The causal relationship between sarcopenia-related traits and ischemic stroke: Insights from univariable and multivariable Mendelian randomization analyses.
The causal relationship between sarcopenia-related traits and ischemic stroke (IS) remains poorly understood. This study aimed to explore the causal impact of sarcopenia-related traits on IS and to identify key mediators of this association.
We conducted univariable, multivariable two-sample, and two-step Mendelian randomization (MR) analyses using genome-wide association study (GWAS) data. This included data for appendicular lean mass (ALM), hand grip strength (HGS), and usual walking pace (UWP) from the UK Biobank, and IS data from the MEGASTROKE consortium. Additionally, 21 candidate mediators were analyzed based on their respective GWAS data sets.
Each 1-SD increase in genetically proxied ALM was associated with a 7.5% reduction in the risk of IS (95% CI: 0.879-0.974), and this correlation remained after controlling for levels of physical activity and adiposity-related indices. Two-step MR identified that six mediators partially mediated the protective effect of higher ALM on IS, with the most significant being coronary heart disease (CHD, mediating proportion: 39.94%), followed by systolic blood pressure (36.51%), hypertension (23.87%), diastolic blood pressure (15.39%), type-2 diabetes mellitus (T2DM, 12.71%), and low-density lipoprotein cholesterol (7.97%).
Our study revealed a causal protective effect of higher ALM on IS, independent of physical activity and adiposity-related indices. Moreover, we found that higher ALM could reduce susceptibility to IS partially by lowering the risk of vascular risk factors, including CHD, hypertension, T2DM, and hyperlipidemia. In brief, we elucidated another modifiable factor for IS and implied that maintaining sufficient muscle mass may reduce the risk of such disease.
Song J
，Zhou D
，Li J
，Wang M
，Jia L
，Lan D
，Song H
，Ji X
，Meng R
... -
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Causal associations of sarcopenia-related traits with cardiometabolic disease and Alzheimer's disease and the mediating role of insulin resistance: A Mendelian randomization study.
The causal influence of sarcopenia on cardiometabolic disease and Alzheimer's disease and whether and to what extent insulin resistance plays a mediating role therein were unclear. We performed two-step, two-sample Mendelian randomization applying genetic instruments of sarcopenia-related traits based on GWASs from the UK Biobank (up to 461,026 European participants) to examine their causal associations with six cardiometabolic diseases and Alzheimer's disease extracted from large-scale European descent GWASs with adjustment for body fat percentage and physical activity, and to assess proportions of the causal effects mediated by insulin resistance. Genetic instruments of insulin resistance were derived from the GWASs by Meta-Analyses of Glucose and Insulin-related traits Consortium and Global Lipids Genetics Consortium. Each 1-SD lower grip strength, appendicular lean mass (ALM) and whole-body lean mass (WBLM), as well as lower walking pace, were causally associated with higher risks of diabetes (odds ratio [OR] range: 1.20 [95% confidence interval: 1.10-1.32] for ALM to 2.30 [1.14-4.68] for walking pace), nonalcoholic fatty liver disease ([NAFLD], 1.33 [1.08-1.64] for ALM to 2.30 [1.02-5.18] for grip strength), hypertension (1.12 [1.05-1.20] for ALM to 4.43 [2.68-7.33] for walking pace), coronary heart disease ([CHD], 1.20 [1.13-1.27] for ALM to 2.73 [1.84-4.05] for walking pace), myocardial infarction ([MI], 1.18 [1.11-1.25] for ALM to 2.47 [1.63-3.73] for walking pace), small vessel stroke (1.25 [1.15-1.37] for ALM to 1.29 [1.10-1.52] for WBLM), and Alzheimer's disease (1.10 [1.05-1.15] for ALM to 1.28 [1.19-1.38] for WBLM). These causal associations were largely independent of body fat percentage and physical activity. Insulin resistance mediated 16%-34% of the effect of grip strength and 7%-28% of the effect of ALM on diabetes, NAFLD, hypertension, CHD, and MI. The direct effect of WBLM on diabetes diminished toward null with adjustment for insulin resistance. We found no evidence that insulin resistance was on the causal pathways from walking pace to the studied disease outcomes. Causal findings from the inverse-variance weighted method were validated by sensitivity analyses. These findings support improving sarcopenia-related traits as precautions against major cardiometabolic diseases and Alzheimer's disease, with particular emphasis on insulin resistance as a target in the intervention of sarcopenia-related cardiometabolic risk.
Ye C
，Kong L
，Wang Y
，Zheng J
，Xu M
，Xu Y
，Li M
，Zhao Z
，Lu J
，Chen Y
，Wang W
，Ning G
，Bi Y
，Wang T
... -
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Bidirectional two-sample mendelian randomization analysis identifies causal associations between age at menarche and sarcopenia-related traits.
Observational studies have shown that the age of menarche is associated with sarcopenia, but confounding factors make the causal relationship difficult to infer.
Therefore, we conducted a bidirectional two-sample Mendelian randomized (MR) analysis to evaluate the potential causal relationship between age at menarche and sarcopenia-related traits (hand grip strength, lean mass, walking pace).
We obtained the latest aggregate statistics from the Genome-wide association studies (GWAS) database on the age of menarche of 182,416 participants from ReproGen, the appendicular lean mass of 244,730 participants from EMBL's European Bioinformatics Institute, the left-hand grip strength of 401,026 participants, the right-hand grip strength of 461,089 participants and the usual walking pace of 459,915 participants from the UK Biobank. The inverse variance weighting (IVW) method and other MR methods were used to evaluate the bidirectional causal relationship between the age of menarche and sarcopenia.
The forward MR results showed that the age of menarche predicted by the gene was positively correlated with left-hand grip strength (IVWβ=0.041, P = 2.00 × 10-10), right-hand grip strength (IVWβ=0.053, P = 1.97 × 10-18), appendicular lean mass (IVWβ=0.012, P = 4.38 × 10-13) and usual walking pace (IVWβ=0.033, P = 1.62 × 10-8).In the reverse MR analysis, we also found that the usual walking pace was positively correlated with the age of menarche predicted by genes (IVWβ=0.532, P = 1.65 × 10-4). Still, there was no causal relationship between grip strength and appendicular lean mass and the age at menarche.
Our results show that earlier menarche will increase the risk of sarcopenia. In addition, people with higher muscle function tend to have menarche later. These findings may provide a reference for prevention strategies and interventions for menarche in advance and sarcopenia.
Fan W
，Gu P
，Pu B
，Yue D
，Xin Q
，Zheng X
，Zeng Z
，Fan S
... -
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Causal relationship between sarcopenia with osteoarthritis and the mediating role of obesity: a univariate, multivariate, two-step Mendelian randomization study.
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.
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.
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%).
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.
Jin Z
，Wang R
，Jin L
，Wan L
，Li Y
... -
《BMC Geriatrics》
ResearchGate
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钛学术
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