

Conclusions

We reported a negative correlation between serum Sirt6 concentration and aging in human beings. Therefore, the Sirt6 serum level is a potential sex-specific aging marker.

A Systematic Review of the Association Between Muscular Fitness and Telomere Length Across the Adult Lifespan

This study aimed to systematically review the association between telomere length (TL) and muscular fitness. In October 2020, an articles search was applied to PubMed, Scopus, and Web of Science. Eligibility criteria included: cross-sectional, prospective, and experimental study design; outcomes included TL; results expressed the relationship between muscular fitness and TL; studies published in English, Portuguese, or Spanish. Nine studies were included in the review. Results from the four prospective studies are mixed. In one study, the changes in TL were associated with grip strength. Another study concluded that longer mid-life TL was associated with increased grip strength later in life. However, in the other two studies, the association between TL and sarcopenia was not strong. Nevertheless, longer TL was associated with a slower decline in grip strength in older people. From the four cross-sectional studies, three indicated that TL was associated with muscular fitness. On the other hand, in a study with powerlifters, TL remained within the range of values found in subjects with no history of regular strength training, supporting the notion that muscular fitness was not associated with TL. The cross-sectional and prospective studies showed that the relationship between TL and muscular fitness is not conclusive. It seems that there is a positive association between TL and muscular fitness in middle-aged and older adults. However, among younger adults, this relationship was not observed.

Midlife Leukocyte Telomere Length as an Indicator for Handgrip Strength in Late Life

BACKGROUND

Telomere attrition has been proposed as a hallmark of aging. We previously reported on the association between blood leukocyte telomere length (LTL) at midlife and risk of chronic diseases and mortality.

METHODS

In this study, we investigated the effect of midlife LTL and genetic proxies on 5 markers of aging outcomes, namely handgrip strength, timed up-and-go (TUG), Singapore-modified Mini-Mental State Examination (SM-MMSE) scores, anxiety, and depression indices, measured after a median 20-year follow-up in the Singapore Chinese Health Study (N = 9581).

RESULTS

We observed a significant association between midlife LTL and handgrip strength later in life (p = .004, padjust = .020), as well as a nominal significant association between midlife LTL and TUG later in life (p = .036, padjust = .180). The weighted Genetic Risk Score (wGRS) comprising 15 previously reported LTL reducing loci in East Asians was not significantly associated with handgrip strength. However, results from Structural Equation Modeling showed that the effect of this wGRS on handgrip strength was mediated through LTL (proportion of wGRS effect on handgrip strength mediated through LTL = 33.3%, p = .010).

CONCLUSIONS

Longer midlife LTL was associated with increased handgrip strength later in life.

Sarcopenia - Molecular mechanisms and open questions

Sarcopenia represents a muscle-wasting syndrome characterized by progressive and generalized degenerative loss of skeletal muscle mass, quality, and strength occurring during normal aging. Sarcopenia patients are mainly suffering from the loss in muscle strength and are faced with mobility disorders reducing their quality of life and are, therefore, at higher risk for morbidity (falls, bone fracture, metabolic diseases) and mortality. Several molecular mechanisms have been described as causes for sarcopenia that refer to very different levels of muscle physiology. These mechanisms cover e. g. function of hormones (e. g. IGF-1 and Insulin), muscle fiber composition and neuromuscular drive, myo-satellite cell potential to differentiate and proliferate, inflammatory pathways as well as intracellular mechanisms in the processes of proteostasis and mitochondrial function. In this review, we describe sarcopenia as a muscle-wasting syndrome distinct from other atrophic diseases and summarize the current view on molecular causes of sarcopenia development as well as open questions provoking further research efforts for establishing efficient lifestyle and therapeutic interventions.

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.

A research agenda for ageing in China in the 21st century (2nd edition): Focusing on basic and translational research, long-term care, policy and social networks

One of the key issues facing public healthcare is the global trend of an increasingly ageing society which continues to present policy makers and caregivers with formidable healthcare and socio-economic challenges. Ageing is the primary contributor to a broad spectrum of chronic disorders all associated with a lower quality of life in the elderly. In 2019, the Chinese population constituted 18 % of the world population, with 164.5 million Chinese citizens aged 65 and above (65+), and 26 million aged 80 or above (80+). China has become an ageing society, and as it continues to age it will continue to exacerbate the burden borne by current family and public healthcare systems. Major healthcare challenges involved with caring for the elderly in China include the management of chronic non-communicable diseases (CNCDs), physical frailty, neurodegenerative diseases, cardiovascular diseases, with emerging challenges such as providing sufficient dental care, combating the rising prevalence of sexually transmitted diseases among nursing home communities, providing support for increased incidences of immune diseases, and the growing necessity to provide palliative care for the elderly. At the governmental level, it is necessary to make long-term strategic plans to respond to the pressures of an ageing society, especially to establish a nationwide, affordable, annual health check system to facilitate early diagnosis and provide access to affordable treatments. China has begun work on several activities to address these issues including the recent completion of the of the Ten-year Health-Care Reform project, the implementation of the Healthy China 2030 Action Plan, and the opening of the National Clinical Research Center for Geriatric Disorders. There are also societal challenges, namely the shift from an extended family system in which the younger provide home care for their elderly family members, to the current trend in which young people are increasingly migrating towards major cities for work, increasing reliance on nursing homes to compensate, especially following the outcomes of the 'one child policy' and the 'empty-nest elderly' phenomenon. At the individual level, it is important to provide avenues for people to seek and improve their own knowledge of health and disease, to encourage them to seek medical check-ups to prevent/manage illness, and to find ways to promote modifiable health-related behaviors (social activity, exercise, healthy diets, reasonable diet supplements) to enable healthier, happier, longer, and more productive lives in the elderly. Finally, at the technological or treatment level, there is a focus on modern technologies to counteract the negative effects of ageing. Researchers are striving to produce drugs that can mimic the effects of 'exercising more, eating less', while other anti-ageing molecules from molecular gerontologists could help to improve 'healthspan' in the elderly. Machine learning, 'Big Data', and other novel technologies can also be used to monitor disease patterns at the population level and may be used to inform policy design in the future. Collectively, synergies across disciplines on policies, geriatric care, drug development, personal awareness, the use of big data, machine learning and personalized medicine will transform China into a country that enables the most for its elderly, maximizing and celebrating their longevity in the coming decades. This is the 2nd edition of the review paper (Fang EF et al., Ageing Re. Rev. 2015).

Association between appendicular skeletal muscle index and leukocyte telomere length in adults: A study from National Health and Nutrition Examination Survey (NHANES) 1999-2002

BACKGROUND

A higher body mass index (BMI) is associated with shorter telomeres. The loss of muscle mass with aging is associated with adverse outcomes. The appendicular skeletal muscle index (ASMI) is currently used to quantify muscle mass.

OBJECTIVE

We investigated the association of the ASMI with leukocyte telomere length in adult Americans.

METHODS

This cross-sectional study used the National Health and Nutrition Examination Survey (NHANES) 1999-2002 dataset. Body composition was measured by dual-energy X-ray absorptiometry. Low muscle mass was defined using sex-specific thresholds of the appendicular skeletal muscle mass index (ASMI). The telomere-to-single-copy gene ratio (T/S ratio) was converted to base pairs. Generalized linear models were performed to evaluate the association of ASMI with telomere length.

RESULTS

In multivariable adjustment regression models, higher ASMI was associated with longer telomeres in US adults (β = 70.2, P < 0.001, P trend<0.001). In participants with preserved muscle mass, the ASMI was related to longer telomere length (β = 75.1, P < 0.001), but not significantly in low muscle mass participants (β = 68.7, P = 0.30). Further subgroup analysis by a combination of age groups and muscle mass status showed positive association with young-preserved muscle mass (β = 82.6, P < 0.001), old-preserved muscle mass (β = 44.4, P = 0.12), young-low muscle mass (β = 135.4, P = 0.20), and old-low muscle mass (β = 52.7, P = 0.55). Because each additional year of chronological age was associated with telomeres that were 15.3 base pairs shorter, on average, this would equate to 5.4 fewer years of biological aging (82.6 ÷ 15.3) in the young-preserved muscle mass participants.

CONCLUSIONS

A higher ASMI is associated with longer telomeres. The prevention of skeletal muscle loss has the potential to delay telomere shortening and account for less biological aging.

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.

Telomere shortening is associated with poor physical performance in knee osteoarthritis

Telomere length is a hallmark characteristic of ageing and age-related diseases. Osteoarthritis (OA) is the most common cause of joint pain and physical disability in the elderly. Previous studies have revealed the role of telomere shortening in OA; however, the relationship between telomere length, muscle strength and physical performance in knee OA patients remains unknown. The aim of the present study was to investigate the association of telomere length and physical performance in patients with knee OA. A total of 202 patients with knee OA and 60 healthy controls were enrolled in the study. The quality of life was assessed using Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and Short Form Health Survey. The skeletal muscle mass was examined using bioelectrical impedance analysis, while the muscle strength was analyzed using hand grip force and isometric knee extension force. The physical performance of patients with knee OA was also investigated using gait speed, Timed up and go test (TUGT), Sit to stand test and 6-min walk test (6MWT). Blood leukocyte relative telomere length (RTL) was assessed using real time quantitative PCR. The mean blood leukocyte RTL in knee OA subjects was significantly lower compared with healthy controls (P<0.001). Knee OA patients with RTL values in the lowest quartile had a slow gait speed (P=0.006) and prolonged TUGT time (P=0.03). Multivariate regression analyses and multiple logistic regression analyses adjusted for age, sex, waist circumference, body mass index, fat mass, skeletal muscle index and the total WOMAC demonstrated that gait speed, TUGT and 6MWT were associated with longer RTL (P-trend<0.05). These findings suggested that poorer physical performance was associated with shorter RTL. Therefore, leukocyte telomere length and physical performance tests, especially gait speed, TUGT and 6MWT, could predict the health status and quality of life in patients with knee OA.

Short Telomere Length Is Related to Limitations in Physical Function in Elderly European Adults

The present study aims to explore the potential influence of leucocyte telomere length (LTL) on both a single indicator and a composite construct of physical functioning in a large European population of elderly men and women across diverse geographical locations. A total of 1,221 adults (65–79 years) were recruited from five European countries within the framework of NU-AGE study. The physical functioning construct was based on the 36-item Short Form Health Survey. Handgrip strength was used as a single indicator of muscle function and LTL was assessed using quantitative real-time PCR. Women had significantly longer (p < 0.05) LTL than men. Participants in Poland had significantly shorter LTL than in the other study centers, whereas participants in the Netherlands had significantly longer LTL than most of the other centers (p < 0.01). An analysis of LTL as a continuous outcome against physical functioning by using linear models revealed inconsistent findings. In contrast, based on an analysis of contrasting telomere lengths (first vs. fifth quintile of LTL), a significant odds ratio (OR) of 1.7 (95% CI: 1.1 – 2.6; p < 0.05) of having functional limitation was observed in those belonging to the first LTL quintile compared to the fifth. Interestingly, having the shortest LTL was still related to a higher likelihood of having physical limitation when compared to all remaining quintiles (OR: 1.5, 95% CI: 1.1 – 2.1; p < 0.05), even after adjustment by study center, age, sex, and overweight status. Collectively, our findings suggest that short LTL is an independent risk factor that accounts for functional decline in elderly European populations. The influence of LTL on functional limitation seems driven by the detrimental effect of having short telomeres rather than reflecting a linear dose-response relationship.

Premature Physiologic Aging as a Paradigm for Understanding Increased Risk of Adverse Health Across the Lifespan of Survivors of Childhood Cancer

The improvement in survival of childhood cancer observed across the past 50 years has resulted in a growing acknowledgment that simply extending the lifespan of survivors is not enough. It is incumbent on both the cancer research and the clinical care communities to also improve the health span of survivors. It is well established that aging adult survivors of childhood cancer are at increased risk of chronic health conditions, relative to the general population. However, as the first generation of survivors age into their 50s and 60s, it has become increasingly evident that this population is also at risk of early onset of physiologic aging. Geriatric measures have uncovered evidence of reduced strength and speed and increased fatigue, all components of frailty, among survivors with a median age of 33 years, which is similar to adults older than 65 years of age in the general population. Furthermore, frailty in survivors independently increased the risk of morbidity and mortality. Although there has been a paucity of research investigating the underlying biologic mechanisms for advanced physiologic age in survivors, results from geriatric populations suggest five biologically plausible mechanisms that may be potentiated by exposure to cancer therapies: increased cellular senescence, reduced telomere length, epigenetic modifications, somatic mutations, and mitochondrial DNA infidelity. There is now a critical need for research to elucidate the biologic mechanisms of premature aging in survivors of childhood cancer. This research could pave the way for new frontiers in the prevention of these life-changing outcomes.

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.

Recognition of a sequence: more growth before birth, longer telomeres at birth, more lean mass after birth

BACKGROUND

Telomere length at birth is a major determinant of telomere length in late adulthood. However, the prenatal setting of telomere length is poorly understood. Individuals born large from non-diabetic mothers are at lower risk for later-life disorders than those born small, a feature of their longer health span being a higher lean mass that provides more muscle strength and that is already present in infancy.

METHODS

At birth, we studied leukocyte telomere length (by quantitative polymerase chain reaction) in 103 small-for-gestational-age, appropriate-for-gestational-age or large-for-gestational-age (SGA, AGA or LGA) infants born after uncomplicated, term, singleton pregnancies. All infants were breastfed for ≥4 months. At 2 weeks and 12 months, body composition was assessed by dual X-ray absorptiometry.

RESULTS

Telomere lengths were shorter in SGA newborns and longer in LGA newborns than in AGA newborns (P < 0.001), also after adjustment for maternal age, pre-gestational body mass index, gestational weight gain and gestational age. Telomere length at birth associated (all P ≤ 0.001) to birthweight (r = 0.50) and to both lean mass (r = 0.43) and fat mass (r = 0.48) at age 2 weeks, but only to lean mass at 12 months (r = 0.51).

CONCLUSION

Higher weight and longer telomeres at birth are followed by more lean mass in late infancy. Relatively large, breastfed infants from non-diabetic mothers may become models of how to make a healthy start.

Associations of Leukocyte Telomere Length With Aerobic and Muscular Fitness in Young Adults

Decline in both telomere length and physical fitness over the life course may contribute to increased risk of several chronic diseases. The relationship between telomere length and aerobic and muscular fitness is not well characterized. We examined whether there are cross-sectional associations of mean relative leukocyte telomere length (LTL) with objective measures of aerobic fitness, muscle strength, and muscle endurance, using data on 31-year-old participants of the Northern Finland Birth Cohort 1966 (n = 4,952–5,205, varying by exposure-outcome analysis). Aerobic fitness was assessed by means of heart rate measurement following a standardized submaximal step test; muscular fitness was assessed by means of a maximal isometric handgrip strength test and a test of lower-back trunk muscle endurance. Longer LTL was associated with higher aerobic fitness and better trunk muscle endurance in models including adjustment for age, sex, body mass index, socioeconomic position, diet, smoking, alcohol consumption, physical activity level, and C-reactive protein. In a sex-stratified analysis, LTL was not associated with handgrip strength in either men or women. LTL may relate to aspects of physical fitness in young adulthood, but replication of these findings is required, along with further studies to help assess directions and causality in these associations.

Resistance training and redox homeostasis: Correlation with age-associated genomic changes

Regular physical activity is effective as prevention and treatment for different chronic conditions related to the ageing processes. In fact, a sedentary lifestyle has been linked to a worsening of cellular ageing biomarkers such as telomere length (TL) and/or specific epigenetic changes (e.g. DNA methylation), with increase of the propensity to aging-related diseases and premature death. Extending our previous findings, we aimed to test the hypothesis that 12 weeks of low frequency, moderate intensity, explosive-type resistance training (EMRT) may attenuate age-associated genomic changes. To this aim, TL, global DNA methylation, TRF2, Ku80, SIRT1, SIRT2 and global protein acetylation, as well as other proteins involved in apoptotic pathway (Bcl-2, Bax and Caspase-3), antioxidant response (TrxR1 and MnSOD) and oxidative damage (myeloperoxidase) were evaluated before and after EMRT in whole blood or peripheral mononuclear cells (PBMCs) of elderly subjects. Our findings confirm the potential of EMRT to induce an adaptive change in the antioxidant protein systems at systemic level and suggest a putative role of resistance training in the reduction of global DNA methylation. Moreover, we observed that EMRT counteracts the telomeres' shortening in a manner that proved to be directly correlated with the amelioration of redox homeostasis and efficacy of training regime, evaluated as improvement of both muscle's power/strength and functional parameters.

Effect of Angiotensin-Converting Enzyme Inhibitors on Physical Function in Elderly Subjects: A Systematic Review and Meta-Analysis

BACKGROUND

Sarcopenia has been accepted as a new geriatric syndrome, which will become a common and important public health challenge. And angiotensin-converting enzyme inhibitors (ACEIs) have been shown to improve exercise capacity in elderly without heart failure.

OBJECTIVES

To evaluate the effect of angiotensin-converting enzyme inhibitors (ACEIs) on physical function in elderly.

DATA SOURCES

The Cochrane Library, PubMed, EMBASE and Web of Science were searched.

ELIGIBILITY CRITERIA

All researches included were randomized controlled trials (RCTs) which compared any kind of ACEIs with placebo or other anti-hypertensives in elderly, and provided empirical data of grip strength and 6-min walk distance change from baseline.

STUDY APPRAISAL AND SYNTHESIS METHODS

Risk of bias was systematically assessed by using the Cochrane risk of bias tool. Data of grip strength and 6-min walk distance change from baseline were collected and mean differences (MDs) were calculated along with 95% CI (confidence interval) by using a random effects model.

RESULTS

In 3 RCTs including 337 elderly participants, ACEIs (n = 178) did not significantly improved 6-min walk distance (13.45, 95% CI: -16.71 to 43.61; P = 0.38) versus placebo or other antihypertensives (n = 159). In 3 RCTs including 499 elderly participants, grip strength was not significantly different (-0.67, 95% CI: -1.53 to 0.19; P = 0.12) between ACEIs (n = 260) and placebo or other antihypertensives (n = 239).

LIMITATIONS

There exists only 4 RCTs and the number of participants is limited. Pooling of data were from different trials including different participant characteristics. And intervention is not strictly consistent.

CONCLUSION

This study shows that ACEIs can not significantly improve walk distance or the age-related decline of muscle strength for older participants in clinical trials.

Longitudinal telomere length shortening and cognitive and physical decline in later life: The Lothian Birth Cohorts 1936 and 1921

Telomere length is hypothesised to be a biological marker of both cognitive and physical ageing. Here we measure telomere length, and cognitive and physical abilities at mean ages 70, 73 and 76 years in the Lothian Birth Cohort 1936 (LBC1936), and at mean ages 79, 87, 90 and 92 years in the Lothian Birth Cohort 1921 (LBC1921). We investigate whether telomere length change predicts change in cognitive and physical abilities. In LBC1936 telomere length decreased by an average of 65 base pairs per year and in LBC1921 by 69 base pairs per year. However, change in telomere length did not predict change in cognitive or physical abilities. This study shows that, although cognitive ability, walking speed, lung function and grip strength all decline with age, they do so independently of telomere length shortening.

Leukocyte telomere length is related to appendicular lean mass: cross-sectional data from the Berlin Aging Study II (BASE-II)

BACKGROUND

Age-related progressive loss of muscle mass is an increasing problem in our aging society, affecting physical ability, risk of falls, and need for health care. Telomere length has been recognized as a marker of biological age on the population level. The relation between muscle mass in advanced age and telomere length, however, has rarely been examined.

OBJECTIVE

We evaluated the relation between appendicular lean mass (ALM) and relative leukocyte telomere length (rLTL) in 1398 participants of the Berlin Aging Study II (mean ± SD age: 68.2 ± 3.7 y; 49.6% men).

DESIGN

rLTL was determined by real-time polymerase chain reaction. Lean mass was estimated by dual X-ray absorptiometry and examined as leg lean mass (LLM), ALM, and the ratio of ALM to body mass index (ALMBMI).

RESULTS

Weak, but highly significant (P < 0.001), correlations of rLTL with ALM (r = 0.248), ALMBMI (r = 0.254), and LLM (r = 0.263) were found. In the fully adjusted model that included age, BMI, low-grade inflammation, lifestyle factors, and morbidities as potential confounders, rLTL was associated with ALM (β = 1.11, SEM = 0.46, P = 0.017), LLM (β = 1.20, SEM = 0.36, P = 0.001), and ALMBMI (β = 0.04, SEM = 0.02, P = 0.013) in men and with LLM in women (β = 0.78, SEM = 0.35, P = 0.026).

CONCLUSIONS

Our results suggest that short telomeres may be a risk factor for lower ALM, particularly for low LLM. To confirm the association between telomere attrition and loss of LLM and ALMBMI, which are highly relevant for physical ability, further research in a longitudinal context is needed. The medical portion of this trial was registered in the German Clinical Trials Registry (http://drks-neu.uniklinik-freiburg.de/drks_web/navigate.do?navigationId=start) as DRKS00009277.

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.

Effect of intensive exercise in early adult life on telomere length in later life in men

A career as an elite-class male athlete seems to improve metabolic heath in later life and is also associated with longer life expectancy. Telomere length is a biomarker of biological cellular ageing and could thus predict morbidity and mortality. The main aim of this study was to assess the association between vigorous elite-class physical activity during young adulthood on later life leukocyte telomere length (LTL). The study participants consist of former male Finnish elite athletes (n = 392) and their age-matched controls (n = 207). Relative telomere length was determined from peripheral blood leukocytes by quantitative real-time polymerase chain reaction. Volume of leisure-time physical activity (LTPA) was self-reported and expressed in metabolic equivalent hours. No significant difference in mean age-adjusted LTL in late life (p = 0.845) was observed when comparing former male elite athletes and their age-matched controls. Current volume of LTPA had no marked influence on mean age-adjusted LTL (p for trend 0.788). LTL was inversely associated with age (p = 0.004).Our study findings suggest that a former elite athlete career is not associated with LTL later in life. Key pointsA career as an elite-class athlete is associated with improved metabolic health in late life and is associated with longer life expectancy.A career as an elite-class athlete during young adulthood was not associated with leukocyte telomere length in later life.Current volume of leisure-time physical activity did not influence telomere length in later life.