Grip strength is inversely associated with DNA methylation age acceleration

Longitudinal relationship between grip strength and cognitive function in a European population older than 50 years: A cross-lagged panel model

OBJECTIVES

The aim of this study was to investigate the dynamic longitudinal relationship between grip strength and cognitive function.

METHODS

6175 participants aged ≥50 years were included in the study using three waves of follow-up data from the Survey of Health, Ageing, and Retirement in Europe in 2015 (T1), 2017 (T2) and 2019 (T3). Cognitive function was assessed using numeracy, verbal fluency, immediate recall, delayed recall and total. The cross-lagged panel model was used for analysis.

RESULTS

There was a correlation between grip strength and cognitive function. Standardized path coefficient from numeracy T1 to grip strength T2 was 0.017 (p = 0.003), and from numeracy T2 to grip strength T3 was 0.014 (p = 0.012). Standardized path coefficient from grip strength T1 to numeracy T2 was 0.096 (p < 0.001), and from grip strength T2 to numeracy T3 was 0.113 (p < 0.001). Other indicators of cognitive function had similar relationships with grip strength.

CONCLUSIONS

The study found a statistically significant longitudinal and bidirectional relationship between grip strength and cognitive function in a sample of people aged ≥50 years from several European countries.

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.

Mediation role of DNA methylation in association between handgrip strength and cognitive function in monozygotic twins

Handgrip strength is a crucial indicator to monitor the change of cognitive function over time, but its mechanism still needs to be further explored. We sampled 59 monozygotic twin pairs to explore the potential mediating effect of DNA methylation (DNAm) on the association between handgrip strength and cognitive function. The initial step was the implementation of an epigenome-wide association analysis (EWAS) in the study participants, with the aim of identifying DNAm variations that are associated with handgrip strength. Following that, we conducted an assessment of the mediated effect of DNAm by the use of mediation analysis. In order to do an ontology enrichment study for CpGs, the GREAT program was used. There was a significant positive association between handgrip strength and cognitive function (β = 0.194, P < 0.001). The association between handgrip strength and DNAm of 124 CpGs was found to be statistically significant at a significance level of P < 1 × 10-4. Fifteen differentially methylated regions (DMRs) related to handgrip strength were found in genes such as SNTG2, KLB, CDH11, and PANX2. Of the 124 CpGs, 4 within KRBA1, and TRAK1 mediated the association between handgrip strength and cognitive function: each 1 kg increase in handgrip strength was associated with a potential decrease of 0.050 points in cognitive function scores, mediated by modifications in DNAm. The parallel mediating effect of these 4 CpGs was -0.081. The presence of DNAm variation associated with handgrip strength may play a mediated role in the association between handgrip strength and cognitive function.

Uncovering clinical rehabilitation technology trends: field observations, mixed methods analysis, and data visualization

Objective

To analyze real-world rehabilitation technology (RT) use, with a view toward enhancing RT development and adoption.

Design

A convergent, mixed-methods study using direct field observations, semi-structured templates, and summative content analysis.

Setting

Ten neurorehabilitation units in a single health system.

Participants

3 research clinicians (1OT, 2PTs) observed ∼60 OTs and 70 PTs in inpatient; ∼18 OTs and 30 PTs in outpatient.

Interventions

Not applicable.

Main Outcome Measures

Characteristics of RT, time spent setting up and using RT, and clinician behaviors.

Results

90 distinct devices across 15 different focus areas were inventoried. 329 RT-uses were documented over 44 hours with 42% of inventoried devices used. RT was used more during interventions (72%) than measurement (28%). Intervention devices used frequently were balance/gait (39%), strength/endurance (30%), and transfer/mobility training (16%). Measurement devices were frequently used to measure vitals (83%), followed by grip strength (7%), and upper extremity function (5%). Device characteristics were predominately AC-powered (56%), actuated (57%), monitor-less (53%), multi-use (68%), and required little familiarization (57%). Set-up times were brief (mean ± SD = 3.8±4.21 and 0.8±1.3 for intervention and measurement, respectively); more time was spent with intervention RT (25.6±15) than measurement RT (7.3±11.2). RT nearly always involved verbal instructions (72%) with clinicians providing more feedback on performance (59.7%) than on results (30%). Therapists' attention was split evenly between direct attention towards the patient during clinician treatment (49.7%) and completing other tasks such as documentation (50%).

Conclusions

Even in a tech-friendly hospital, majority of available RT were observed un-used, but identifying these usage patterns is crucial to predict eventual adoption of new designs from earlier stages of RT development. An interactive data visualization page supplement is provided to facilitate this study.

Quality of life and socio-demographic factors associated with nutritional risk in Brazilian community-dwelling individuals aged 80 and over: cluster analysis and ensemble methods

Introduction

The aim of the present study was to use cluster analysis and ensemble methods to evaluate the association between quality of life, socio-demographic factors to predict nutritional risk in community-dwelling Brazilians aged 80 and over.

Methods

This cross-sectional study included 104 individuals, both sexes, from different community locations. Firstly, the participants answered the sociodemographic questionnaire, and were sampled for anthropometric data. Subsequently, the Mini-Mental State Examination (MMSE) was applied, and Mini Nutritional Assessment Questionnaire (MAN) was used to evaluate their nutritional status. Finally, quality of life (QoL) was assessed by a brief version of World Health Organizations' Quality of Life (WHOQOL-BREF) questionnaire and its older adults' version (WHOQOL-OLD).

Results

The K-means algorithm was used to identify clusters of individuals regarding quality-of-life characteristics. In addition, Random Forest (RF) and eXtreme Gradient Boosting (XGBoost) algorithms were used to predict nutritional risk. Four major clusters were derived. Although there was a higher proportion of individuals aged 80 and over with nutritional risk in cluster 2 and a lower proportion in cluster 3, there was no statistically significant association. Cluster 1 showed the highest scores for psychological, social, and environmental domains, while cluster 4 exhibited the worst scores for the social and environmental domains of WHOQOL-BREF and for autonomy, past, present, and future activities, and intimacy of WHOQOL-OLD.

Conclusion

Handgrip, household income, and MMSE were the most important predictors of nutritional. On the other hand, sex, self-reported health, and number of teeth showed the lowest levels of influence in the construction of models to evaluate nutritional risk. Taken together, there was no association between clusters based on quality-of-life domains and nutritional risk, however, predictive models can be used as a complementary tool to evaluate nutritional risk in individuals aged 80 and over.

Circulating Neurofilament Light Chain Levels Increase with Age and Are Associated with Worse Physical Function and Body Composition in Men but Not in Women

This study aimed to assess the relationship between age-related changes in Neurofilament Light Chain (NFL), a marker of neuronal function, and various factors including muscle function, body composition, and metabolomic markers. The study included 40 participants, aged 20 to 85 years. NFL levels were measured, and muscle function, body composition, and metabolomic markers were assessed. NFL levels increased significantly with age, particularly in men. Negative correlations were found between NFL levels and measures of muscle function, such as grip strength, walking speed, and chair test performance, indicating a decline in muscle performance with increasing NFL. These associations were more pronounced in men. NFL levels also negatively correlated with muscle quality in men, as measured by 50 kHz phase angle. In terms of body composition, NFL was positively correlated with markers of fat mass and negatively correlated with markers of muscle mass, predominantly in men. Metabolomic analysis revealed significant associations between NFL levels and specific metabolites, with gender-dependent relationships observed. This study provides insights into the relationship between circulating serum NFL, muscle function, and aging. Our findings hint at circulating NFL as a potential early marker of age-associated neurodegenerative processes, especially in men.

Associations of pyrethroid exposure with skeletal muscle strength and mass

This study aimed to examine the associations of pyrethroid exposure with handgrip strength and skeletal muscle mass and potential modification effects in US adults. The data from the National Health and Nutrition Examination Survey was used. Handgrip strength was determined with a handgrip dynamometer, and we quantified muscle mass by using the appendicular skeletal muscle index (ASMI). Urinary 3-Phenoxybenzoic Acid (3-PBA), a validated biomarker for pyrethroid exposure, was used in the primary analysis. After adjusting for other covariates, participants exposed to the highest tertile of 3-PBA exposure had significantly lower handgrip strength (β = -1.88, 95% CI: -3.29, -0.23, P = 0.026) than those exposed to the lowest tertile of 3-PBA. Similarly, the 3-PBA exposure was marginally significantly associated with ASMI (Tertile 3 vs. Tertile 1: β = -0.07, 95% CI: -0.14, -0.01, P = 0.056). Significant interactions were found between 3-PBA and body mass index (BMI) on handgrip strength and ASMI (P interaction < 0.05), which indicated a potential moderation effect of BMI on the associations. In conclusion, pyrethroid exposure was adversely associated with handgrip strength and skeletal muscle mass, especially in overweight and obese populations. Further studies are warranted to confirm our results and to explore the potential mechanisms.

Biomarkers of aging through the life course: A Recent Literature Update

Purpose of review

The development of biomarkers of aging has greatly advanced epidemiological studies of aging processes. However, much debate remains on the timing of aging onset and the causal relevance of these biomarkers. In this review, we discuss the most recent biomarkers of aging that have been applied across the life course.

Recent findings

The most recently developed aging biomarkers that have been applied across the life course can be designated into three categories: epigenetic clocks, epigenetic markers of chronic inflammation, and mitochondrial DNA copy number. While these have been applied at different life stages, the development, validation, and application of these markers has been largely centered on populations of older adults. Few studies have examined trajectories of aging biomarkers across the life course. As the wealth of molecular and biochemical data increases, emerging biomarkers may be able to capture complex and system-specific aging processes. Recently developed biomarkers include novel epigenetic clocks; clocks based on ribosomal DNA, transcriptomic profiles, proteomics, metabolomics, and inflammatory markers; clonal hematopoiesis of indeterminate potential gene mutations; and multi-omics approaches.

Summary

Attention should be placed on aging at early and middle life stages to better understand trajectories of aging biomarkers across the life course. Additionally, novel biomarkers will provide greater insight into aging processes. The specific mechanisms of aging reflected by these biomarkers should be considered when interpreting results.

Pain interference mediates the association between epigenetic aging and grip strength in middle to older aged males and females with chronic pain

Introduction

Chronic pain is one of the leading causes of disability that may accelerate biological aging and reduce physical function. Epigenetic clocks provide an estimate of how the system ages and can predict health outcomes such as physical function. Physical function declines may be attributed to decreases in muscle quality due to disuse that can be measured quickly and noninvasively using grip strength. The purpose of this study was to explore the associations among self-reported pain, grip strength, and epigenetic aging in those with chronic pain.

Methods

Participants (57.91 ± 8.04 years) completed pain questionnaires, a blood draw and hand grip strength task. We used an epigenetic clock previously associated with knee pain (DNAmGrimAge), and used the subsequent difference of predicted epigenetic age from chronological age (DNAmGrimAge-Difference).

Results

Exploratory pathway analyses revealed that pain intensity mediated the association between DNAmGrimAge-difference and handgrip strength in males only (β = -0.1115; CI [-0.2929, -0.0008]) and pain interference mediated the association between DNAmGrimAge-difference and handgrip strength in males β = -0.1401; CI [-0.3400, -0.0222]), and females (β = -0.024; CI [-0.2918, -0.0020]).

Discussion

Chronic knee pain may accelerate epigenetic aging processes that may influence handgrip strength in older age adults. Chronic pain could be a symptom of the aging body thus contributing to declines in musculoskeletal function in later life.

A molecular signature defining exercise adaptation with ageing and in vivo partial reprogramming in skeletal muscle

Exercise promotes functional improvements in aged tissues, but the extent to which it simulates partial molecular reprogramming is unknown. Using transcriptome profiling from (1) a skeletal muscle-specific in vivo Oct3/4, Klf4, Sox2 and Myc (OKSM) reprogramming-factor expression murine model; (2) an in vivo inducible muscle-specific Myc induction murine model; (3) a translatable high-volume hypertrophic exercise training approach in aged mice; and (4) human exercise muscle biopsies, we collectively defined exercise-induced genes that are common to partial reprogramming. Late-life exercise training lowered murine DNA methylation age according to several contemporary muscle-specific clocks. A comparison of the murine soleus transcriptome after late-life exercise training to the soleus transcriptome after OKSM induction revealed an overlapping signature that included higher JunB and Sun1. Also, within this signature, downregulation of specific mitochondrial and muscle-enriched genes was conserved in skeletal muscle of long-term exercise-trained humans; among these was muscle-specific Abra/Stars. Myc is the OKSM factor most induced by exercise in muscle and was elevated following exercise training in aged mice. A pulse of MYC rewired the global soleus muscle methylome, and the transcriptome after a MYC pulse partially recapitulated OKSM induction. A common signature also emerged in the murine MYC-controlled and exercise adaptation transcriptomes, including lower muscle-specific Melusin and reactive oxygen species-associated Romo1. With Myc, OKSM and exercise training in mice, as well habitual exercise in humans, the complex I accessory subunit Ndufb11 was lower; low Ndufb11 is linked to longevity in rodents. Collectively, exercise shares similarities with genetic in vivo partial reprogramming. KEY POINTS: Advances in the last decade related to cellular epigenetic reprogramming (e.g. DNA methylome remodelling) toward a pluripotent state via the Yamanaka transcription factors Oct3/4, Klf4, Sox2 and Myc (OKSM) provide a window into potential mechanisms for combatting the deleterious effects of cellular ageing. Using global gene expression analysis, we compared the effects of in vivo OKSM-mediated partial reprogramming in skeletal muscle fibres of mice to the effects of late-life murine exercise training in muscle. Myc is the Yamanaka factor most induced by exercise in skeletal muscle, and so we compared the MYC-controlled transcriptome in muscle to Yamanaka factor-mediated and exercise adaptation mRNA landscapes in mice and humans. A single pulse of MYC is sufficient to remodel the muscle methylome. We identify partial reprogramming-associated genes that are innately altered by exercise training and conserved in humans, and propose that MYC contributes to some of these responses.