Physical Activity and Risks of Cardiovascular Diseases: A Mendelian Randomization Study

Sexual Dimorphism in Cardiometabolic Diseases: From Development to Senescence and Therapeutic Approaches

The global incidence and prevalence of cardiometabolic disorders have risen significantly in recent years. Although lifestyle choices in adulthood play a crucial role in the development of these conditions, it is well established that events occurring early in life can have an important effect. Recent research on cardiometabolic diseases has highlighted the influence of sexual dimorphism on risk factors, underlying mechanisms, and response to therapies. In this narrative review, we summarize the current understanding of sexual dimorphism in cardiovascular and metabolic diseases in the general population and within the framework of the Developmental Origins of Health and Disease (DOHaD) concept. We explore key risk factors and mechanisms, including the influence of genetic and epigenetic factors, placental and embryonic development, maternal nutrition, sex hormones, energy metabolism, microbiota, oxidative stress, cell death, inflammation, endothelial dysfunction, circadian rhythm, and lifestyle factors. Finally, we discuss some of the main therapeutic approaches, responses to which may be influenced by sexual dimorphism, such as antihypertensive and cardiovascular treatments, oxidative stress management, nutrition, cell therapies, and hormone replacement therapy.

MVPA as the most influential factor for myocardial infarction through Bayesian Mendelian randomization among 11 behaviors

PURPOSE

The causal associations between behavioral factors (BF) and myocardial infarction (MI), as well as the potential mediators and dose-response relationships, are incompletely clear. Therefore, this study aimed to evaluate the association of 11 BF with MI.

METHODS

We used two-sample Mendelian randomization (2SMR) to investigate he associations between BF and MI and applied a two-sample multivariable MR approach based on Bayesian model averaging (MR-BMA) to prioritize the BF identified by 2SMR. For significant BF, we conducted extra conducted mediation analysis and restricted cubic spline (RCS) analysis to reveal potential mediating pathways and their dose-response relationships. Furthermore, we conducted replication analysis and meta-analysis to further support the results.

RESULTS

Among 11 BF, 2SMR identified 3 BF that were significantly associated with MI. Among them, MR-BMA identified moderate to vigorous intensity physical activity (MVPA) (Marginal inclusion probability (MIP) = 0.77) as the most influential factor. A potential mechanism underlying the MVPA-MI association was waist-hip ratio (WHR, 7.26%). RCS analysis further revealed that an MVPA of 1094-2043 MET minutes/week was associated with the lowest risk of MI. Finally, replication analysis and meta-analysis further supported the 3 BF and identified an extra association between tea intake and MI risk (Meta: OR = 0.991, P = .003).

CONCLUSION

Of the 11 BF, MVPA was the most influential factor independently associated with the reduced risk of MI, with WHR mediating this association. At least 39 minutes of MVPA per day is recommended to reduce the risk of MI. In addition, tea intake is a potential protective factor for MI that warrants further investigation. Key messages What is already known on this topic?  Previous studies have shown an association between behavioral factors and the risk of myocardial infarction (MI). However, the exact causal relationship, which behavioral factors is most influential for MI, and the potential dose-response relationship are incompletely clear. Mendelian randomization can provide genetic evidence of causal associations and reveal the underlying mechanisms. What this study adds?  This study provides novel genetic evidence that smoking initiation, leisure sedentary time, and moderate to vigorous intensity physical activity (MVPA) are associated with MI. MVPA is the most influential factor. Only MVPA is independently associated with MI, and waist-to-hip ratio mediated the association. In addition, we found that at least 39 minutes of MVPA per day resulted in the greatest reduction in MI. Finally, we also found a potential protective effect of tea drinking on MI. How this study might affect research, practice, or policy?  This study suggests that MVPA is independently associated with MI. In addition, this provides a basis for clinical exercise intervention. Finally, these results respond to the policy that "exercise is medicine", providing new insights into the advancement of that slogan.

Is the occurrence of deep vein thrombosis related to the fracture site? A two-sample Mendelian randomization study

OBJECTIVE

Deep vein thrombosis (DVT) is a known complication of fractures. This study aimed to explore the genetic causal relationship between DVT and fracture sites.

RESEARCH DESIGN AND METHODS

The exposures analyzed in this study included fracture of femur (FFE), fracture of lower leg, including ankle (FLLA), fracture of shoulder and upper arm (FSUA), fracture of forearm (FFO), fracture of rib, sternum and thoracic spine (FRSTS) and fracture of lumbar spine and pelvis (FLSP). DVT as the outcome. A two-sample Mendelian randomization (MR) approach was employed to investigate the genetic causal relationship, and a series of sensitivity analyses were conducted.

RESULTS

The findings indicated no genetic causal relationship between FFE (p = 0.569, OR 95% CI = 1.001 [0.998-1.003]), FLLA (p = 0.371, OR 95% CI = 0.999 [0.995-1.002]), FSUA (p = 0.871, OR 95% CI = 1.000 [0.998-1.002]), FFO (p = 0.281, OR 95% CI = 1.001 [0.999-1.002]), FRSTS (p = 0.346, OR 95% CI = 0.999 [0.996-1.001]) or FLSP (p = 0.759, OR 95% CI = 1.000 [0.999-1.002]) and DVT. Sensitivity analyses reinforced the robustness.

CONCLUSIONS

This study indicate that no genetic causal relationship exists between DVT and fracture site, the observed association may be attributable to non-genetic factors.

Observational and genetic associations between cardiorespiratory fitness and age-related diseases: longitudinal analyses in the UK Biobank study

Background

Observational studies have indicated that increased cardiorespiratory fitness is associated with a decreased risk of cardiovascular disease (CVD), Alzheimer's disease (AD), and Parkinson's disease (PD). However, the causal mechanisms remain unclear. The objective of this study was to assess the role of fitness in the early detection and reduction of disease risk within the framework of predictive, preventive, and personalized medicine (PPPM/3PM).

Methods

The associations of fitness with CVD, AD, and PD were explored in a large cohort of up to 502,486 individuals between the ages of 40 and 69 years from the UK Biobank. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of CVD, AD, and PD among participants who completed a submaximal fitness test. Causality relationships were assessed via two-sample Mendelian randomization (MR).

Results

After a median of 11 years of follow-up, each 3.5 ml of O2⋅min-1⋅kg-1 increase in total body mass (equivalent to 1 metabolic equivalent of task (MET), approximately 0.5 standard deviations (SDs)) was associated with decreased risks of CVD (20.0%, 95% CI 17.6-22.3%), AD (31.9%, 95% CI 26.7-33.6%), and PD (21.2%, 95% CI 11.2-31.8%). After adjusting for obesity, the observational associations were attenuated. According to the MR analyses, fitness was associated with PD (OR IVW 0.937, 95% CI 0.897-0.978) and small vessel stroke (OR IVW 0.964, 95% CI 0.933-0.995).

Conclusion

Our results indicate that fitness has an effect on age-related diseases. Protective associations of higher fitness levels with the risk of CVD, AD, and PD were validated in this cohort study. These findings might be valuable for predicting, preventing, and reducing disease morbidity and mortality through primary prevention and healthcare in the context of PPPM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00382-4.

Physical activity and the risk of developing 8 age-related diseases: epidemiological and Mendelian randomization studies

BACKGROUND

We aimed to characterize the associations between physical activity levels and the risk of developing age-related diseases in the Coronary Artery Risk Development in Young Adults (CARDIA) study and used Mendelian randomization (MR) to assess whether there are causal relationships between physical activity levels and the risk of developing 8 age-related diseases (coronary atherosclerosis, ischemic heart disease, angina, Alzheimer's disease, hypertension, type 2 diabetes, hyperlipidemia, and venous thromboembolism).

METHODS

Based on the data available in the CARDIA, we obtained data related to five disease states: coronary heart disease, hypertension, diabetes, hyperlipidemia, and venous thromboembolism. Binary logistic regression analysis estimated the multivariable-adjusted associations between different physical activity statuses and diseases. For the MR study, we used summary-level data from a recently published genome-wide association study on physical activity (including vigorous physical activity and accelerometer-based physical activity) conducted with participants from the UK Biobank study. We selected the above 8 age-related diseases as our outcomes.

RESULTS

In the CARDIA-based analysis, the risk of developing coronary heart disease [OR (95% CI): 0.562 (0.397-0.795)], hypertension [OR (95% CI): 0.703 (0.601-0.821)], diabetes [OR (95% CI): 0.783 (0.620-0.988)], and hyperlipidemia [OR (95% CI): 0.792 (0.662-0.949)] was negatively related to physical activity status when participants achieved the physical activity target. Our MR results support a negative causal association between genetically determined vigorous physical activity levels and the risk of developing 3 age-related diseases, namely, angina, hypertension and type 2 diabetes. Moreover, our results also support a negative causal association between genetically determined accelerometer-based physical activity levels and the risk of developing angina.

CONCLUSIONS

Promotion of physical activity is likely to prevent specific age-related diseases.

Iron, copper, zinc and magnesium on rheumatoid arthritis: a two-sample Mendelian randomization study

This study aimed to elucidate the causal genetic relationships between iron, copper, zinc, magnesium, and rheumatoid arthritis (RA). A two-sample Mendelian randomization (MR) analysis was conducted using the "TwoSampleMR" and "MendelianRandomization" packages in R. The random-effects inverse variance-weighted (IVW) method was used as the primary approach. We performed sensitivity analyses to test the reliability of the results. The random-effects IVW analysis revealed that there was no genetic causal relationship between iron (P = 0.429, odds ratio [OR] 95% confidence interval [CI] = 0.919 [0.746-1.133]), copper (P = 0.313, OR 95% CI = 0.973 [0.921-1.027]), zinc (P = 0.633, OR 95% CI = 0.978 [0.891-1.073]), or magnesium (P = 0.218, OR 95% CI = 0.792 [0.546-1.148]) and RA. Sensitivity analysis verified the reliability of the results. Therefore, there is no evidence to support a causal relationship between iron, copper, zinc, and magnesium intake at the genetic level and the development of RA.

Changes in muscle strength and risk of cardiovascular disease among middle-aged and older adults in China: Evidence from a prospective cohort study

BACKGROUND

Evidence indicates that low muscle strength is associated with an increased cardiovascular diseases (CVDs) risk. However, the association between muscle strength changes based on repeated measurements and CVD incidence remains unclear.

METHODS

The study used data from the China Health and Retirement Longitudinal Study in 2011 (Wave 1), 2013 (Wave 2), 2015 (Wave 3), and 2018 (Wave 4). Low muscle strength was defined as handgrip strength <28 kg for men or <18 kg for women, or chair-rising time ≥12 s. Based on changes in muscle strength from Waves 1 to 2, participants were categorized into four groups of Normal-Normal, Low-Normal, Normal-Low, and Low-Low. CVD events, including heart disease and stroke, were recorded using a self-reported questionnaire during Waves 3 and 4 visits. Cox proportional hazards models were used to investigate the association between muscle strength changes and CVD incidence after multivariable adjustments. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) were estimated with the Normal-Normal group as the reference.

RESULTS

A total of 1164 CVD cases were identified among 6608 participants. Compared to participants with sustained normal muscle strength, the CVD risks increased progressively across groups of the Low-Normal (HR = 1.20, 95% CI: 1.01-1.43), the Normal-Low (HR = 1.35, 95% CI: 1.14-1.60), and the Low-Low (HR = 1.76, 95% CI: 1.49-2.07). Similar patterns were observed for the significant associations between muscle strength status and the incidence risks of heart disease and stroke. Subgroup analyses showed that the significant associations between CVD and muscle strength changes were consistent across age, sex, and body mass index (BMI) categories.

CONCLUSIONS

The study found that muscle strength changes were associated with CVD risk. This suggests that continuous tracking of muscle status may be helpful in screening cardiovascular risk.

Relationship between metabolic status, physical activity and cardiovascular disease in participants with obesity

OBJECTIVE

We aimed to investigate the independent and joint associations between metabolic status, PA (physical activity) and risk of CVD (cardiovascular disease) in participants with obesity.

METHODS

We included 109,301 adults with obesity free of baseline CVD enrolled from 2006 to 2010 in the UK Biobank cohort (aged 56 ± 7.9 years). Based on metabolic status, obesity was grouped into metabolically healthy obesity (MHO; free of hypertension, hypercholesterolemia and diabetes; n = 26,989; BMI 33 ± 3.3 kg/m2) and metabolically unhealthy obesity (MUO; n = 82,312; BMI 34 ± 4.0 kg/m2). PA was categorized into four groups according to moderate-to-vigorous PA (MVPA): none, low, medium, and high. Multivariable Cox regression models were used for the main analyses adjusting for sociodemographic factors, lifestyles and comorbidities.

RESULTS

There were 8,059 CVD events during a median follow-up of 8.1 years. MHO was associated with a 42% reduced risk of CVD compared with MUO (HR = 0.58, 95% CI: 0.53-0.63). A significant interaction effect between PA and metabolic status on CVD risk was found. Among MUO participants, individuals with PA had significantly decreased CVD risk when compared with no MVPA (HR = 0.87, 95% CI: 0.81-0.94 for low PA; HR = 0.85, 95% CI: 0.78-0.93 for medium PA; and HR = 0.86, 95% CI: 0.80-0.92 for high PA). The lowest CVD risk was observed in MHO & medium PA group when compared with MUO & no MVPA (HR = 0.45, 95% CI: 0.37-0.56).

CONCLUSIONS

Both MHO and any MVPA were associated with reduced risk of CVD in adults with obesity, while PA could modify the relationship between metabolic status and CVD risk.

Genomic predictors of physical activity and athletic performance

Physical activity and athletic performance are complex phenotypes influenced by environmental and genetic factors. Recent advances in lifestyle and behavioral genomics led to the discovery of dozens of DNA polymorphisms (variants) associated with physical activity and allowed to use them as genetic instruments in Mendelian randomization studies for identifying the causal links between physical activity and health outcomes. On the other hand, exercise and sports genomics studies are focused on the search for genetic variants associated with athlete status, sports injuries and individual responses to training and supplement use. In this review, the findings of studies investigating genetic markers and their associations with physical activity and athlete status are reported. As of the end of September 2023, a total of 149 variants have been associated with various physical activity traits (of which 42 variants are genome-wide significant) and 253 variants have been linked to athlete status (115 endurance-related, 96 power-related, and 42 strength-related).

Mendelian randomization for cardiovascular diseases: principles and applications

Large-scale genome-wide association studies conducted over the last decade have uncovered numerous genetic variants associated with cardiometabolic traits and risk factors. These discoveries have enabled the Mendelian randomization (MR) design, which uses genetic variation as a natural experiment to improve causal inferences from observational data. By analogy with the random assignment of treatment in randomized controlled trials, the random segregation of genetic alleles when DNA is transmitted from parents to offspring at gamete formation is expected to reduce confounding in genetic associations. Mendelian randomization analyses make a set of assumptions that must hold for valid results. Provided that the assumptions are well justified for the genetic variants that are employed as instrumental variables, MR studies can inform on whether a putative risk factor likely has a causal effect on the disease or not. Mendelian randomization has been increasingly applied over recent years to predict the efficacy and safety of existing and novel drugs targeting cardiovascular risk factors and to explore the repurposing potential of available drugs. This review article describes the principles of the MR design and some applications in cardiovascular epidemiology.

Causal association of physical activity with low back pain, intervertebral disc degeneration and sciatica: a two-sample mendelian randomization analysis study

Objective: Previous studies are insufficient to confirm a causal association between physical activity (PA) and low back pain (LBP), intervertebral disc degeneration (IDD), and sciatica. The present study used a two-sample Mendelian randomization (MR) analysis method to demonstrate whether or not there was a causal connection. Methods: First, four PA phenotypes were selected [accelerometer-based PA (average acceleration), accelerometer-based PA (acceleration fraction >425 mg), self-reported moderate-to-vigorous PA, and self-reported vigorous PA], setting thresholds for single nucleotide polymorphisms (SNPs) significantly concerned with PA p < 5 × 10-8, linkage disequilibrium (LD) r 2 < 0.01, genetic distance >5,000 kb, and F-value >10. SNPs associated with the outcome and confounding factors were then excluded using the PhenoScanncer database. Finally, after coordinating the genetic instruments from genome-wide association studies (GWAS) effect alleles for exposure and outcomes, multiplicative random effects inverse variance weighting (IVW), MR-Egger, weighted median method (WMM), and weighted mode method were used to assess exposure-outcome causality and perform sensitivity analysis on the estimated results. Results: The current study's IVW findings revealed proof of a causal connection between PA and LBP. While there was a positive causal tie between accelerometer-based PA (acceleration fraction >425 mg) and LBP [OR: 1.818, 95% CI:1.129-2.926, p = 0.012], there was a negative causal link between accelerometer-based PA (average acceleration) and LBP [OR: 0.945, 95% CI: 0.909-0.984, p = 0.005]. However causal relationship between PA and IDD or sciatica was not found. Conclusion: Increasing average PA but needing to avoid high-intensity PA may be an effective means of preventing low back pain. Although PA is not directly causally related to disc degeneration and sciatica, it can act through indirect pathways.

What can Mendelian randomization contribute to biological anthropology?

Uncovering causal relationships between exposures and outcomes can be difficult in observational studies because of the potential for confounding and reverse causation to produce biased estimates. Conversely, randomized controlled trials (RCTs) provide the strongest evidence for causality but they are not always feasible. Mendelian randomization (MR) is a method that aims to strengthen causal inference using genetic variants as proxies or instrumental variables (IVs) for exposures, to overcome the above-mentioned biases. Since allele segregation occurs at random from parents to offspring, and alleles for a trait assort independently from those for other traits, MR studies have frequently been compared to "natural" RCTs. In biological anthropology (BA) relationships between variables of interest are usually evaluated using observational data, often remaining descriptive, and other approaches to causal inference have seldom been implemented. Here, we propose the use of MR to investigate cause and effect relationships in BA studies and provide examples to show how that can be done across areas of BA relevance, such as adaptation to the environment, nutrition and life history theory. While we consider MR a useful addition to the biological anthropologist's toolbox, we advocate the adoption of a wide range of methods, affected by different types of biases, in order to better answer the important causal questions for the discipline.

Mediation of lifestyle-associated variables on the association between occupation and incident cardiovascular disease

The main aim was to examine the association between occupational groups and incident cardiovascular disease (CVD), and to which extent associations are mediated by lifestyle-associated variables (cardiorespiratory fitness, smoking, BMI, exercise, and diet). A total of 304,702 participants (mean age 42.5 yrs., 47% women), who performed a health profile assessment in Sweden between 1982 and 2019, were included in the analyses. CVD incidence was obtained from national registers. All participants were free from CVD prior to the health profile assessment. Occupational group was defined using the Swedish Standard Classification of Occupations and analyzed separately (13 different occupational groups) as well as after aggregation into four occupational groups (white-collar high-skilled, white-collar low-skilled, blue-collar high-skilled and blue-collar low-skilled). Cardiorespiratory fitness, BMI, exercise, smoking, and diet were included as mediators and analyzed separately in single models and simultaneously in one multiple mediation model. All mediation analyses were adjusted for sex, age, length of education and calendar time. White-collar high-skilled was set as reference in all analyses. Blue-collar and low-skilled occupation had a higher risk of incident CVD compared to the reference. Cardiorespiratory fitness, BMI, exercise, smoking, and diet mediated 48% to 54% of the associations between reference and the other aggregated occupational groups. In the single model, the strongest mediators were cardiorespiratory fitness, smoking and BMI. In conclusion, blue-collar and low-skilled occupations had a significantly higher risk for incident CVD compared to white-collar high-skilled workers, with the association mediated to a large extent by variation in lifestyle-associated variables.

Association between sedentary behavior, physical activity, and cardiovascular disease-related outcomes in adults-A meta-analysis and systematic review

Background

Sedentary behavior (SB) and physical activity (PA) are modifiable risk factors for cardiovascular disease (CVD); however, previous research on the effects of PA and SB on CVD has been relatively homogeneous. Our study investigated the association between PA, SB, and CVD-related outcomes.

Methods

A comprehensive search strategy was conducted in the MEDLINE, Embase, Cochrane Library, and Web of Science databases from their inception to September 2022. We identified eligible studies according to PICOS: the populations comprised healthy adults, the interventions or exposures were PA or SB, the outcomes were CVD-related outcomes, and the study designs were randomized controlled trials (RCTs) and longitudinal studies (LS). Outcomes were pooled using fixed or random effects models, and the quality of individual studies was assessed by the Cochrane Risk of Bias Instrument and the Newcastle Ottawa Scale.

Results

A total of 148 RCTs and 36 LS were included, comprising a total of 75,075 participants. The study quality was rated as low to moderate. We found an increased hazard ratio (HR) for CVD in the population with SB (HR = 1.34; 95% confidence interval [CI]: 1.26 to 1.43; I² = 52.3%; P_{heterogeneity} < 0.001, random model) and a decreased HR for CVD in those who performed long-term PA (HR = 0.71; 95% CI: 0.66 to 0.77; I² = 78.0%, P_{heterogeneity} < 0.001, random model). Long-term PA improved the lipid profiles in healthy adults; participants in this group exhibited increased high-density lipoprotein (weighted mean difference [WMD] = 2.38; 95% CI: 1.00 to 3.76; I² = 84.7%; P_{heterogeneity} < 0.001, random model), decreased triglycerides (WMD = -7.27; 95% CI: -9.68 to -4.87; I² = 0%, P_{heterogeneity} = 0.670, fixed model), and lower total-cholesterol (WMD = -6.84; 95% CI: -9.15 to -4.52; I² = 38.4%, P_{heterogeneity} < 0.001, random model).

Conclusions

Long-term SB increases the risk of CVD in healthy adults, whereas PA reduces the risk of CVD and improves indicators associated with CVD. However, the ability of PA to improve blood lipids appeared to be limited. The detailed association of SB and PA on CVD needs to be further investigated in the future.

Association between metabolically healthy obesity and risk of atrial fibrillation: taking physical activity into consideration

The modification of physical activity (PA) on the metabolic status in relation to atrial fibrillation (AF) in obesity remains unknown. We aimed to investigate the independent and joint associations of metabolic status and PA with the risk of AF in obese population. Based on the data from UK Biobank study, we used Cox proportional hazards models for analyses. Metabolic status was categorized into metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO). PA was categorized into four groups according to the level of moderate-to-vigorous PA (MVPA): none, low, medium, and high. A total of 119,424 obese participants were included for analyses. MHO was significantly associated with a 35% reduced AF risk compared with MUO (HR = 0.65, 95% CI: 0.57-0.73). No significant modification of PA on AF risk among individuals with MHO was found. Among the MUO participants, individuals with medium and high PA had significantly lower AF risk compared with no MVPA (HR = 0.84, 95% CI: 0.74-0.95, and HR = 0.87, 95% CI: 0.78-0.96 for medium and high PA, respectively). As the severity of MUO increased, the modification of PA on AF risk was elevated accordingly. To conclude, MHO was significantly associated with a reduced risk of AF when compared with MUO in obese participants. PA could significantly modify the relationship between metabolic status and risk of AF among MUO participants, with particular benefits of PA associated with the reduced AF risk as the MUO severity elevated.

Physical activities and risk of neurodegenerative diseases: A two-sample Mendelian randomization study

Objectives

Physical activity (PA) is considered beneficial in slowing the progression and improving the neurodegenerative disease prognosis. However, the association between PA and neurodegenerative diseases remains unknown. In this study, we conducted a two-sample Mendelian randomization (MR) analysis to estimate the causal association between PA phenotypes and neurodegenerative diseases.

Materials and methods

Genetic variants robustly associated with PA phenotypes, used as instrumental variables, were extracted from public genome-wide association study (GWAS) summary statistics. Neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and Alzheimer's disease (AD), were considered outcomes. GWAS information was also obtained from the most recent large population study of individuals with European ancestry. Multiple MR methods, pleiotropy tests and sensitivity analyses were performed to obtain a robust and valid estimation.

Results

We found a positive association between moderate-to-vigorous physical activities and ALS based on the inverse variance weighted MR analysis method (OR: 2.507, 95% CI: 1.218-5.160, p = 0.013). The pleiotropy test and sensitivity analysis confirmed the robustness and validity of these MR results. No causal effects of PA phenotypes were found on PD and AD.

Conclusion

Our study indicates a causal effect of PA on the risk of neurodegenerative diseases. Genetically predicted increases in self-reported moderate-to-vigorous PA participation could increase the risk of ALS in individuals of European ancestry. Precise and individualized prescriptions of physical activity should be provided to the elderly population.

Causal Relationships Between Total Physical Activity and Ankylosing Spondylitis: A Mendelian Randomization Study

Background

Currently, there is little literature about the association between physical activity (PA) and the risk of ankylosing spondylitis (AS). The present study aimed to understand the causal relationships between PA and AS.

Methods

We performed two-sample Mendelian randomization (MR) using publicly released genome-wide association studies summary statistics to estimate the causal associations of PA with AS risk. The inverse variance weighted (IVW) method was utilized as primary MR analysis. Furthermore, sensitivity, pleiotropy, and heterogeneity analyses were then conducted to assess the robustness of the findings of the present study.

Results

Results of the IVW analysis suggested a protective relationship between accelerometer-based PA and AS (average acceleration, odds ratio [OR] = 0.9995, 95% CI, 0.9988-0.9999, P = 0.014). On the contrary, there was no causal relationship between accelerometer-based PA (acceleration fraction >425 mg; OR = 0.9981, 95% CI = 0.9936-1.0026, P = 0.402) and AS. Furthermore, there was no significant relationship between self-reported vigorous PA and AS (OR = 1.0005, 95% CI = 0.9875-1.0136, P = 0.943), or even between self-reported moderate-to-vigorous PA and AS (OR = 1.0000, 95% CI, 0.9947-1.0052; P = 0.990).

Conclusions

The use of genetic approach in the present study revealed that total physical activity (TPA) has a protective relationship with AS risk. Furthermore, it was evident that vigorous PA or moderate-to-vigorous physical levels are not causally associated with AS. Therefore, the present study evidently supports the hypothesis that enhancing TPA rather than PA intensity is an effective prevention strategy for AS.

No causal effect of tea consumption on cardiovascular diseases: A two-sample Mendelian randomization study

Background

Numerous studies have been conducted to investigate the relationship between tea consumption and the risk of cardiovascular diseases (CVD); however, no conclusive results have been achieved. We conducted a Mendelian randomization (MR) study to elucidate the causal associations between tea consumption and several CVD outcomes, including coronary artery disease (CAD), myocardial infarction (MI), atrial fibrillation (AF), and heart failure (HF).

Methods

Independent single-nucleotide polymorphisms (SNPs) genome-wide significantly associated with tea consumption were used as instrumental variables (IVs). Summary statistics for CVD outcomes were obtained from the corresponding genetic consortia and the FinnGen consortium. The inverse-variance weighted (IVW) method was the primary analytical method, and MR estimates from different data sources were combined using fixed-effects meta-analysis. Supplementary MR analyses, including the weighted median, MR-Egger, and the MR pleiotropy residual sum and outlier methods, were conducted to evaluate the robustness of the results. Further MR analyses were repeated by including more genetic variants at a higher P-value threshold.

Results

We found that genetically predicted tea consumption was not causally associated with any CVD outcomes in the IVW method using data from large genetic consortia [CAD: odds ratio (OR) = 1.00, 95% confidence interval (CI), 0.91, 1.10, P = 0.997; MI: OR = 0.98, 95% CI, 0.90, 1.08, P = 0.751; AF: OR = 0.97, 95% CI, 0.92, 1.03, P = 0.350; HF: OR = 0.96, 95% CI, 0.88, 1.05, P = 0.401] or the FinnGen consortium (CAD: OR = 1.06, 95% CI, 0.96, 1.17, P = 0.225; MI: OR = 1.01, 95% CI, 0.89, 1.15, P = 0.882; AF: OR = 1.00, 95% CI, 0.88, 1.14, P = 0.994; HF: OR = 0.96, 95% CI, 0.88, 1.04, P = 0.362). The results were robust and consistent across meta-analysis, supplementary MR analyses, and analyses with more IVs included.

Conclusion

This MR study revealed no causal association between tea consumption and four CVD outcomes, suggesting that tea consumption may not be beneficial for the primary prevention of CVD.

Causal Associations of Obesity With Achilles Tendinopathy: A Two-Sample Mendelian Randomization Study

BACKGROUND

Achilles tendinopathy (AT) is associated with severe pain and is the cause of dysfunction and disability that are associated with significant reduction in social and economic benefits. Several potential risk factors have been proposed to be responsible for AT development; however, the results of observational epidemiological studies remain controversial, presumably because the designs of these studies are subject to residual confounding and reverse causality. Mendelian randomization (MR) can infer the causality between exposure and disease outcomes using genetic variants as instrumental variables, and identification of the causal risk factors for AT is beneficial for early intervention. Thus, we employed the MR strategy to evaluate the causal associations between previously reported risk factors (anthropometric parameters, lifestyle factors, blood biomarkers, and systemic diseases) and the risk of AT.

METHODS

Univariable MR was performed to screen for potential causal associations between the putative risk factors and AT. Bidirectional MR was used to infer reverse causality. Multivariable MR was conducted to investigate the body mass index (BMI)-independent causal effect of other obesity-related traits, such as the waist-hip ratio, on AT.

RESULTS

Univariable MR analyses with the inverse-variance weighted method indicated that the genetically predicted BMI was significantly associated with the risk of AT (P=2.0×10^-3), and the odds ratios (95% confidence intervals) is 1.44 (1.14-1.81) per 1-SD increase in BMI. For the other tested risk factors, no causality with AT was identified using any of the MR methods. Bidirectional MR suggested that AT was not causally associated with BMI, and multivariable MR indicated that other anthropometric parameters included in this study were not likely to causally associate with the risk of AT after adjusting for BMI.

CONCLUSIONS

The causal association between BMI and AT risk suggests that weight control is a promising strategy for preventing AT and alleviating the corresponding disease burden.