Biomarkers of healthy ageing: expectations and validation

Metabolite and protein associations with general health in the population-based CHRIS study

Identifying biomarkers able to discriminate individuals on different health trajectories is crucial to understand the molecular basis of age-related morbidity. We investigated multi-omics signatures of general health and organ-specific morbidity, as well as their interconnectivity. We examined cross-sectional metabolome and proteome data from 3,142 adults of the Cooperative Health Research in South Tyrol (CHRIS) study, an Alpine population study designed to investigate how human biology, environment, and lifestyle factors contribute to people's health over time. We had 174 metabolites and 148 proteins quantified from fasting serum and plasma samples. We used the Cumulative Illness Rating Scale (CIRS) Comorbidity Index (CMI), which considers morbidity in 14 organ systems, to assess health status (any morbidity vs. healthy). Omics-signatures for health status were identified using random forest (RF) classifiers. Linear regression models were fitted to assess directionality of omics markers and health status associations, as well as to identify omics markers related to organ-specific morbidity. Next to age, we identified 21 metabolites and 10 proteins as relevant predictors of health status and results confirmed associations for serotonin and glutamate to be age-independent. Considering organ-specific morbidity, several metabolites and proteins were jointly related to endocrine, cardiovascular, and renal morbidity. To conclude, circulating serotonin was identified as a potential novel predictor for overall morbidity.

Does diet influence aging? Evidence from animal studies

Nutrition profoundly influences the risk for many age-related diseases. Whether nutrition influences human aging biology directly is less clear. Studies in different animal species indicate that reducing food intake ("caloric restriction" [CR]) can increase lifespan and delay the onset of diseases and the biological hallmarks of aging. Obesity has been described as "accelerated aging" and therefore the lifespan and health benefits generated by CR in both aging and obesity may occur via similar mechanisms. Beyond calorie intake, studies based on nutritional geometry have shown that protein intake and the interaction between dietary protein and carbohydrates influence age-related health and lifespan. Studies where animals are calorically restricted by providing free access to diluted diets have had less impact on lifespan than those studies where animals are given a reduced aliquot of food each day and are fasting between meals. This has drawn attention to the role of fasting in health and aging, and exploration of the health effects of various fasting regimes. Although definitive human clinical trials of nutrition and aging would need to be unfeasibly long and unrealistically controlled, there is good evidence from animal experiments that some nutritional interventions based on CR, manipulating dietary macronutrients, and fasting can influence aging biology and lifespan.

Risk factors associated with weak and asymmetric handgrip strength in older Chinese adults

OBJECTIVES

This study sought to investigate the potential risk factors associated with weak and asymmetric handgrip strength (HGS) in older Chinese adults.

METHODS

A total of 2702 participants aged ≥65 years from the two waves of data (2011 and 2013) from the China Health and Retirement Longitudinal Study were analyzed. The highest recorded HGS values (Method A) or the average HGS values (Method B) for the dominant hand were used to compute the HGS asymmetry (nondominant HGS/dominant HGS out of 0.9-1.1) and HGS weakness (male <28 kg, female <18 kg). Risk factors associated with the weak and asymmetric HGS were identified by logistic regression analysis.

RESULTS

Risk factors associated with weak and asymmetric HGS of varying severity differed between the two methods. Both methods identified age and illiteracy as risk factors for weak HGS with 10%-20% asymmetry. Method A also identified speech impediment, stroke, and sleep duration as additional risk factors. Similarly, both methods identified age, illiteracy, primary school education and below, diabetes, and stroke as risk factors for weak HGS and asymmetry over 30.1%. Method B additionally identified a history of falls as a risk factor. However, apart from age, the risk factors for weak HGS with 20.1%-30% asymmetry differed between the two methods-Method A identified kidney disease, while Method B identified illiteracy and asthma.

CONCLUSIONS

The results revealed that risk factors associated with the abnormal HGS in older adults varied based on the methods used to define these conditions.

Progress in the study of aging marker criteria in human populations

The use of human aging markers, which are physiological, biochemical and molecular indicators of structural or functional degeneration associated with aging, is the fundamental basis of individualized aging assessments. Identifying methods for selecting markers has become a primary and vital aspect of aging research. However, there is no clear consensus or uniform principle on the criteria for screening aging markers. Therefore, we combine previous research from our center and summarize the criteria for screening aging markers in previous population studies, which are discussed in three aspects: functional perspective, operational implementation perspective and methodological perspective. Finally, an evaluation framework has been established, and the criteria are categorized into three levels based on their importance, which can help assess the extent to which a candidate biomarker may be feasible, valid, and useful for a specific use context.

Global scientific trends in healthy aging in the early 21st century: A data-driven scientometric and visualized analysis

Background

According to the World Health Organization (WHO), healthy aging is the process of developing and maintaining the functional capacity for health in old age. A rapidly growing number of research studies on healthy aging have been conducted worldwide. The purpose of this research work is to explore global scientific landscape of healthy aging research over the last 22 years.

Methods

Scientific publications on healthy aging from January 1, 2000 to October 11, 2022 were retrieved from the Web of Science Core Collection (WoSCC) on October 11, 2022. A total of 6420 publications were included in the scientometric analysis. VOSviewer (1.6.18) was used to conduct scientometric and visualized analysis.

Results

The publication growth rate was 35.68 from 2000 to 2021. The United States of America (USA) led in both productivity and citations. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA was prominent in terms of both the highest citation count and the highest average citation count. The National Institute on Aging (NIA) and Evans, Michele K. were the most influential organization and author, respectively. Research hotspots in healthy aging were identified based on the co-occurrence analysis of keywords: (1) physical activity and mental health of older adults; (2) diseases impacting the health and lifespan of older adults; and (3) neuroscience. Our analysis indicates that gut microbiota, loneliness, frailty, mitochondria and resilience were the emerging themes in healthy aging research.

Conclusions

The quantity of annual publications on healthy aging has rapidly increased over the past 22 years, especially during 2018-2021. This analysis identified the status, trends, hot topics, and frontiers of healthy aging research. These findings will help researchers quickly understand the global representation of healthy aging research, influence resource dissemination, promote international collaborations, guide policy formulation, and improve health services for older adults.

Evaluation of bone density and hand grip strength in the course of drug treatment for osteoporosis : A real-world study

BACKGROUND

The aim of this clinical investigation was to assess the physical performance in osteoporotic patients undergoing drug treatment (DT) for years by measuring hand grip strength (HGS) and bone mineral density (BMD). A further aim was to detect the time until the occurrence of vertebral fractures (VF) and influencing factors.

MATERIAL AND METHODS

The investigation comprised 346 persons (276 women, 70 men) aged on average 66.9 ± 10.7 years with confirmed osteoporosis (OP). Over a mean period of 1384 ± 727 days, OP was assessed every 2 years, including a bone densitometry by dual X‑ray absorptiometry and HGS measurement. In subgroups OP patients were analyzed with and without a bone density (BMD) increase, and with and without VFs.

RESULTS

Under DT, calcium and vitamin D substitution, the median T‑score improved in the entire group from -3.2 to -3.1 standard deviations (SD; p = 0.002). HGS was reduced (median) from 26 kg to 24 kg (p < 0.001). The median interval until the occurrence of VF was 2652 days (95% confidence interval [CI] 1825.2-3478.8 days) and 1461 days (95% CI 1246.5-1675.5, p < 0.001) in those with and without a BMD increase, respectively.

DISCUSSION

Guideline-based DT improves bone density and causes a longer interval without VF. The HGS falls independent of BMD. The association between bone and muscle in patients with a deterioration of the musculoskeletal system is known as osteosarcopenia. Early muscle exercises would be meaningful in this setting.

Relationship between age and handgrip strength: Proposal of reference values from infancy to senescence

Introduction

Measurement of hand grip strength (HGS) has been proposed as a key component of frailty and has also been suggested as a central biomarker of healthy aging and a powerful predictor of future morbidity and mortality.

Objectives

(a) To determine whether a nonlinear relationship model could improve the prediction of handgrip strength (HGS) compared to the linear model and (b) to propose percentiles to evaluate HGS according to age and sex for a regional population of Chile from infancy to senescence.

Methods

A cross-sectional descriptive study was developed in a representative sample of the Maule region (Chile). The volunteers amounted to 5,376 participants (2,840 men and 2,536 women), with an age range from 6 to 80 years old. Weight, height, HGS (right and left hand) according to age and sex were evaluated. Percentiles were calculated using the LMS method [(L (Lambda; asymmetry), M (Mu; median), and S (Sigma; coefficient of variation)].

Results and discussion

There were no differences in HGS from 6 to 11 years of age in both sexes; however, from 12 years of age onwards, males presented higher HGS values in both hands (p < 0.05). The linear regression between age with HGS showed values of R ² = 0.07 in males and R ² = 0.02 in females. While in the non-linear model (cubic), the values were: R ² = 0.50 to 0.51 in men and R ² = 0.26 in women. The percentiles constructed by age and sex were: P5, P15, P50, P85, and P95 by age range and sex. This study demonstrated that there is a nonlinear relationship between chronological age with HGS from infancy to senescence. Furthermore, the proposed percentiles can serve as a guide to assess and monitor upper extremity muscle strength levels at all stages of life.

[Impact of osteoporosis on physical performance parameters of middle-aged and elderly individuals-a cross-sectional study]

BACKGROUND

Osteoporosis (OP) in the elderly is accompanied by reduced muscle mass and reduced muscle strength, also known as sarcopenia. This results in functional limitations and a high risk of falls and injuries. The determination of physical performance parameters such as grip strength and trunk strength on the one hand, and balance abilities on the other, provide information about the individual's general neuromuscular condition and serve as an indicator of physical performance in the elderly. The extent to which previous osteoporotic vertebral fractures (VFs) restrict an individual's physical performance has not been adequately investigated yet.

MATERIAL AND METHODS

In total, 118 persons, with a mean age of 71.5 ± 9 years, participated in the clinical trial (ethics committee approval number A2020-0041). Patients were divided into an OP group (58 patients) and a control group (CG; 60 patients). OP patients with (VFs) and without vertebral fractures (0VFs) were viewed separately in the subgroup analysis. Data concerning physical status, including hand grip strength (HGS), the chair-rising test (CRT), tandem stance (TS), tandem gait (TG), and single-leg stance (SLS) were available for all patients. All data were analyzed using SPSS, Version 23.0.

RESULTS

No significant difference (p > 0.05) was registered between the OP and CG groups with regard of HGS, CRT, TG, TS, and SLS. In the subgroup analysis, OP patients with VFs had a lower HGS than OP patients without 0 VFx (VFs 24.3 ± 10.2 kg vs. 0 VFs 29.7 ± 9.5 kg, p = 0.026). TS was maintained longer by OP patients 0 VFs (VFs 7.8 ± 3.2 s vs. 0 VFs 9.5 ± 1.8 s, p = 0.008). The latter were also able to maintain their balance in TG over more numerous steps (VFs 4.8 ± 3.0 vs. 0 VFs 6.7 ± 2.4, p = 0.011). In a regression analysis, body size, gender, and age were shown to be independent factors influencing HGS (p < 0.001).

CONCLUSION

Patient age, constitution, and gender have a relevant influence on HGS, with baseline conditions after diagnosed OP at comparable levels in this age group. In a subgroup of OP patients with VFs, there is a close relationship between bone and muscle with an increasing deterioration of the musculoskeletal system. For prophylaxis of osteosarcopenia, early training seems reasonable.

Thresholds for clinical practice that directly link handgrip strength to remaining years of life: estimates based on longitudinal observational data

OBJECTIVE

Muscle strength is a powerful predictor of mortality that can quickly and inexpensively be assessed by measuring handgrip strength (HGS). What is missing for clinical practice, however, are empirically meaningful cut-off points that apply to the general population and that consider the correlation of HGS with gender and body height as well as the decline in HGS during processes of normal ageing. This study provides standardised thresholds that directly link HGS to remaining life expectancy (RLE), thus enabling practitioners to detect patients with an increased mortality risk early on.

DESIGN

Relying on representative observational data from the Health and Retirement Study, the HGS of survey participants was z-standardised by gender, age and body height. We defined six HGS groups based on cut-off points in SD; we use these as predictors in survival analyses with a 9-year follow-up and provide RLE by gender based on a Gompertz model for each HGS group.

PARTICIPANTS

8156 US American women and men aged 50-80 years.

MAIN OUTCOME MEASURES

Z-standardised HGS and all-cause mortality.

RESULTS

Even slight negative deviations in HGS from the reference group with [0.0 SD, 0.5 SD) have substantial effects on survival. RLE among individuals aged 60 years with standardised HGS of [-0.5 SD, 0.0 SD) is 3.0/1.4 years lower for men/women than for the reference group, increasing to a difference of 4.1/2.6 years in the group with HGS of [-1.0 SD, -0.5 SD). By contrast, we find no benefit of strong HGS related to survival.

CONCLUSIONS

HGS varies substantially with gender, age and body height. This confirms the importance of considering these heterogeneities when defining reference groups and risk thresholds. Moreover, survival appears to decrease at much higher levels of muscle strength than is assumed in previous literature, suggesting that medical practitioners should start to become concerned when HGS is slightly below that of the reference group.

Normative reference values of the handgrip strength for the Portuguese workers

Introduction

The active workforce is increasingly aging. However workload, as well as working time and intensity, sometimes remains unchanged. This can be an even more critical situation in older people, since occupational exposure associated with aging, will further reduce the muscle's ability to generate energy, which in turn facilitates the development of these age-related syndromes. This study aims to identify the normative values of handgrip strength for Portuguese workers in the automotive industry.

Methods

About 1225 employees were invited to participate in the study. The final sample consisted of 656 employees in the assembly area. The handgrip strength was measured in kilograms (kg) using the Jamar digital dynamometer. Sex-specific profiles of handgrip strength were designed by the Ordinary Least Square regression (OLS) analysis, where height, age, age squared, and height squared are entered into the models as determining factors of the maximum grip strength in both female and male groups.

Results

The peak mean values of handgrip strength in the group of women was 34 kg in the age group of 35–39 years, and in the group of men the peak mean was 52 kg in the age group of 25–34 years. The most pronounced decline in the female group appears in the age of 30–34 years of about 4 kg and the male group the decline occurs at 2kg below the peak force, in the age group of 40–57 year-olds. This study used a cut-off at 2 SD below by the sex-specific peak mean.

Conclusion

Normative values can help delineate the career path of workers because they portray risk values according to age, height, and gender. The normative values assist health and engineering professionals and ergonomists in adjusting task demands to the morphological and strength characteristics of the workers.

Improving nutrition to support healthy ageing: what are the opportunities for intervention?

Alongside declining activity levels, energy needs fall in older age and eating less is expected. However, as total food consumption declines, intakes of many nutrients are also likely to fall; while energy requirements may be met, other nutrient needs may not. Although this highlights the importance of nutrient-dense foods and overall diet quality in older age to ensure nutrient intakes are sufficient, maintaining or increasing diet quality may be difficult at a time when food access and preparation are becoming more challenging, and diets may be more monotonous. Poor nutrition, even in developed settings, is common. Older malnourished adults are more likely to have poorer health outcomes, longer hospital stays and increased mortality. Thus, apart from the evident personal costs, the economic burden of disease-related malnutrition is significant, and effective preventive strategies to promote good nutrition among older populations are needed. In particular, there is a need for wider recognition of malnutrition risk among older adults, including implementation of routine screening of nutritional status and early diagnosis. Design of future interventions to support older community-dwelling adults requires a clear understanding of the personal and contextual influences that affect patterns of food choice and consumption, including consideration of the importance of social and psychological factors. In addition, there are opportunities to intervene earlier in the lifecourse; the most effective preventive efforts to promote good nutrition in older age may need to start ahead of age-related changes in physiology and function, including younger adulthood and at the retirement transition.

The risks of biomarker-based epidemiology: Associations of circulating calcium levels with age, mortality, and frailty vary substantially across populations

Recent studies have shown contradictory associations between calcium levels and health outcomes. We suspected these conflicting results were the consequence of more general issues with how biomarkers are analyzed in epidemiological studies, particularly in the context of aging. To demonstrate the risks of typical analyses, we used three longitudinal aging cohort studies and their demographic subsets to analyze how calcium levels change with age and predict risk of mortality and frailty. We show that calcium levels either increase or decrease with age depending on the population, and positively or negatively predict frailty depending on the population and analysis; both age and frailty results showed substantial heterogeneity. Mortality analyses revealed few significant associations but were likely underpowered. Variation in population composition (demographics, diseases, diet, etc.) leads to contradictory findings in the literature for calcium and likely for other biomarkers. Epidemiological studies of biomarkers are particularly sensitive to population composition both because biomarkers generally have non-linear and often non-monotonic relationships with other key variables, notably age and health outcomes, and because there is strong interdependence among biomarkers, which are integrated into complex regulatory networks. Consequently, most biomarkers have multiple physiological roles and are implicated in multiple pathologies. We argue that epidemiological studies of aging using biomarkers must account for these factors, and suggest methods to do this.

Therapeutic Manipulation of Ageing: Repurposing Old Dogs and Discovering New Tricks

Ageing is a leading risk factor for many debilitating diseases. While age-related diseases have been the subject of over a century of intense investigation, until recently, physiological ageing was considered unavoidable. Pharmacological and genetic studies have since shown that ageing is a malleable process and that its abrogation can prevent its associated diseases. This review summarises a sample of the most promising efforts to deliver the products of ageing research to the clinic. Current efforts include the use of clinically approved drugs that have since been repurposed, as well as the development of novel therapeutics, to target ageing. Furthermore, ongoing research has sought reliable biomarkers of ageing that will accelerate the development of such therapeutics. Development of these technologies will improve quality of late-life and help relieve the enormous stress placed on state healthcare systems by a rapidly ageing global population. Thus, for both medical and socioeconomic reasons, it is imperative that ageing is made to yield to intervention.

Strong or Weak Handgrip? Normative Reference Values for the German Population across the Life Course Stratified by Sex, Age, and Body Height

Handgrip strength is an important biomarker of healthy ageing and a powerful predictor of future morbidity and mortality both in younger and older populations. Therefore, the measurement of handgrip strength is increasingly used as a simple but efficient screening tool for health vulnerability. This study presents normative reference values for handgrip strength in Germany for use in research and clinical practice. It is the first study to provide normative data across the life course that is stratified by sex, age, and body height. The study used a nationally representative sample of test participants ages 17–90. It was based on pooled data from five waves of the German Socio-Economic Panel (2006–2014) and involved a total of 11,790 persons living in Germany (providing 25,285 observations). Handgrip strength was measured with a Smedley dynamometer. Results showed that peak mean values of handgrip strength are reached in men’s and women’s 30s and 40s after which handgrip strength declines in linear fashion with age. Following published recommendations, the study used a cut-off at 2 SD below the sex-specific peak mean value across the life course to define a ‘weak grip’. Less than 10% of women and men aged 65–69 were classified as weak according to this definition, shares increasing to about half of the population aged 80–90. Based on survival analysis that linked handgrip strength to a relevant outcome, however, a ‘critically weak grip’ that warrants further examination was estimated to commence already at 1 SD below the group-specific mean value.

Employing biomarkers of healthy ageing for leveraging genetic studies into human longevity

Genetic studies have thus far identified a limited number of loci associated with human longevity by applying age at death or survival up to advanced ages as phenotype. As an alternative approach, one could first try to identify biomarkers of healthy ageing and the genetic variants associated with these traits and subsequently determine the association of these variants with human longevity. In the present study, we used this approach by testing whether the 35 baseline serum parameters measured in the Leiden Longevity Study (LLS) meet the proposed criteria for a biomarker of healthy ageing. The LLS consists of 421 families with long-lived siblings of European descent, who were recruited together with their offspring and the spouses of the offspring (controls). To test the four criteria for a biomarker of healthy ageing in the LLS, we determined the association of the serum parameters with chronological age, familial longevity, general practitioner-reported general health, and mortality. Out of the 35 serum parameters, we identified glucose, insulin, and triglycerides as biomarkers of healthy ageing, meeting all four criteria in the LLS. We subsequently showed that the genetic variants previously associated with these parameters are significantly enriched in the largest genome-wide association study for human longevity. In conclusion, we showed that biomarkers of healthy ageing can be used to leverage genetic studies into human longevity. We identified several genetic variants influencing the variation in glucose, insulin and triglycerides that contribute to human longevity.

Living Long and Well: Prospects for a Personalized Approach to the Medicine of Ageing

Research into ageing and its underlying molecular basis enables us to develop and implement targeted interventions to ameliorate or cure its consequences. However, the efficacy of interventions often differs widely between individuals, suggesting that populations should be stratified or even individualized. Large-scale cohort studies in humans, similar systematic studies in model organisms as well as detailed investigations into the biology of ageing can provide individual validated biomarkers and mechanisms, leading to recommendations for targeted interventions. Human cohort studies are already ongoing, and they can be supplemented by in silico simulations. Systematic studies in animal models are made possible by the use of inbred strains or genetic reference populations of mice. Combining the two, a comprehensive picture of the various determinants of ageing and 'health span' can be studied in detail, and an appreciation of the relevance of results from model organisms to humans is emerging. The interactions between genotype and environment, particularly the psychosocial environment, are poorly studied in both humans and model organisms, presenting serious challenges to any approach to a personalized medicine of ageing. To increase the success of preventive interventions, we argue that there is a pressing need for an individualized evaluation of interventions such as physical exercise, nutrition, nutraceuticals and calorie restriction mimetics as well as psychosocial and environmental factors, separately and in combination. The expected extension of the health span enables us to refocus health care spending on individual prevention, starting in late adulthood, and on the brief period of morbidity at very old age.

Inflammation, But Not Telomere Length, Predicts Successful Ageing at Extreme Old Age: A Longitudinal Study of Semi-supercentenarians

To determine the most important drivers of successful ageing at extreme old age, we combined community-based prospective cohorts: Tokyo Oldest Old Survey on Total Health (TOOTH), Tokyo Centenarians Study (TCS) and Japanese Semi-Supercentenarians Study (JSS) comprising 1554 individuals including 684 centenarians and (semi-)supercentenarians, 167 pairs of centenarian offspring and spouses, and 536 community-living very old (85 to 99 years). We combined z scores from multiple biomarkers to describe haematopoiesis, inflammation, lipid and glucose metabolism, liver function, renal function, and cellular senescence domains. In Cox proportional hazard models, inflammation predicted all-cause mortality with hazard ratios (95% CI) 1.89 (1.21 to 2.95) and 1.36 (1.05 to 1.78) in the very old and (semi-)supercentenarians, respectively. In linear forward stepwise models, inflammation predicted capability (10.8% variance explained) and cognition (8(.)6% variance explained) in (semi-)supercentenarians better than chronologic age or gender. The inflammation score was also lower in centenarian offspring compared to age-matched controls with Δ (95% CI) = - 0.795 (- 1.436 to - 0.154). Centenarians and their offspring were able to maintain long telomeres, but telomere length was not a predictor of successful ageing in centenarians and semi-supercentenarians. We conclude that inflammation is an important malleable driver of ageing up to extreme old age in humans.

Low ALT blood levels predict long-term all-cause mortality among adults. A historical prospective cohort study

BACKGROUND

Increased blood levels of alanine amino transferase (ALT, also known as SGPT; serum glutamic pyruvic transaminase) serve as a marker of liver injury by various mechanisms. Less is known about the clinical implications associated with low-normal ALT levels. Previous studies showed low ALT levels to be associated with poor long-term outcomes among elderlies, serving as a biomarker for increased incidence of frailty and subsequent risk of mortality. However, it has not been determined yet whether low-normal ALT values might be predictive of frailty and mortality in younger, middle-aged adults.

METHODS

We conducted a historical prospective cohort analysis.

RESULTS

A total of 23,506 adults with ALT levels within the normal range, at the mean age of 48 ± 11 years, participating in an annual screening program for preventive medicine, were followed-up for a median period of 8.5 years during which 638 died. Low-normal ALT values (serum ALT activity <17IU/L) were found to be predictive for increased risk of all-cause mortality (HR=1.6; 95% CI 1.34-1.92; p<0.001). Statistically significant correlation was demonstrated even after applying a multifactorial model correction for age, gender, eGFR, low albumin, arterial hypertension, diabetes mellitus and ischemic heart disease.

CONCLUSIONS

We suggest that low-normal ALT values may serve as an independent predictive marker for increased long-term mortality in middle-aged adults.