Genome-wide meta-analysis of muscle weakness identifies 15 susceptibility loci in older men and women

Association between the sarcopenia-related traits and Parkinson's disease: A bidirectional two-sample Mendelian randomization study

OBJECTIVE

To explore the causal association between sarcopenia-related traits and Parkinson's disease by Mendelian randomization (MR) approach.

METHODS

A genome-wide association study (GWAS) of sarcopenia-related traits was done at the UK Biobank (UKB). The traits were appendicular lean mass, low hand grip strength (including the European Working Group on Sarcopenia in Older People (EWGSOP) and the Foundation for the National Institutes of Health (FNIH) criteria and usual walking pace. The International Parkinson's Disease Genomics Consortium (IPDGC) gave us GWAS data for Parkinson's disease (PD). We used three different types of MR analyses: including Inverse-variance weighted (IVW), Mendelian randomized Egger regression (MR-Egger), and weighted median methods (both weighted and simple modes).

RESULTS

The MR analysis showed that low hand grip strength was negatively associated with the risk of developing Parkinson's disease, including EWGSOP criterion (odds ratio (OR) = 0.734; 95% confidence interval (CI) = 0.575-0.937, P = 0.013) and FNIH criterion (OR = 0.619; 95% CI = 0.419-0.914, P = 0.016), and usual walking pace was also a risk factor for Parkinson's disease (OR = 3.307, 95% CI = 1.277-8.565, P = 0.014).

CONCLUSIONS

In European population, low hand grip strength is negatively associated with the risk of developing Parkinson's disease, and usual walking pace is also a risk factor for Parkinson's disease. Further exploration of the potential genetic mechanisms underlying hand grip strength and Parkinson's disease and the potential relationship between walking pace, balance, and falls in Parkinson's patients may help to reduce the burden of sarcopenia and Parkinson's disease.

Mendelian randomization study on association between grip strength and BMD in different age groups

INTRODUCTION

This study aimed to use the Mendelian randomization study method to verify the causal relationship between grip strength and bone mineral density (BMD) in different ages and different parts of the body.

MATERIALS AND METHODS

The analysis was based on pooled data from genome-wide association studies (GWAS). Hand grip strength (right) was used as the exposure variable and total body bone mineral density (BMD) of different age groups was used as the outcome variable. Single-nucleotide polymorphisms highly correlated with exposure variables were used as instrumental variables. The inverse variance weighted (IVW) method was used as the primary analysis method, and the Mendelian randomization Egger (MR-Egger) regression and weighted median methods were used as supplementary evidence for the IVW results. Horizontal pleiotropy and heterogeneity tests were conducted to ensure the stability of the results.

RESULTS

Analyzing the GWAS data on osteoporosis as the outcome variable, the IVW analysis showed that osteoporosis risk was associated with decreased grip strength in the 45-60 age group and the risk of declining lumbar spine BMD was associated with decreased grip strength. However, there was no significant correlation between the risk of osteoporosis in other age groups and changes in grip strength.

CONCLUSION

A causal relationship exists between decreased grip strength and osteoporosis risk in people aged 45-60 years. The risk of BMD declining in the lumbar spine was associated with reduced grip strength.

Impaired skeletal muscle regeneration in diabetes: From cellular and molecular mechanisms to novel treatments

Diabetes represents a major public health concern with a considerable impact on human life and healthcare expenditures. It is now well established that diabetes is characterized by a severe skeletal muscle pathology that limits functional capacity and quality of life. Increasing evidence indicates that diabetes is also one of the most prevalent disorders characterized by impaired skeletal muscle regeneration, yet underlying mechanisms and therapeutic treatments remain poorly established. In this review, we describe the cellular and molecular alterations currently known to occur during skeletal muscle regeneration in people with diabetes and animal models of diabetes, including its associated comorbidities, e.g., obesity, hyperinsulinemia, and insulin resistance. We describe the role of myogenic and non-myogenic cell types on muscle regeneration in conditions with or without diabetes. Therapies for skeletal muscle regeneration and gaps in our knowledge are also discussed, while proposing future directions for the field.

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.

Mapping the causal associations of cytokines with sarcopenia and aging traits: Evidence from bidirectional Mendelian randomization

BACKGROUND

Cytokines and growth factors may serve as a bridge in studying the causal relationships between inflammaging and sarcopenia due to their roles in inflammaging. In this study, we aim to explore the causal association of cytokines with sarcopenia and aging traits and further identify the significant inflammation factors.

METHODS

Bidirectional Mendelian randomization (MR) analysis was used to identify the causality. Forty-one kinds of circulation cytokines and growth factors were set as exposures, and the data were from a summary genome-wide association study (GWAS) containing three cohorts with 8293 healthy participants of European ancestry from 1983 to 2011. Hand grip strength, adjusted appendicular lean mass (AALM), usual walking pace, moderate-to-vigorous physical activity (MVPA) levels, able to walk or cycle unaided for 10 min (AWCU10) and telomere length were selected as outcomes. Data for outcomes were obtained from meta-GWAS and the UK Biobank, and sample sizes ranged from 69 537 to 472 174. Low hand grip strength was defined by the European Working Group on Sarcopenia in Older People (EWGSOP) and Foundation for the National Institutes of Health (FNIH) cut-off points, respectively. Other outcome traits were defined and measured according to the UK Biobank and raw cohorts' criteria. We set two significance thresholds for single nucleotide polymorphisms (SNPs) associated with exposures to obtain adequate SNPs (5 × 10-6 and 5 × 10-8). Inverse-variance weighted, MR-Egger and weighted median were employed to estimate the causality.

RESULTS

Twenty-seven factors were identified to relate to sarcopenia and aging traits causally, and most were associated with only one outcome trait. IL16 (interleukin-16), CTACK (cutaneous T-cell attracting chemokine), MIP1b (macrophage inflammatory protein 1b) and PDGFbb (platelet-derived growth factor BB) were proven to relate causally to at least one sarcopenia and aging trait in both analyses with two significance thresholds. IL16 was causally associated with hand grip strength (0.977 [0.956-0.998] for EWGSOP and 0.933 [0.874-0.996] for FNIH), AALM (0.991 [0.984, 0.998]), MVPA (0.997 [0.995-1.000]) and AWCU10 (1.008 [1.003-1.013]). CTACK was proven to relate causally to hand grip strength (1.013 [1.007-1.019] for EWGSOP and 1.090 [1.041-1.142] for FNIH), AWCU10 (0.990 [0.986-0.994]) and telomere length (0.998 [0.983-0.994]). The results indicated that MIP1b has a causal effect on hand grip strength (1.032 [1.001-1.063] for EWGSOP), AWCU10 (0.994 [0.988-1.000] and 0.993 [0.988-0.998]) and telomere length (1.006 [1.000-1.012]). PDGFbb may causally relate to AALM (1.016 [1.001-1.030]) and telomere length (1.011 [1.007-1.015]). Reserve MR analyses also proved their unidirectional causal effects.

CONCLUSIONS

Twenty-seven factors were causally related to sarcopenia and aging traits, and the causal effects of IL16, CTACK, MIP1b and PDGFbb were proven in both analyses with two significance thresholds.

Causal association of circulating cytokines with sarcopenia-related traits: A Mendelian randomization study

BACKGROUND

Observational studies have reported that circulating cytokines are associated with sarcopenia. However, the causal relationship between circulating cytokines and sarcopenia has not been elucidated.

OBJECTIVES

This study aimed to investigate the causal relationship between circulating cytokines and sarcopenia with genetic data using Mendelian randomization (MR).

METHODS

Two-sample bidirectional MR analysis was performed to investigate the causal relationship in individuals of European ancestry. The publicly available genome-wide association study statistics were used to select the key eligible single nucleotide polymorphisms significantly associated with circulating cytokines. Multiple MR analysis approaches, including inverse variance weighted (IVW), MR-Egger, weighted median method (WMM), and MR-Pleiotropy residual Sum and Outlier (MR-PRESSO) methods, were used for the analysis. Sarcopenia-related traits were appendicular lean mass (ALM) and grip strength.

RESULTS

This study demonstrated the causal effect of genetically predicted circulating interleukin interleukin-16 (IL16) levels on both ALM [odds ratio (OR) = 0.990, 95% confidence interval (CI): 0.980-1.000, P = 0.049] and grip strength (OR = 0.971, 95% CI: 0.948-0.995, P = 0.020]. Additionally, C-X-C motif chemokine ligand 10 (CXCL10), interleukin-1beta (IL1B), and hepatocyte growth factor (HGF) were correlated with ALM, while vascular endothelial growth factor (VEGF), interleukin-12 (IL12), and interleukin-15 (IL15) were correlated with grip strength. The results of MR-Egger, weighted median, weighted mode, and simple mode methods were consistent with the IVW estimates. Sensitivity analysis revealed that horizontal pleiotropy did not bias the causal estimates.

CONCLUSION

These findings indicate that inflammatory cytokines exert a significant causal effect on sarcopenia and provide promising leads for the development of novel therapeutic targets for the disease. By evaluating the role of circulating cytokines in the pathologic condition via a genetic epidemiological approach, our study made contributions to a further investigation of underlying mechanisms of sarcopenia.

Causal relationship between sarcopenia with osteoarthritis and the mediating role of obesity: a univariate, multivariate, two-step Mendelian randomization study

BACKGROUND

Recent genetic evidence supports a causal role for sarcopenia in osteoarthritis, which may be mediated by the occurrence of obesity or changes in circulating inflammatory protein levels. Here, we leveraged publicly available genome-wide association study data to investigate the intrinsic causal relationship between sarcopenia, obesity, circulating inflammatory protein levels, and osteoarthritis.

METHODS

In this study, we used Mendelian randomization analyses to explore the causal relationship between sarcopenia phenotypes (Appendicular lean mass [ALM], Low hand-grip strength [LHG], and usual walking pace [UWP]) and osteoarthritis (Knee osteoarthritis [KOA], and Hip osteoarthritis [HOA]). Univariable Mendelian randomization (UVMR) analyses were performed using the inverse variance weighted (IVW) method, MR-Egger, weighted median method, simple mode, and weighted mode, with the IVW method being the primary analytical technique. Subsequently, the independent causal effects of sarcopenia phenotype on osteoarthritis were investigated using multivariate Mendelian randomization (MVMR) analysis. To further explore the mechanisms involved, obesity and circulating inflammatory proteins were introduced as the mediator variables, and a two-step Mendelian randomization analysis was used to explore the mediating effects of obesity and circulating inflammatory proteins between ALM and KOA as well as the mediating proportions.

RESULTS

UVMR analysis showed a causal relationship between ALM, LHG, UWP and KOA [(OR = 1.151, 95% CI: 1.087-1.218, P = 1.19 × 10-6, PFDR = 7.14 × 10-6) (OR = 1.215, 95% CI: 1.004-1.470; P = 0.046, PFDR = 0.055) (OR = 0.503, 95% CI: 0.292-0.867; P = 0.013, PFDR = 0.027)], and a causal relationship between ALM, UWP and HOA [(OR = 1.181, 95% CI: 1.103-1.265, P = 2.05 × 10-6, PFDR = 6.15 × 10-6) (OR = 0.438, 95% CI: 0.226-0.849, P = 0.014, PFDR = 0.022)]. In the MVMR analyses adjusting for confounders (body mass index, insomnia, sedentary behavior, and bone density), causal relationships were observed between ALM, LHG, UWP and KOA [(ALM: OR = 1.323, 95%CI: 1.224- 1.431, P = 2.07 × 10-12), (LHG: OR = 1.161, 95%CI: 1.044- 1.292, P = 0.006), (UWP: OR = 0.511, 95%CI: 0.290- 0.899, P = 0.020)], and between ALM and HOA (ALM: OR = 1.245, 95%CI: 1.149- 1.348, P = 7.65 × 10-8). In a two-step MR analysis, obesity was identified to play a potential mediating role in ALM and KOA (proportion mediated: 5.9%).

CONCLUSIONS

The results of this study suggest that decreased appendicular lean mass, grip strength, and walking speed increase the risk of KOA and decreased appendicular lean mass increases the risk of HOA in patients with sarcopenia in a European population. Obesity plays a mediator role in the occurrence of KOA due to appendicular lean body mass reduction.

Causal association of sarcopenia with hepatocellular carcinoma risk in European population: a Mendelian randomization study

Background

The causal association of sarcopenia with the incidence risk of hepatocellular carcinoma (HCC) in the European population, and the potential mediating role of C-reactive protein (CRP), remains unclear. This study employed a bidirectional two-sample, two-step Mendelian randomization (MR) analysis to investigate the causality and identify the mediator.

Methods

Summary statistics for HCC, CRP, and sarcopenia-related traits, including appendicular lean mass (ALM), hand grip strength (HGS), and walking pace (WP), were acquired from publicly available databases. We conducted bidirectional MR and Steiger tests of directionality to check the presence of reverse causality. Additionally, a two-step MR analysis was used to assess the mediating effect of CRP in the causality between sarcopenia and HCC. Tests for heterogeneity and horizontal pleiotropy were performed.

Results

As ALM increases, the risk of HCC occurrence decreases [odds ratio (OR), 95% confidence interval (CI): 0.703, 0.524-0.943; P = 0.019]. And, genetically predicted low-HGS (OR, 95%CI: 2.287, 1.013-5.164; P = 0.047) was associated with an increased incidence risk of HCC, with no reverse causality. However, we found no evidence supporting a causality between WP and HCC. CRP was identified as the mediator of the causal effect of ALM and low-HGS on HCC, with corresponding mediating effects of 9.1% and 7.4%.

Conclusions

This MR study effectively demonstrates that lower ALM and low-HGS are linked to an elevated risk of HCC within the European population, and the causality was not bidirectional. Furthermore, CRP serves as a mediator in the associations. These findings may help mitigate HCC risk among individuals with sarcopenia.

A genome-wide association study identifies a locus associated with knee extension strength in older Japanese individuals

Sarcopenia is a common skeletal muscle disease in older people. Lower limb muscle strength is a good predictive value for sarcopenia; however, little is known about its genetic components. Here, we conducted a genome-wide association study (GWAS) for knee extension strength in a total of 3452 Japanese aged 60 years or older from two independent cohorts. We identified a significant locus, rs10749438 which is an intronic variant in TACC2 (transforming acidic coiled-coil-containing 2) (P = 4.2 × 10-8). TACC2, encoding a cytoskeleton-related protein, is highly expressed in skeletal muscle, and is reported as a target of myotonic dystrophy 1-associated splicing alterations. These suggest that changes in TACC2 expression are associated with variations in muscle strength in older people. The association was consistently observed in young and middle-aged subjects. Our findings would shed light on genetic components of lower limb muscle strength and indicate TACC2 as a potential therapeutic target for sarcopenia.

An insight into the causal relationship between sarcopenia-related traits and venous thromboembolism: A mendelian randomization study

BACKGROUND

As a geriatric syndrome, sarcopenia has a high prevalence in the old population and represents an impaired state of health with adverse health outcomes. A strong clinical interest in its relationship with venous thromboembolism (VTE), which is a complex trait disease with a heterogeneous annual incidence rate in different countries, has emerged. The relationship between sarcopenia and venous thromboembolism has been reported in observational studies but the causality from sarcopenia to VTE remained unclarified. We aimed to assess the causal effect of sarcopenia on the risk of VTE with the two-sample Mendelian randomization (MR) method.

METHODS

Two sets of single-nucleotide polymorphisms (SNPs), derived from two published genome-wide association study (GWAS) meta-analyses and genetically indexing muscle weakness and lean muscle mass separately, were pooled into inverse variance weighted (IVW), weighted median and MR-Egger analyses.

RESULTS

No evidence was found for the causal effect of genetically predicted muscle weakness (IVW: OR = 0.90, 95% CI = 0.76-1.06, p = 0.217), whole body lean mass (IVW: OR = 1.01, 95% CI = 0.87-1.17, p = 0.881) and appendicular lean mass (IVW: OR = 1.13, 95% CI = 0.82-1.57, p = 0.445) on the risk of VTE. However, both genetically predicted whole-body lean mass and appendicular lean mass can causally influence diabetes mellitus (IVW of whole-body lean mass: OR = 0.87, 95% CI = 0.78-0.96, p = 0.008; IVW of appendicular lean mass: OR = 0.71, 95% CI = 0.54-0.94, p = 0.014) and hypertension (IVW of whole-body lean mass: OR = 0.92, 95% CI = 0.87-0.98, p = 0.007; IVW of appendicular lean mass: OR = 0.84, 95% CI = 0.73-0.96, p = 0.013).

CONCLUSIONS

Genetically predicted sarcopenia does not causally influence VTE directly, but it might still have an indirect effect on VTE incidence via diabetes mellitus and hypertension.

Multimodal cell atlas of the ageing human skeletal muscle

Muscle atrophy and functional decline (sarcopenia) are common manifestations of frailty and are critical contributors to morbidity and mortality in older people1. Deciphering the molecular mechanisms underlying sarcopenia has major implications for understanding human ageing2. Yet, progress has been slow, partly due to the difficulties of characterizing skeletal muscle niche heterogeneity (whereby myofibres are the most abundant) and obtaining well-characterized human samples3,4. Here we generate a single-cell/single-nucleus transcriptomic and chromatin accessibility map of human limb skeletal muscles encompassing over 387,000 cells/nuclei from individuals aged 15 to 99 years with distinct fitness and frailty levels. We describe how cell populations change during ageing, including the emergence of new populations in older people, and the cell-specific and multicellular network features (at the transcriptomic and epigenetic levels) associated with these changes. On the basis of cross-comparison with genetic data, we also identify key elements of chromatin architecture that mark susceptibility to sarcopenia. Our study provides a basis for identifying targets in the skeletal muscle that are amenable to medical, pharmacological and lifestyle interventions in late life.

Association of High-Density Lipoprotein Cholesterol with Sarcopenia in Chinese Community-Dwelling Middle-Aged and Older Adults: Evidence from 4-Year Longitudinal Study

INTRODUCTION

There is inconsistent evidence on the associations between high-density lipoprotein cholesterol (HDL-C) and risk of sarcopenia. The aim of the study was to determine the evidence existing between HDL-C and sarcopenia in Chinese middle-aged and older adults.

METHODS

We used a panel study design of the China Health and Retirement Longitudinal Study (CHARLS), with 7,415 participants (mean age 57.5 years) from 2011, 2013, and 2015. HDL-C was measured by colorimetric test of venous serum samples. Sarcopenia was defined as low muscle mass, plus low muscle strength, or low physical performance. Muscle mass was estimated by anthropometric measures. Muscle strength was measured by handgrip strength using dynamometer. Physical performance was measured by 5-time chair stand test, gait speed test, and short physical performance battery.

RESULTS

With 961 (13.0%) sarcopenia cases, each 1-unit increase (1 SD = 15.4 mg/dL) of HDL-C levels was associated with 42% increased odds of incident sarcopenia (OR = 1.42, 95% confidence interval [CI] = 1.28-1.58) at 4-year follow-up. Females with high HDL-C levels (HDL-C >60 mg/dL) had a higher risk of sarcopenia (OR = 2.49, 95% CI = 1.76-3.52). The restricted cubic spline curves showed a J-shaped association between HDL-C and risk of sarcopenia in females. HDL-C was negatively associated with muscle mass (β = -0.23, 95% CI = -0.27 to -0.20) and hand grip strength (β = -0.05, 95% CI = -0.19 to 0.09).

CONCLUSION

High HDL-C levels were associated with higher risk of sarcopenia among middle-aged and older Chinese adults, and appropriate control of its high levels informs the management of sarcopenia.

Systematic druggable genome-wide Mendelian randomization identifies therapeutic targets for sarcopenia

BACKGROUND

There are no effective pharmacological treatments for sarcopenia. We aim to identify potential therapeutic targets for sarcopenia by integrating various publicly available datasets.

METHODS

We integrated druggable genome data, cis-eQTL/cis-pQTL from human blood and skeletal muscle tissue, and GWAS summary data of sarcopenia-related traits to analyse the potential causal relationships between drug target genes and sarcopenia using the Mendelian Randomization (MR) method. Sensitivity analyses and Bayesian colocalization were employed to validate the causal relationships. We also assessed the side effects or additional indications of the identified drug targets using a phenome-wide MR (Phe-MR) approach and investigated actionable drugs for target genes using available databases.

RESULTS

MR analysis identified 17 druggable genes with potential causation to sarcopenia in human blood or skeletal muscle tissue. Six of them (HP, HLA-DRA, MAP 3K3, MFGE8, COL15A1, and AURKA) were further confirmed by Bayesian colocalization (PPH4 > 90%). The up-regulation of HP [higher ALM (beta: 0.012, 95% CI: 0.007-0.018, P = 1.2*10-5) and higher grip strength (OR: 0.96, 95% CI: 0.94-0.98, P = 4.2*10-5)], MAP 3K3 [higher ALM (beta: 0.24, 95% CI: 0.21-0.26, P = 1.8*10-94), higher grip strength (OR: 0.82, 95% CI: 0.75-0.90, P = 2.1*10-5), and faster walking pace (beta: 0.03, 95% CI: 0.02-0.05, P = 8.5*10-6)], and MFGE8 [higher ALM (muscle eQTL, beta: 0.09, 95% CI: 0.06-0.11, P = 6.1*10-13; blood pQTL, beta: 0.05, 95% CI: 0.03-0.07, P = 3.8*10-09)], as well as the down-regulation of HLA-DRA [lower ALM (beta: -0.09, 95% CI: -0.11 to -0.08, P = 5.4*10-36) and lower grip strength (OR: 1.13, 95% CI: 1.07-1.20, P = 1.8*10-5)] and COL15A1 [higher ALM (muscle eQTL, beta: -0.07, 95% CI: -0.10 to -0.04, P = 3.4*10-07; blood pQTL, beta: -0.05, 95% CI: -0.06 to -0.03, P = 1.6*10-07)], decreased the risk of sarcopenia. AURKA in blood (beta: -0.16, 95% CI: -0.22 to -0.09, P = 2.1*10-06) and skeletal muscle (beta: 0.03, 95% CI: 0.02 to 0.05, P = 5.3*10-05) tissues showed an inverse relationship with sarcopenia risk. The Phe-MR indicated that the six potential therapeutic targets for sarcopenia had no significant adverse effects. Drug repurposing analysis supported zinc supplementation and collagenase clostridium histolyticum might be potential therapeutics for sarcopenia by activating HP and inhibiting COL15A1, respectively.

CONCLUSIONS

Our research indicated MAP 3K3, MFGE8, COL15A1, HP, and HLA-DRA may serve as promising targets for sarcopenia, while the effectiveness of zinc supplementation and collagenase clostridium histolyticum for sarcopenia requires further validation.

Creatine Supplementation and Resistance Training in Patients With Breast Cancer (CaRTiC Study): Protocol for a Randomized Controlled Trial

BACKGROUND

Creatine supplementation is an effective ergogenic nutrient for athletes, as well as for people starting a health or fitness program. Resistance training has previously been identified as an important method of increasing muscle mass and strength, especially in people with cancer to avoid sarcopenia. The potential of creatine supplementation for adaptations produced by resistance training in patients with cancer is still unknown. The primary aim of this study is to evaluate the effectiveness of a supervised resistance training program intervention with and without creatine supplementation in patients with breast cancer.

METHODS

Is a multicentre, randomized, blind, placebo-controlled study. Patients will be randomly assigned to a control group and 2 experimental groups. The first training resistance group (RG) will perform resistance training, while the second experimental resistance-creatine group will perform the same resistance training as the RG and will also receive a 5 g/d creatine supplementation during the intervention. RG participants will follow the same daily dosing protocol, but in their case, with dextrose/maltodextrin. Resistance training will be a 16-week supervised workout that will consist of a series of resistance exercises (leg press, knee extension, knee bends, chest press, sit-ups, back extensions, pull-ups, and shoulder press) that involve the largest muscle groups, performed 3 times a week on nonconsecutive days. Both the RG and the resistance-creatine group will receive a supplement of soluble protein powder (20 to 30 g) daily.

CONCLUSION

This intervention will help to better understand the potential of nonpharmacological treatment for improving strength and well-being values in patients with breast cancer with and without creatine supplementation.

The bidirectional associations between sarcopenia-related traits and cognitive performance

While many studies have sought to explore the degree to which sarcopenia-related traits are associated with cognitive performance, these studies have yielded contradictory results without any clear indication of the causality of such relationships. In efforts to better understand associations between sarcopenia-related traits and cognitive ability, a series of multivariate linear regression assessments were carried out upon datasets derived through the National Health and Nutrition Examination Survey (NHANES). Of these, cognitive performance was assessed by the Digit Symbol Substitution Test (DDST), the Consortium to Establish a Registry for Alzheimer's Disease Immediate Recall Test (CERAD-IR), Delayed Recall Test (CERAD-DR) and Animal Fluency Test (AFT). Causal relationships between the two were further inferred via a two-sample Mendelian randomization (MR) analysis approach. Sarcopenia-related traits considered in these assessments included walking speed, appendicular skeletal muscle mass (ASM), and hand grip strength (HGS). Walking speed, ASM, and HGS were all significantly independently related to cognitive scores following adjustment for covariates. MR assessments also identified that each 1-SD higher walking speed and appendicular lean mass were causally and respectively associated with a 0.34 [standard error (SE) = 0.09; p < 0.001)] standardized score higher and a 0.07 (SE = 0.01; p < 0.001) standardized score higher cognitive score, whereas a higher hand grip strength was positively associated with a better cognitive performance. Reverse MR assessments also yielded similar findings. These data suggest that lower walking speed, muscle strength, and muscle mass were all closely related to lower cognitive performance irrespective of gender, and that there may be a mutually reinforcing relationship among these variables.

The causal association between circulating cytokines with the risk of frailty and sarcopenia under the perspective of geroscience

Introduction

Circulating cytokines were considered to play a critical role in the initiation and propagation of sarcopenia and frailty from observational studies. This study aimed to find the casual association between circulating cytokines and sarcopenia and frailty from a genetic perspective by two-sample Mendelian randomization (MR) analysis.

Methods

Data for 41 circulating cytokines were extracted from the genome-wide association study dataset of 8,293 European participants. Inverse-variance weighted (IVW) method, MR-Egger, and weighted median method were applied to assess the relationship of circulating cytokines with the risk of aging-related syndromes and frailty. Furthermore, MR-Egger regression was used to indicate the directional pleiotropy, and Cochran's Q test was used to verify the potential heterogeneity. The "leave-one-out" method was applied to visualize whether there was a causal relationship affected by only one anomalous single-nucleotide polymorphisms.

Results

Genetic predisposition to increasing levels of interleukin-10 (IL-10), IL-12, and vascular endothelial growth factor (VEGF) was associated with the higher risk of low hand grip strength according to the IVW method [R = 1.05, 95% CI = 1.01-1.10, P = 0.028, false discovery rate (FDR)-adjusted P = 1.000; OR = 1.03, 95% CI = 1.00-1.07, P = 0.042, FDR-adjusted P = 0.784; OR = 1.02, 95% CI = 1.00-1.05, P = 0.038, FDR-adjusted P = 0.567]. Furthermore, genetically determined higher macrophage colony-stimulating factors (M-CSFs) were associated with a lower presence of appendicular lean mass (OR = 1.01, 95% CI = 1.00-1.02, P = 0.003, FDR-adjusted P = 0.103). Monokine induced by interferon-γ (MIG) and tumor necrosis factor-beta (TNF-β) were associated with a higher risk of frailty (OR = 1.03, 95% CI = 1.01-1.05, P < 0.0001, FDR-adjusted P = 0.012; OR = 1.01, 95% CI = 1.00-1.03, P = 0.013, FDR-adjusted P = 0.259). In this study, we did not find heterogeneity and horizontal pleiotropy between the circulating cytokines and the risk of frailty and sarcopenia.

Conclusion

Genetic predisposition to assess IL-10, IL-12, and VEGF levels was associated with a higher risk of low hand grip strength and M-CSF with the presence of appendicular lean mass. The high levels of TNF-β and MIG were associated with a higher risk of frailty. More studies will be required to explore the molecular biological mechanisms underlying the action of inflammatory factors.

Metabolic clues to aging: exploring the role of circulating metabolites in frailty, sarcopenia and vascular aging related traits and diseases

Background: Physical weakness and cardiovascular risk increase significantly with age, but the underlying biological mechanisms remain largely unknown. This study aims to reveal the causal effect of circulating metabolites on frailty, sarcopenia and vascular aging related traits and diseases through a two-sample Mendelian Randomization (MR) analysis. Methods: Exposures were 486 metabolites analyzed in a genome-wide association study (GWAS), while outcomes included frailty, sarcopenia, arterial stiffness, atherosclerosis, peripheral vascular disease (PAD) and aortic aneurysm. Primary causal estimates were calculated using the inverse-variance weighted (IVW) method. Methods including MR Egger, weighted median, Q-test, and leave-one-out analysis were used for the sensitive analysis. Results: A total of 125 suggestive causative associations between metabolites and outcomes were identified. Seven strong causal links were ultimately identified between six metabolites (kynurenine, pentadecanoate (15:0), 1-arachidonoylglycerophosphocholine, androsterone sulfate, glycine and mannose) and three diseases (sarcopenia, PAD and atherosclerosis). Besides, metabolic pathway analysis identified 13 significant metabolic pathways in 6 age-related diseases. Furthermore, the metabolite-gene interaction networks were constructed. Conclusion: Our research suggested new evidence of the relationship between identified metabolites and 6 age-related diseases, which may hold promise as valuable biomarkers.

Genetic evidence of the causal relationship between chronic liver diseases and musculoskeletal disorders

BACKGROUND

Chronic liver diseases constitute a major global public health burden, posing a substantial threat to patients' daily lives and even survival due to the potential development of musculoskeletal disorders. Although the relationship between chronic liver diseases and musculoskeletal disorders has received extensive attention, their causal relationship has not been comprehensively and systematically investigated.

METHODS

This study aimed to assess the causal relationships between viral hepatitis, primary biliary cholangitis, primary sclerosing cholangitis (PSC), liver cirrhosis, and hepatocellular carcinoma (HCC) with osteoporosis, osteoarthritis, and sarcopenia through bidirectional Mendelian randomization (MR) research. The traits related to osteoporosis and osteoarthritis included both overall and site-specific phenotypes, and the traits linked to sarcopenia involved indicators of muscle mass and function. Random-effect inverse-variance weighted (IVW), weighted median, MR-Egger, and Causal Analysis Using the Summary Effect Estimates were used to evaluate causal effects, with IVW being the main analysis method. To enhance robustness, sensitivity analyses were performed using Cochran's Q test, MR-Egger intercept, MR-PRESSO global test, funnel plots, leave-one-out analyses, and latent causal variable model.

RESULTS

The forward MR analysis indicated that PSC can reduce forearm bone mineral density (beta = - 0.0454, 95% CI - 0.0798 to - 0.0110; P = 0.0098) and increase the risk of overall osteoarthritis (OR = 1.012, 95% CI 1.002-1.022; P = 0.0247), while HCC can decrease grip strength (beta = - 0.0053, 95% CI - 0.008 to - 0.0025; P = 0.0002). The reverse MR analysis did not find significant causal effects of musculoskeletal disorders on chronic liver diseases. Additionally, no heterogeneity or pleiotropy was detected.

CONCLUSIONS

These findings corroborate the causal effects of PSC on osteoporosis and osteoarthritis, as well as the causal impact of HCC on sarcopenia. Thus, the implementation of comprehensive preventive measures is imperative for PSC and HCC patients to mitigate the risk of musculoskeletal disorders, ultimately improving their quality of life.

Bibliometric and scientometric analysis on biomarkers and molecular mechanisms for physical frailty and sarcopenia

Introduction

The influence of physical frailty and sarcopenia (PFS) on the well-being of older people and continuous pressure on the healthcare systems has prompted a research on the pathophysiology and molecular mechanisms of these conditions. Nonetheless some biomarkers have been suggested as potential markers for PFS none of them have been shown to highlight the complex nature of PFS, which reveals that there is a need for an understanding of the possible biomarker candidates. The aim of this study was to identify the current research hotspots, status, and trends in the field of biomarkers and molecular mechanisms for PFS.

Methods

The bibliometric and scientometric analyses were performed using VOSviewer (version 1.6.18) and open source software platform Cytoscape v.3.9 (for visualizing and constructing a network of keywords). Data of publications (from 1997 to 2023) related to biomarkers and molecular mechanisms of PFS were obtained (in May 2023) from the database of Science Citation Index Expanded of Web of Science, Scopus, and PubMed. The keywords obtained from the Scopus database were used to perform a meaningful keyword analysis. A network of keyword relationships was build using Cytoscape.

Results

In this study, we present biomarker keywords for PFS in relation to other keywords potentially designating processes and mechanisms and reveal the biomarker identities and current contexts in which these biomarker identities are discussed.

Conclusions

Over recent years, scientific interest in the field of PFS has increased and focused on the inflammatory process and probably will be concentrated on myokines (such as cytokines and small proteins) that are synthetized and released by skeletal muscles in response to physical activity. Moreover, proteomic and genetic markers are deeply involved in PFS.

Immunogenetic Aspects of Sarcopenic Obesity

Sarcopenic obesity (SO) is a combination of obesity and sarcopenia, with diagnostic criteria defined as impaired skeletal muscle function and altered body composition (e.g., increased fat mass and reduced muscle mass). The mechanism of SO is not yet perfectly understood; however, the pathogenesis includes aging and its complications, chronic inflammation, insulin resistance (IR), and hormonal changes. Genetic background is apparent in the pathogenesis of isolated obesity, which is most often polygenic and is characterized by the additive effect of various genetic factors. The genetic etiology has not been strictly established in SO. Still, many data confirm the existence of pathogenic gene variants, e.g., Fat Mass and Obesity Associated Gene (FTO), beta-2-adrenergic receptor (ADRB2) gene, melanocortin-4 receptor (MC4R) and others with obesity. The literature on the role of these genes is scarce, and their role has not yet been thoroughly established. On the other hand, the involvement of systemic inflammation due to increased adipose tissue in SO plays a significant role in its pathophysiology through the synthesis of various cytokines such as monocyte chemoattractant protein-1 (MCP-1), IL-1Ra, IL-15, adiponectin or CRP. The lack of anti-inflammatory cytokine (e.g., IL-15) can increase SO risk, but further studies are needed to evaluate the exact mechanisms of implications of various cytokines in SO individuals. This manuscript analyses various immunogenetic and non-genetic factors and summarizes the recent findings on immunogenetics potentially impacting SO development.

Precision MRI phenotyping of muscle volume and quality at a population scale

Introduction: Magnetic resonance imaging (MRI) enables direct measurements of muscle volume and quality, allowing for an in-depth understanding of their associations with anthropometric traits, and health conditions. However, it is unclear which muscle volume measurements: total muscle volume, regional measurements, measurements of muscle quality: intermuscular adipose tissue (IMAT) or proton density fat fraction (PDFF), are most informative and associate with relevant health conditions such as dynapenia and frailty. Methods: We have measured image-derived phenotypes (IDPs) including total and regional muscle volumes and measures of muscle quality, derived from the neck-to-knee Dixon images in 44,520 UK Biobank participants. We further segmented paraspinal muscle from 2D quantitative MRI to quantify muscle PDFF and iron concentration. We defined dynapenia based on grip strength below sex-specific cut-off points and frailty based on five criteria (weight loss, exhaustion, grip strength, low physical activity and slow walking pace). We used logistic regression to investigate the association between muscle volume and quality measurements and dynapenia and frailty. Results: Muscle volumes were significantly higher in male compared with female participants, even after correcting for height while, IMAT (corrected for muscle volume) and paraspinal muscle PDFF were significantly higher in female compared with male participants. From the overall cohort, 7.6% (N = 3,261) were identified with dynapenia, and 1.1% (N = 455) with frailty. Dynapenia and frailty were positively associated with age and negatively associated with physical activity levels. Additionally, reduced muscle volume and quality measurements were associated with both dynapenia and frailty. In dynapenia, muscle volume IDPs were most informative, particularly total muscle exhibiting odds ratios (OR) of 0.392, while for frailty, muscle quality was found to be most informative, in particular thigh IMAT volume indexed to height squared (OR = 1.396), both with p-values below the Bonferroni-corrected threshold (p < 8.8 × 10 - 5 ). Conclusion: Our fully automated method enables the quantification of muscle volumes and quality suitable for large population-based studies. For dynapenia, muscle volumes particularly those including greater body coverage such as total muscle are the most informative, whilst, for frailty, markers of muscle quality were the most informative IDPs. These results suggest that different measurements may have varying diagnostic values for different health conditions.

Allergic Phenotypes and Sarcopenia: Evidence from Observational Studies and Mendelian Randomization Analysis

Commonly affected in early-life population, the impact of allergic phenotypes on mid- or late-life health is less discussed. This study is to explore the association of allergic phenotypes including atopic dermatitis (AD), asthma, eosinophils count (EC), and sarcopenia. We conducted observational studies and mendelian randomization (MR) analysis based on UK Biobank (UKB), the China Health and Retirement Longitudinal Study (CHARLS) and data from genome-wide association study (GWAS). Based on the UKB data, AD, asthma and EC were positively correlated with pre-sarcopenia and decreased skeletal muscle mass index and hand grip in fully adjusted model. Asthma and EC were significantly associated with sarcopenia while AD was marginally associated (p = 0.095). Based on the CHARLS cohort, asthma significantly added 109.4% risk for pre-sarcopenia in adjusted model (relative risk = 2.094; p = 0.002), respectively. Both asthma (β = 0.100, p = 0.006) and EC (β = 0.023, p = 0.017) exerted significantly casual effects on pre-sarcopenia. However, as for sarcopenia, merely EC exhibited a significantly casual effect (β = 0.005, p = 0.048). Significant casual effects of AD (β = - 0.027, p = 0.003), asthma (β = - 0.029, p = 0.027) and EC (β = - 0.041, p < 0.001) on decreased appendicular lean mass (ALM) were observed using the inverse-variance weighted method and the Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) method. Our results revealed a contributory role of AD, asthma and EC on sarcopenia, especially in terms of decreased ALM, an indicator for sarcopenia diagnosis. The findings of our study will raise the awareness of preventing aging-related disorders or geriatric syndromes among allergic populations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-023-00110-4.

Diagnostic Criteria and Measurement Techniques of Sarcopenia: A Critical Evaluation of the Up-to-Date Evidence

Sarcopenia, a geriatric syndrome characterized by progressive skeletal muscle mass and function decline, poses a significant health risk among the elderly, contributing to frailty, falls, hospitalization, loss of independence and mortality. The prevalence of sarcopenia varies significantly based on various factors, such as living status, demographics, measurement techniques and diagnostic criteria. Although the overall prevalence is reported at 10% in individuals aged 60 and above, disparities exist across settings, with higher rates in nursing homes and hospitals. Additionally, the differences in prevalence between Asian and non-Asian countries highlight the impact of cultural and ethnic factors, and variations in diagnostic criteria, cut-off values and assessment methods contribute to the observed heterogeneity in reported rates. This review outlines diverse diagnostic criteria and several measurement techniques supporting decision making in clinical practice. Moreover, it facilitates the selection of appropriate tools to assess sarcopenia, emphasizing its multifactorial nature. Various scientific groups, including the European Working Group of Sarcopenia in Older People (EWGSOP), the International Working Group on Sarcopenia (IWGS), the Asian Working Group on Sarcopenia (AWGS), the American Foundation for the National Institutes of Health (FNIH) and the Sarcopenia Definition and Outcomes Consortium (SDOC), have published consensus papers outlining diverse definitions of sarcopenia. The choice of diagnostic criteria should be aligned with the specific objectives of the study or clinical practice, considering the characteristics of the study population and available resources.

Multi-trait analysis characterizes the genetics of thyroid function and identifies causal associations with clinical implications

To date only a fraction of the genetic footprint of thyroid function has been clarified. We report a genome-wide association study meta-analysis of thyroid function in up to 271,040 individuals of European ancestry, including reference range thyrotropin (TSH), free thyroxine (FT4), free and total triiodothyronine (T3), proxies for metabolism (T3/FT4 ratio) as well as dichotomized high and low TSH levels. We revealed 259 independent significant associations for TSH (61% novel), 85 for FT4 (67% novel), and 62 novel signals for the T3 related traits. The loci explained 14.1%, 6.0%, 9.5% and 1.1% of the total variation in TSH, FT4, total T3 and free T3 concentrations, respectively. Genetic correlations indicate that TSH associated loci reflect the thyroid function determined by free T3, whereas the FT4 associations represent the thyroid hormone metabolism. Polygenic risk score and Mendelian randomization analyses showed the effects of genetically determined variation in thyroid function on various clinical outcomes, including cardiovascular risk factors and diseases, autoimmune diseases, and cancer. In conclusion, our results improve the understanding of thyroid hormone physiology and highlight the pleiotropic effects of thyroid function on various diseases.

Assessing causality between inflammatory bowel diseases with frailty index and sarcopenia: a bidirectional Mendelian randomization study

BACKGROUND

Previous studies have found that frailty and sarcopenia are commonly diagnosed in inflammatory bowel disease (IBD) patients, indicating an association between these conditions. Nonetheless, the cause‒effect connection between IBD, frailty, and sarcopenia remains unclear.

METHODS

We sourced the genetic variants for the exposures and outcomes from publicly accessible, extensive genome-wide association studies (GWAS). Specifically, we obtained IBD data from the International IBD Genetics Consortium, frailty index (FI) data from the United Kingdom Biobank and Swedish TwinGene, and sarcopenia data from a recent GWAS meta-analysis. Five methods, including inverse variance weighted (IVW), simple mode, MR-Egger, weighted mode, and the weighted median, were used to proceed with MR estimates. We also performed heterogeneity and horizontal pleiotropy tests.

RESULTS

Our results indicated a positive causal relationship between ulcerative colitis (UC) (IVW: β = 0.014, 95% CI, 0.006 to 0.021, p = 0.001) and Crohn's disease (CD) (IVW: β = 0.012; 95% CI, 0.006 to 0.018, p = 2e-04) with the FI. However, we uncovered no proof of a cause-and-effect relationship between UC (IVW: β = 0.001, 95% CI, -0.015 to 0.017, p = 0.344) or CD (IVW: β = 0.003, 95% CI, -0.009 to 0.015, p = 0.214) and sarcopenia. Additionally, in the inverse order, we also discovered no cause-and-effect connection between FI or sarcopenia on UC or CD in this study.

CONCLUSION

The MR analysis showed a positive causal association between IBD and FI, indicating that IBD patients may exhibit aging-related characteristics. Therefore, frailty assessments should be conducted as early as possible in IBD patients.

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.

Causal Roles of Lifestyle, Psychosocial Characteristics, and Sleep Status in Sarcopenia: A Mendelian Randomization Study

BACKGROUND

Many studies reported that lifestyle, psychosocial characteristics, and sleep status related to sarcopenia, although few studies provided evidence of causal relationships between them.

METHODS

The data used in our study were from UK Biobank, FinnGen Release 8, and large genome-wide association study meta-analyses. Two-sample Mendelian randomization was conducted to identify the causal associations of 21 traits of lifestyle, psychosocial characteristics, and sleep status with 6 traits of sarcopenia. Benjamini-Hochberg correction was performed to reduce the bias caused by multiple tests. Risk factor analyses were performed to explore the potential mechanism behind the exposures.

RESULTS

Mendelian randomization analyses after adjustment proved the causal roles of coffee intake, education years, smoking, leisure screen time, and moderate-to-vigorous intensity physical activity during leisure time in sarcopenia was proven although providing no significant evidence for causal roles for carbohydrates intake, protein intake, alcohol, and sleep status in sarcopenia.

CONCLUSIONS

Our results strongly support that coffee intake, education years, smoking, leisure screen time, and moderate-to-vigorous intensity physical activity during leisure time played significantly causal roles in sarcopenia, which may provide new intervention strategies for preventing the development of sarcopenia.

The relationship between lifestyles and sarcopenia-related traits: A two-sample Mendelian randomization study

OBJECTIVE

To investigate the causal association between lifestyles (smoking, drinking consumption and physical activity) and sarcopenia-related traits by Mendelian randomized analysis.

METHODS

Instrumental variables from the genome-wide association study were used for analysis. The exposure factors were lifestyle factors, including smoking, alcohol consumption, moderate physical activity and vigorous physical activity, and the outcome variables were low hand grip strength and appendicular lean mass. The inverse variance weighted (IVW) method and other MR methods were used for analysis. Heterogeneity test, sensitivity analysis and pleiotropy analysis were performed.

RESULTS

According to a primary causal effects model with MR analyses by the IVW method, smoking was a decreased risk of low hand grip strength (odds ratio (OR) = 0.899, 95% confidence interval (CI) = 0.829-0.974, P = 0.010), while alcohol consumption was a significant correlation with low hand grip strength (OR = 1.137, 95% CI = 1.020-1.267, P = 0.020). There was no significant relationship between smoking, alcohol, and appendicular lean mass. In addition, moderate or vigorous physical showed no significant correlation with low hand grip strength and appendicular lean mass.

CONCLUSION

This study demonstrated that smoking may be causally related to a lower risk of low hand grip strength, while alcohol may increase the risk of low hand grip strength. There was no causal relationship between physical activity and sarcopenia-related traits.

Genetically Proxied Sarcopenia-Related Muscle Traits and Depression: Evidence from the FinnGen Cohort

BACKGROUND

Sarcopenia and depression are common and often coexist in the elderly. This study aims to determine the impact of sarcopenia-related muscle traits on depression.

METHODS

A two-sample Mendelian randomization (MR) study was performed on the summary-level data from the FinnGen cohort to estimate the causal association of appendicular lean mass (ALM), walking pace, or low hand grip strength with depression. Additionally, multivariable MR (MVMR) was performed to assess the dependence of each muscle trait in the causality and adjust the effect of body mass index (BMI). Supplementary backward MR analyses were performed to estimate the effect of depression on sarcopenia-related muscle traits.

RESULTS

Univariable MR analyses demonstrated that there were causal associations of ALM (odds ratio [OR]: 0.94; 95% confidence interval [CI]: 0.88-0.99), walking pace (OR: 0.53; 95% CI: 0.32-0.88), and low hand grip strength (OR: 1.20; 95% CI: 1.05-1.38) with depression. MVMR analyses showed that ALM was the only trait that had a significant causal relationship with depression (OR: 0.91; 95% CI: 0.85-0.98) after accounting for the other two muscle traits. Moreover, the independent association of ALM with depression remained (OR: 0.92; 95% CI: 0.85-0.99) after being adjusted by BMI. The backward MR analyses showed no causal associations of depression with any sarcopenia-related muscle traits.

CONCLUSION

Low muscle mass independently increases the risk of depression. This study determined the muscle-related risk factors of depression, which may help establish the causality between sarcopenia and depression and provide evidence-based recommendations for improving mental health in the elderly.

Causal relationship between lipid profile and muscle atrophy: A bi-directional Mendelian randomization study

BACKGROUND

The aim of this study was to analyze the bi-directional causal relationship between lipid profile and characteristics related to muscle atrophy by using a bi-directional Mendelian randomization (MR) analysis.

METHODS

The appendicular lean mass (ALM), whole body fat-free mass (WBFFM) and trunk fat-free mass (TFFM) were used as genome-wide association study (GWAS) data for evaluating muscle mass; the usual walking pace (UWP) and low grip strength (LGS) were used as GWAS data for evaluating muscle strength; and the triglycerides (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL), apolipoprotein A-1 (Apo A-1), and apolipoprotein B (Apo B) were used as GWAS data for evaluating lipid profile. For specific investigations, we mainly employed inverse variance weighting for causal estimation and MR-Egger for pleiotropy analysis.

RESULTS

MR results showed that the lipid profile predicted by genetic variants was negatively correlated with muscle mass, positively correlated with UWP, and was not causally correlated with LGS. On the other hand, the muscle mass predicted by genetic variants was negatively correlated with lipid profile, the UWP predicted by genetic variants was mainly positively correlated with lipid profile, while the LGS predicted by genetic variants had no relevant causal relationship with lipid profile.

CONCLUSIONS

Findings of this MR analysis suggest that hyperlipidemia may affect muscle mass and lead to muscle atrophy, but has no significant effect on muscle strength. On the other hand, increased muscle mass may reduce the incidence of dyslipidemia.

Causal influence of muscle weakness on cardiometabolic diseases and osteoporosis

The causal roles of muscle weakness in cardiometabolic diseases and osteoporosis remain elusive. This two-sample Mendelian randomization (MR) study aims to explore the causal roles of muscle weakness in the risk of cardiometabolic diseases and osteoporosis. 15 single nucleotide polymorphisms (SNPs, P < 5 × 10-8) associated with muscle weakness were used as instrumental variables. Genetic predisposition to muscle weakness led to increased risk of coronary artery disease (inverse variance weighted [IVW] analysis, beta-estimate: 0.095, 95% confidence interval [CI]: 0.023 to 0.166, standard error [SE]:0.036, P-value = 0.009) and reduced risk of heart failure (weight median analysis, beta-estimate: - 0.137, 95% CI - 0.264 to - 0.009, SE:0.065, P-value = 0.036). In addition, muscle weakness may reduce the estimated bone mineral density (eBMD, weight median analysis, beta-estimate: - 0.059, 95% CI - 0.110 to - 0.008, SE:0.026, P-value = 0.023). We found no MR associations between muscle weakness and atrial fibrillation, type 2 diabetes or fracture. This study provides robust evidence that muscle weakness is causally associated with the incidence of coronary artery disease and heart failure, which may provide new insight to prevent and treat these two cardiometabolic diseases.

The genetics of falling susceptibility and identification of causal risk factors

Falls represent a huge health and economic burden. Whilst many factors are associated with fall risk (e.g. obesity and physical inactivity) there is limited evidence for the causal role of these risk factors. Here, we used hospital and general practitioner records in UK Biobank, deriving a balance specific fall phenotype in 20,789 cases and 180,658 controls, performed a Genome Wide Association Study (GWAS) and used Mendelian Randomisation (MR) to test causal pathways. GWAS indicated a small but significant SNP-based heritability (4.4%), identifying one variant (rs429358) in APOE at genome-wide significance (P < 5e-8). MR provided evidence for a causal role of higher BMI on higher fall risk even in the absence of adverse metabolic consequences. Depression and neuroticism predicted higher risk of falling, whilst higher hand grip strength and physical activity were protective. Our findings suggest promoting lower BMI, higher physical activity as well as psychological health is likely to reduce falls.

Causal association of epigenetic aging and osteoporosis: a bidirectional Mendelian randomization study

BACKGROUND

The relationship between aging and osteoporosis is well established. However, the relationship between the body's physiological age, i.e. epigenetic age, and osteoporosis is not known. Our goal is to analyze the bidirectional causal relationship between epigenetic clocks and osteoporosis using a bidirectional Mendelian randomization study.

METHODS

We used SNPs closely associated with GrimAge, Hannum, PhenoAge, and HorvathAge in epigenetic age and SNPs closely associated with femoral neck bone mineral density, lumbar spine bone mineral density, and forearm bone mineral density as instrumental variables, respectively, using the inverse variance weighting method and several other MR methods to assess the bidirectional causal relationship between epigenetic age and osteoporosis.

RESULT

There was no evidence of a clear causal relationship of epigenetic age (GrimAge, Hannum, PhenoAge, and HorvathAge) on femoral neck bone mineral density, lumbar spine bone mineral density, and forearm bone mineral density. In reverse Mendelian randomization analysis showed a significant causal effect of lumbar spine bone mineral density on GrimAge: odds ratio (OR) = 0.692, 95% confidence interval (CI) = (0.538-0.890), p = 0.004. The results suggest that a decrease in lumbar spine bone mineral density promotes an acceleration of GrimAge.

CONCLUSION

There was no significant bidirectional causal relationship between epigenetic age and osteoporosis A decrease in lumbar spine bone density may lead to an acceleration of the epigenetic clock "GrimAge". Our study provides partial evidence for a bidirectional causal effect between epigenetic age and Osteoporosis.

[GDF5: a therapeutic candidate for combating sarcopenia]

Sarcopenia is a complex age-related muscular disease affecting 10 to 16 % of people over 65 years old. It is characterized by excessive loss of muscle mass and strength. Despite a plethora of studies aimed at understanding the physiological mechanisms underlying this pathology, the pathophysiology of sarcopenia remains poorly understood. To date, there is no pharmacological treatment for this disease. In this context, our team develop therapeutic approaches based on the GDF5 protein to counteract the loss of muscle mass and function in various pathological conditions, including sarcopenia. After deciphering one of the molecular mechanisms governing GDF5 expression, we have demonstrated the therapeutic potential of this protein in the preservation of muscle mass and strength in aged mice.

The Health, Aging, and Body Composition (Health ABC) Study-Ground-Breaking Science for 25 Years and Counting

BACKGROUND

The Health, Aging, and Body Composition Study is a longitudinal cohort study that started just over 25 years ago. This ground-breaking study tested specific hypotheses about the importance of weight, body composition, and weight-related health conditions for incident functional limitation in older adults.

METHODS

Narrative review with analysis of ancillary studies, career awards, publications, and citations.

RESULTS

Key findings of the study demonstrated the importance of body composition as a whole, both fat and lean mass, in the disablement pathway. The quality of the muscle in terms of its strength and its composition was found to be a critical feature in defining sarcopenia. Dietary patterns and especially protein intake, social factors, and cognition were found to be critical elements for functional limitation and disability. The study is highly cited and its assessments have been widely adopted in both observational studies and clinical trials. Its impact continues as a platform for collaboration and career development.

CONCLUSIONS

The Health ABC provides a knowledge base for the prevention of disability and promotion of mobility in older adults.

U-shaped association between plasma C-peptide and sarcopenia: A cross-sectional study of elderly Chinese patients with diabetes mellitus

Limited research exists regarding the relationship between fasting plasma C-peptide levels and sarcopenia. As a result, our study aimed to examine this association in elderly Chinese diabetic patients. This cross-sectional study included 288 elderly patients with diabetes mellitus from the Fourth People's Hospital in Guiyang who were enrolled prospectively between March 2020 and February 2023. The independent variable of interest was fasting plasma C-peptide, while the dependent variable was sarcopenia. Data on several covariates, including demographic factors, lifestyle habits, co-morbidities, anthropometric indicators, and laboratory indicators, were also collected. Of the 288 participants, 27.43% (79/288) had sarcopenia. After adjusting for potential confounding variables, we found a U-shaped association between fasting plasma C-peptide levels and sarcopenia, with inflection points identified at approximately 774 pmol/L and 939 mmol/L. Within the range of 50-744 pmol/L, each 100 pmol/L increase in CysC was associated with a 37% decrease in the odds of sarcopenia (odds ratio [OR], 0.63; 95% confidence interval [CI], 0.49 to 0.83; P < 0.001). Additionally, within the range of 939-1694 pmol/L, each 100 pmol/L increase in fasting plasma C-peptide was associated with a 76% increase in the odds of sarcopenia (odds ratio [OR], 1.76; 95% confidence interval [CI], 1.11 to 2.81; P = 0.017). Our study revealed a U-shaped association between fasting plasma C-peptide levels and the likelihood of sarcopenia, with lower risk in the range of 774-939 pmol/L. These findings may assist in the development of more effective prevention and treatment strategies for sarcopenia in elderly diabetic patients.

The phenotypic and genotypic association of grip strength with frailty, physical performance and functional limitations over time in older adults

OBJECTIVES

To replicate the phenotypic associations of grip strength with frailty, physical performance and functional limitations in older adults for longer follow-up periods and to examine whether these associations are due to shared genetic factors.

METHODS

In total 2,262 participants 55 years and older with follow-up data up to 23 years (Nobservations = 8,262) from the Longitudinal Aging Study Amsterdam were included. Weighted polygenic risk scores for grip strength (PRS-GS) were built using the genome-wide meta-analysis results from UK Biobank as reference. Grip strength was measured two times on each hand using a dynamometer. Frailty index (FI) and frailty phenotype were operationalised following standard procedures. Performance tests included a timed walk test, a repeated chair stands test and put on-take off cardigan test. Functional limitations were assessed using a questionnaire with six items.

RESULTS

Higher grip strength was phenotypically associated with lower FI (b = -0.013, 95% CI (-0.016, -0.009)), better physical performance (b = 0.040, 95% CI (0.026, 0.054)) and less functional limitations (OR = 0.965, 95% CI (0.954, 0.977)) over time for follow-up periods up to 23 years. However, PRS-GS was not associated with any of the traits.

CONCLUSION

The phenotypic associations between grip strength, frailty, physical performance and functional limitations were replicated for follow-up periods up to 23 years. However, the associations between the traits could not be explained by shared genetics potentially indicating a more relevant involvement of non-genetic factors.

A Bidirectional Mendelian Randomization Study of Sarcopenia-Related Traits and Knee Osteoarthritis

Background

With the development of population aging worldwide, sarcopenia and knee osteoarthritis (KOA), two age-related diseases, will continue to impose increasing medical and economic burdens on the society. Previous studies have discovered an association between the two, but the causality remains controversial, and it is difficult to eliminate confounding factors. Therefore, a Mendelian randomization (MR) study was conducted to overcome these confounding factors and investigate the causal relationship between sarcopenia and KOA.

Objective

The present work focused on assessing the causality between KOA and sarcopenia, so as to provide new strategies to prevent and treat these two conditions in clinic.

Methods

We registered the title with PROSPERO (ID: CRD42023421096). The two-sample bidirectional MR analysis was conducted in two steps, with sarcopenia being the exposure whereas KOA being the outcome in the first step, and vice versa in the second step. Genome-wide association studies (GWAS) data on low hand-grip strength (n=256,523), walking pace (n=459,915), appendicular lean mass (ALM, n=450,243), and KOA (n=403,124) were obtained from the UK Biobank. Methods such as the inverse variance weighted (IVW) and weighted median were utilized for assessing the causality of KOA with sarcopenia, and sensitivity analyses were also conducted.

Results

In the main MR analysis using the IVW method, evidence suggested that low hand-grip strength, walking pace, and ALM had adverse effects on KOA (p-value 0.0001, odds ratio (OR) 1.4569, 95% confidence interval (CI) 1.2007-1.7677 for low hand-grip strength; p-value 0.0003, OR 1.1500, 95% CI 1.050-1.183 for ALM; p-value 5.29E-19, OR 0.0932, 95% CI 0.0553-0.1572 for walking pace). However, there was no causality of KOA with sarcopenia in the opposite direction.

Conclusion

Our study suggests an obvious unidirectional causality of KOA with sarcopenia, and supports the notion that patients with sarcopenia are more susceptible to the development of KOA.

Causal relationship between sarcopenia and osteoarthritis: a bi-directional two-sample mendelian randomized study

BACKGROUND

Previous studies have shown that osteoarthritis (OA) and sarcopenia (SP) are closely related to each other, but the causal relationships between them have not been established. The aim of this study was to investigate the causal associations between OA and SP via a bi-directional Mendelian randomization (MR) approach.

METHODS

A bi-directional two-sample MR was adopted to research the causal relationship between SP and OA. The instrumental variables for SP and four types of OA: KOA, HOA, total knee replacement (TKR) and total hip replacement (THR) were derived from published large genome-wide association studies (GWAS). The inverse variance weighted (IVW), MR-Egger and weighted median estimator (WME) methods were used to estimate bi-directional causal effects.

RESULTS

Low grip strength (GS) did not have a causal effect on four types of OA (KOA: OR = 1.205, 95% CI 0.837-1.734, p = 0.316; HOA: OR = 1.090, 95% CI 0.924-1.609, p = 0.307; TKR: OR = 1.190, 95% CI 1.084-1.307, p = 0.058; THR: OR = 1.035, 95% CI 0.792-1.353, p = 0.798), while appendicular lean mass (ALM) had a causal effect on four types of OA (KOA: OR = 1.104, 95% CI 1.041-1.171, p = 0.001; HOA: OR = 1.151, 95% CI 1.071-1.237, p < 0.001; TKR: OR = 1.114, 95% CI 1.007-1.232, p < 0.001; THR: OR = 1.203, 95% CI 1.099-1.316, p < 0.001). In the reverse direction, KOA or HOA did not have a significant causal effect on both GS and ALM (KOA-GS: OR = 1.077, 95% CI 0.886-1.309, p = 0.458; KOA-ALM: Beta = 0.004, p = 0.892; HOA-GS: OR = 1.038, 95% CI 0.981-1.099, p = 0.209; HOA-ALM: Beta = - 0.017, p = 0.196; TKR-GS: OR = 0.999, 95% CI 0.739-1.351, p = 0.997; TKR-ALM: Beta = 0.018, p = 0.501; THR-GS: OR = 1.037, 95% CI 0.978-1.101, p = 0.222; THR-ALM: Beta = - 0.023, p = 0.081).

CONCLUSIONS

The present study suggests that SP may have a causal effect on OA through changes in muscle composition rather than muscle strength, while little evidence was provided for the causal effect of OA on SP.

Relationship between DNA methylation changes and skeletal muscle mass

BACKGROUND

Sarcopenia is a disease diagnosed in the elderly. In patients with sarcopenia, the muscle mass decreases every year. The occurrence of sarcopenia is greatly affected by extrinsic factors such as eating habits, exercise, and lifestyle. The present study aimed to determine the relationship between muscle mass traits and genes affected by epigenetic factors with three different adjustment methods using Korean Genome and Epidemiology Study (KOGES) data.

RESULTS

We conducted a demographic study and DNA methylation profiling by three studies according to the muscle mass index (MMI) adjustment methods: appendicular skeletal muscle mass divided by body weight (MMI1); appendicular skeletal muscle mass divided by square of height (MMI2); appendicular skeletal muscle mass divided by BMI (MMI3). We analyzed differentially methylated regions (DMRs) for each group. We then restricted our subjects to be top 30% (T30) and bottom 30% (B30) based on each MMI adjustment method. Additionally, we performed enrichment analysis using PathfindR to evaluate the relationship between identified DMRs and sarcopenia. A total of 895 subjects were included in the demographic study. The values of BMI, waist, and hip showed a significant difference in all three groups. Among 446 participants, 44 subjects whose DNA methylation profiles were investigated were included for DNA methylation analysis. The results of enrichment analysis showed differences between groups. In the women group through MMI1 method, only the glutamatergic synapse pathway showed a significant result. In the men group through MMI2 method, the adherens junction pathway was the most significant. Women group through MMI2 method showed similar results, having an enriched Rap1 signaling pathway. In men group through MMI3 method, the Fc epsilon RI signaling pathway was the most enriched. Particularly, the notch signaling pathway was significantly enriched in women group through MMI3 method.

CONCLUSION

This study presents results about which factor should be concerned first in muscle mass index (MMI) adjustment. The present study suggested that GAB2 and JPH3 in MMI1 method, HLA-DQB1 and TBCD in MMI2 method, GAB2, NDUFB4 and ISPD in MMI3 method are potential genes that can have an impact on muscle mass. It could enable future epigenetic studies of genes based on annotation results. The present study is a nationwide study in Korea with the largest size up to date that compares adjustment indices for MMI in epigenetic research.

Association Between Autoimmune Diseases and Sarcopenia: A Two-Sample Mendelian Randomization Study

Purpose

Observational studies have reported that autoimmune diseases are closely related to sarcopenia, but the causalities of autoimmune diseases with sarcopenia have not been established. We conducted this Mendelian randomization (MR) study to reveal the causal associations of overall autoimmune disease and five common autoimmune diseases with sarcopenia-related traits.

Methods

The publicly available summary-level data of autoimmune diseases and three sarcopenia-related traits were used for analysis. The causal effects of autoimmune diseases on sarcopenia-related traits were first identified in discovery samples using the inverse-variance-weighted method as the primary method, and the robustness of results was examined by additional sensitivity analyses. Replication MR analyses were then conducted using replication samples of five autoimmune diseases. Finally, the possibility of reverse causation was assessed by reverse MR analyses.

Results

In both the discovery and replication samples, we identified potential causal effects of rheumatoid arthritis (RA) on appendicular lean mass (ALM) and low grip strength (OR = 0.979, 95% CI: 0.964-0.995 for ALM; OR = 1.042, 95% CI: 1.013-1.072 for low grip strength), but not on walking pace. We also found that inflammatory bowel disease (IBD) and type 1 diabetes (T1D) were only causally negatively associated with ALM in the discovery stage (OR = 0.986, 95% CI: 0.974-0.999 for IBD; OR = 0.987, 95% CI: 0.975-0.999 for T1D), whereas systemic lupus erythematosus, multiple sclerosis, and overall autoimmune disease were not associated with any of the three sarcopenia-related traits. Additionally, reverse MR analysis only found an association between walking pace and overall autoimmune disease, but this association did not remain in the weighted-median method.

Conclusion

This study demonstrates that RA is causally associated with low grip strength and reduced ALM, and that IBD and T1D may be causally negatively related to ALM.

Depression and sarcopenia: a Mendelian randomization analysis

BACKGROUND

The association between depression and sarcopenia has been reported in observational studies but the causality of depression on sarcopenia remained unknown. We aimed to assess the causal effect between major depressive disorder (MDD) and sarcopenia using the two-sample Mendelian randomization (MR) method.

METHODS

A set of genetics instruments were used for analysis, derived from publicly available genetic summary data. Clinically, appendicular lean mass (ALM) and low hand grip strength (LHGS) have been widely used for the diagnosis of sarcopenia. Inverse-variance weighted method, weighted median method, MR-Egger, MR Pleiotropy RESidual Sum and Outlier test were used for the bidirectional MR analyses.

RESULTS

No evidence for an effect of MDD on sarcopenia risk was found. MDD was not associated with ALM [effect = -0.17 (-0.60 to 0.27), P = 0.449] and LHGS [effect = 0.24 (-0.46 to 0.93), P = 0.506]. Sarcopenia was not associated with MDD [ALM: odds ratio (OR) = 0.999 (0.996-1.001), P = 0.374; LHGS: OR = 0.999 (0.996-1.002), P = 0.556].

CONCLUSION

MDD and Sarcopenia might mutually have no causal effect on each other.

Sarcopenia, osteoporosis and frailty

Muscles and bones are intricately connected tissues displaying marked co-variation during development, growth, aging, and in many diseases. While the diagnosis and treatment of osteoporosis are well established in clinical practice, sarcopenia has only been classified internationally as a disease in 2016. Both conditions are associated with an increased risk of adverse health outcomes such as fractures, dysmobility and mortality. Rather than focusing on one dimension of bone or muscle mass or weakness, the concept of musculoskeletal frailty captures the overall loss of physiological reserves in the locomotor system with age. The term osteosarcopenia in particular refers to the double jeopardy of osteoporosis and sarcopenia. Muscle-bone interactions at the biomechanical, cellular, paracrine, endocrine, neuronal or nutritional level may contribute to the pathophysiology of osteosarcopenia. The paradigm wherein muscle force controls bone strength is increasingly facing competition from a model centering on the exchange of myokines, osteokines and adipokines. The most promising results have been obtained in preclinical models where common drug targets have been identified to treat these conditions simultaneously. In this narrative review, we critically summarize the current understanding of the definitions, epidemiology, pathophysiology, and treatment of osteosarcopenia as part of an integrative approach to musculoskeletal frailty.

Genes and Athletic Performance: The 2023 Update

Phenotypes of athletic performance and exercise capacity are complex traits influenced by both genetic and environmental factors. This update on the panel of genetic markers (DNA polymorphisms) associated with athlete status summarises recent advances in sports genomics research, including findings from candidate gene and genome-wide association (GWAS) studies, meta-analyses, and findings involving larger-scale initiatives such as the UK Biobank. As of the end of May 2023, a total of 251 DNA polymorphisms have been associated with athlete status, of which 128 genetic markers were positively associated with athlete status in at least two studies (41 endurance-related, 45 power-related, and 42 strength-related). The most promising genetic markers include the AMPD1 rs17602729 C, CDKN1A rs236448 A, HFE rs1799945 G, MYBPC3 rs1052373 G, NFIA-AS2 rs1572312 C, PPARA rs4253778 G, and PPARGC1A rs8192678 G alleles for endurance; ACTN3 rs1815739 C, AMPD1 rs17602729 C, CDKN1A rs236448 C, CPNE5 rs3213537 G, GALNTL6 rs558129 T, IGF2 rs680 G, IGSF3 rs699785 A, NOS3 rs2070744 T, and TRHR rs7832552 T alleles for power; and ACTN3 rs1815739 C, AR ≥21 CAG repeats, LRPPRC rs10186876 A, MMS22L rs9320823 T, PHACTR1 rs6905419 C, and PPARG rs1801282 G alleles for strength. It should be appreciated, however, that elite performance still cannot be predicted well using only genetic testing.

Investigating association between gut microbiota and sarcopenia-related traits: a Mendelian randomization study

Background

Observational studies have indicated a potential link between gut microbiota and sarcopenia. However, the underlying mechanisms and a causal relationship have not been established. Thus, the objective of this study is to examine the possible causal association between gut microbiota and sarcopenia-related traits, including low hand-grip strength and appendicular lean mass (ALM), to shed light on the gut-muscle axis.

Methods

To investigate the potential impact of gut microbiota on low hand-grip strength and ALM, we utilized a two-sample Mendelian randomization (MR) approach. Summary statistics were obtained from genome-wide association studies of gut microbiota, low hand-grip strength, and ALM. The primary MR analysis employed the random-effects inverse-variance weighted (IVW) method. To assess the robustness, we conducted sensitivity analyses using the MR pleiotropy residual sum and outlier (MR-PRESSO) test to detect and correct for horizontal pleiotropy, as well as the MR-Egger intercept test and leave-one-out analysis.

Results

Alcaligenaceae, Family XIII, and Paraprevotella were positively associated with the risk of low hand-grip strength (P-values < 0.05). Streptococcaceae were negatively associated with low hand-grip strength (P-values < 0.05). Eight bacterial taxa (Actinomycetales, Actinomycetaceae, Bacteroidaceae, Porphyromonadaceae, Prevotellaceae, Bacteroides, Marvinbryantia, and Phascolarctobacterium) were associated with a higher risk of ALM (P-values < 0.05). Eubacterium fissicatena group was negatively associated with ALM (P-values < 0.05).

Conclusion

We found several gut microbiota components causally associated with sarcopenia-related traits. Our findings provided insights into novel strategies for the prevention and treatment of sarcopenia through the regulation of the gut microbiota, contributing to a better understanding of the gut-muscle axis.

Urinary antibiotic exposure and low grip strength risk in community-dwelling elderly Chinese by gender and age

Emerging studies have shown that environmental contaminants were related to decreased handgrip strength. Nevertheless, no prior research has investigated the relationship of exposure to environmental antibiotics with grip strength. Thus, we explored the relationship between urinary antibiotic burden and grip strength among the elderly in China. This study consisted of 451 men and 539 women from the baseline survey of a cohort study. Commonly used antibiotics for humans and animals were detected in 990 urine samples through a biomonitoring method. Grip strength was measured by an electronic dynamometer. We examined the associations of antibiotic exposure with low grip strength (LGS), grip strength, and grip strength index, respectively. Results suggested that 34.9% of participants developed LGS, and 93.0% of individuals were exposed to 1-10 antibiotics. Among women, oxytetracycline (Quartile 2: odds ratio: 2.97, 95% confidence interval: 1.36-6.50), florfenicol (Quartile 3: 2.60 [1.28-5.27]), fluoroquinolones (Quartile 4: 1.88 [1.07-3.30]), and chloramphenicols (Quartile 3: 2.73 [1.35-5.51]) could enhance LGS risk. Among men, ofloxacin (Quartile 2: 3.32 [1.45-7.59]) increased LGS risk, whereas tetracycline (Quartile 2: 0.31 [0.11-0.88]) was implicated in reduced LGS risk. In participants < 70 years, ofloxacin (Quartile 2: 3.00 [1.40-6.42]) could increase LGS risk. For participants who were 70 years of age or older, veterinary antibiotics (Quartile 3: 1.73 [1.02-2.94]) were linked to a 73% increased risk of LGS. Our findings suggested that antibiotics mainly pertained to LGS, and there were gender and age disparities in associations between antibiotic exposure and muscle strength indicators in the elderly Chinese population.

Association between sugar-sweetened beverage consumption frequency and muscle strength: results from a sample of Chinese adolescents

BACKGROUND

Although sugar-sweetened beverage consumption has become an important and widespread concern, there are few studies on the association between sugar-sweetened beverage consumption frequency and muscle strength in Chinese adolescents. The objective of this study was to analyze the association between sugar-sweetened beverage consumption frequency and muscle strength in Chinese adolescents.

METHODS

A stratified whole-group sampling method was used to survey 25,893 adolescents aged 13-15 years old in China for sugar-sweetened beverage consumption frequency and muscle strength for grip strength and standing long jump. The subjects' basic information, body mass index (BMI), and covariates were investigated. The association between sugar-sweetened beverage consumption frequency and muscle strength was analyzed by multivariate logisitc regression analysis.

RESULTS

The proportions of Chinese adolescents who consumed sugar-sweetened beverage ≥ 3 times/week, 1-2 times/week, and < 1 time/week were 12.23%, 52.79%, and 34.98%, respectively. The differences in sugar-sweetened beverage consumption frequency were statistically significant when compared across gender, parental education, duration of physical activity, snacks, and mode of commuting to school (χ² values = 228.570, 51.422, 275.552, 3165.656, 10.988, P < 0.01). Logistic regression analysis showed that overall Chinese adolescents with sugary drinks 1-2 times/week (OR = 1.207, 95% CI:1.132-1.287) and sugary drinks ≥ 3 times/week (OR = 1.771, 95% CI:1.611-1.947) were associated with lower muscle strength compared to sugary drinks < 1 time/week showed a positive association (P < 0.01). The same trend was found for boys and girls.

CONCLUSION

Chinese adolescents' sugar-sweetened beverage consumption is common, and high-frequency sugar-sweetened beverage consumption is associated with lower muscle strength. In the future, we should control the use of sugar-sweetened beverages and increase muscular strength training in Chinese adolescents to promote healthy growth.

APP in the Neuromuscular Junction for the Development of Sarcopenia and Alzheimer's Disease

Sarcopenia, an illness condition usually characterized by a loss of skeletal muscle mass and muscle strength or function, is often associated with neurodegenerative diseases, such as Alzheimer's disease (AD), a common type of dementia, leading to memory loss and other cognitive impairment. However, the underlying mechanisms for their associations and relationships are less well understood. The App, a Mendelian gene for early-onset AD, encodes amyloid precursor protein (APP), a transmembrane protein enriched at both the neuromuscular junction (NMJ) and synapses in the central nervous system (CNS). Here, in this review, we highlight APP and its family members' physiological functions and Swedish mutant APP (APP_swe)'s pathological roles in muscles and NMJ. Understanding APP's pathophysiological functions in muscles and NMJ is likely to uncover insights not only into neuromuscular diseases but also AD. We summarize key findings from the burgeoning literature, which may open new avenues to investigate the link between muscle cells and brain cells in the development and progression of AD and sarcopenia.

Genome-wide association study of cerebellar white matter microstructure and genetic overlap with common brain disorders

BACKGROUND

The cerebellum is recognized as being involved in neurocognitive and motor functions with communication with extra-cerebellar regions relying on the white matter integrity of the cerebellar peduncles. However, the genetic determinants of cerebellar white matter integrity remain largely unknown.

METHODS

We conducted a genome-wide association analysis of cerebellar white matter microstructure using diffusion tensor imaging data from 25,415 individuals from UK Biobank. The integrity of cerebellar white matter microstructure was measured as fractional anisotropy (FA) and mean diffusivity (MD). Identification of independent genomic loci, functional annotation, and tissue and cell-type analysis were conducted with FUMA. The linkage disequilibrium score regression (LDSC) was used to calculate genetic correlations between cerebellar white matter microstructure and regional brain volumes and brain-related traits. Furthermore, the conditional/conjunctional false discovery rate (condFDR/conjFDR) framework was employed to identify the shared genetic basis between cerebellar white matter microstructure and common brain disorders.

RESULTS

We identified 11 genetic loci (P < 8.3 × 10^-9) and 86 genes associated with cerebellar white matter microstructure. Further functional enrichment analysis implicated the involvement of GABAergic neurons and cholinergic pathways. Significant polygenetic overlap between cerebellar white matter tracts and their anatomically connected or adjacent brain regions was detected. In addition, we report the overall genetic correlation and specific loci shared between cerebellar white matter microstructural integrity and brain-related traits, including movement, cognitive, psychiatric, and cerebrovascular categories.

CONCLUSIONS

Collectively, this study represents a step forward in understanding the genetics of cerebellar white matter microstructure and its shared genetic etiology with common brain disorders.