Project description:BackgroundEpidemiological studies have confirmed the relationship between personality trait neuroticism and physical health. However, the relationship between neuroticism and frailty remains unconfirmed. This study employed a bi-directional two-sample Mendelian randomization (MR) approach to investigate the causal relationship between neuroticism and frailty.MethodsThe neuroticism genome-wide association study (GWAS) data from the UK Biobank contained twelve neuroticism-related traits with 489,212 participants. The genetic frailty index data were extracted from the UK Biobank and Swedish TwinGene, involving 175,226 individuals. Independent genetic variants associated with neuroticism and frailty were selected as instrumental variables. Inverse variance weighted (IVW), MR-Egger, weighted median, weighted mode, and MR-PRESSO were mainly used for MR analysis.ResultsThe MR analysis showed a positive causal relationship between neuroticism and the risk of frailty (odds ratio (OR) = 1.627, 95% confidence interval (CI) = 1.538-1.722, P < 0.001). In the reverse direction, frailty had a causal effect on a higher risk of neuroticism (OR = 1.270, 95% CI = 1.173-1.375, P < 0.001). Steiger tests indicated that reverse causation did not bias the identified causal relationships.ConclusionsOur study provides genetic evidence suggesting a bi-directional causal relationship between frailty and neuroticism. In this bi-directional MR study, there were positive causal relationships between neuroticism-related phenotypes and frailty, and in the reverse direction, frailty was also positively correlated with neuroticism.
Project description:This study aimed to investigate the causal relationship between bone mineral density (BMD) and intervertebral disk degeneration (IVDD) using a two-sample bidirectional Mendelian randomization analysis. Summary-level data from the Genome-Wide Association Study (GWAS) were used. Instrumental variables (IVs) for IVDD were selected from the large-scale Genome-Wide Association Study (GWAS) (20,001 cases and 164,682 controls). Bone mineral density (BMD) at five different sites (heel (n = 426,824), total body (TB) (n = 56,284), forearm (FA) (n = 8143), femoral neck (FN) (n = 32,735), and lumbar spine (LS) (n = 28,498)) was used as a phenotype for OP. Bidirectional causality between IVDD and BMD was assessed using inverse variance weighting (IVW) and other methods. Related sensitivity analyses were performed. Myopia was also analyzed as a negative control result to ensure the validity of IVs. Heel bone mineral density (heel BMD), total body bone mineral density (TB-BMD), femoral neck bone mineral density (FN-BMD), and lumbar spine bone mineral density (LS-BMD) have a direct causal relationship on intervertebral disk degeneration (IVDD) [heel BMD-related analysis: beta = 0.06, p = 0.03; TB-BMD-related analysis: beta = 0.18, p = 8.72E-08; FN-BMD-related analysis: beta = 0.15, p = 4.89E-03; LS-BMD-related analysis: beta = 0.16, p = 1.43E-04]. There was no evidence of a significant causal effect of IVDD on BMD. In conclusion, our study found a significant positive causal effect of lower BMD on IVDD, and we identified significant causal effects of heel, TB-, FN-, and LS-BMD on IVDD, but there was no evidence of a significant causal effect of IVDD on BMD.
Project description:BackgroundOsteonecrosis (ON) is a debilitating orthopedic condition characterized by bone cell death due to impaired blood supply, leading to structural changes and disability. Osteoporosis (OP), a systemic skeletal disease, results in reduced bone density and quality, making bones fragile and prone to fractures. Although distinct, OP and ON share several risk factors such as corticosteroid use and smoking. This study aims to investigate the causal relationships between OP, bone mineral density (BMD), and ON using a bidirectional two-sample Mendelian randomization (MR) approach.MethodsThis study utilized genome-wide association study (GWAS) data for OP from the FinnGen database, and BMD data for the lumbar spine and femoral neck from the Genetic Factors for Osteoporosis (GEFOS) consortium. ON data were also obtained from the FinnGen database. All participants were of European descent. Genetic instruments were selected based on genome-wide significance, linkage disequilibrium, and strength (F-statistic). Bidirectional MR analysis was performed using inverse-variance weighted (IVW), MR-Egger regression, and weighted median methods to assess causality. Sensitivity analyses, including Cochran's Q test and MR-PRESSO, were conducted to evaluate heterogeneity and pleiotropy.ResultsMR analysis demonstrated a positive causal effect of OP on ON using the IVW method, with an odds ratio (OR) of 1.223 (95% CI: 1.026-1.459, P = 0.025). The weighted median method also confirmed this result with an OR (95% CI) 1.290 (1.021-1.630), P = 0.033. No significant causal effects were found between BMD (lumbar spine and femoral neck) and ON. Furthermore, ON did not exhibit a causal effect on OP or BMD. Sensitivity analyses confirmed the robustness of the results, showing no evidence of heterogeneity or pleiotropy.ConclusionThis study provides evidence of a unidirectional causal relationship between OP and ON, suggesting that individuals with a genetic predisposition to OP have an increased risk of developing ON. These findings highlight the importance of early OP detection and management to potentially reduce ON incidence. The lack of a significant causal relationship between BMD and ON indicates that factors other than bone density, such as vascular health, may play a crucial role in ON development. Future research should explore these mechanisms further to inform clinical interventions.
Project description:BackgroundPrevious 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.MethodsWe 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.ResultsOur 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.ConclusionThe 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.
Project description:BackgroundNumerous observational studies have suggested a correlation between sarcopenia and depression, but the nature of this relationship requires further investigation.MethodsThis study employed bidirectional Mendelian randomization to explore this connection. Data from genome-wide association studies were used, encompassing measures of sarcopenia and mental factors, including depression and emotional states. The initial analysis concentrated on the impact of depression on sarcopenia, and then it examined the reverse relationship. The same methodology was applied to emotional data for validation.ResultsThe results indicated a reciprocal causation between sarcopenia and depression, even when emotional state data were considered. Various emotions can impact sarcopenia, and in turn, sarcopenia can affect emotions, except subjective well-being. These findings highlight a cyclic deterioration between sarcopenia and depression, with a link to negative emotions and a partially ameliorative effect of subjective well-being on sarcopenia.ConclusionsIn summary, this study sheds light on the interplay between psychiatric factors and sarcopenia, offering insights into intervention and prevention strategies.
Project description:The purpose of this study was to verify whether there is a causal relationship between breast cancer and bone mineral density (BMD). Summary statistics for exposures and outcomes were obtained from corresponding genome-wide association studies. The bidirectional and multivariate mediated Mendelian randomization (MR) analyses were performed. In the bidirectional MR analysis, breast cancer might reduce the BMD of the heel (HE-BMD) (FDR = 1.51 × 10-4) as might its ER+ subtype (FDR = 1.51 × 10-4). From BMD to breast cancer, no significant association was found (FDR > 0.05). The mediating MR analysis showed that Higher free testosterone (FT) only mediated the causal relationship between breast cancer and HE-BMD by 2.9%; both ER+ type and FT were independent factors of HE-BMD (ER+: P = 0.021; FT: P = 6.88 × 10-6). Higher FT could increase the risk of breast cancer (FDR = 1.21 × 10-3) as could total testosterone (TT) (FDR = 5.81 × 10-3). Similarly, higher FT could increase the risk of ER+ subtype (FDR = 2.51 × 10-6) as could TT (FDR = 5.55 × 10-4). These results indicate that BMD is not a risk factor for breast cancer but breast cancer and its ER+ subtype are risk factors for BMD loss. Furthermore, higher FT and TT levels are associated with both an increased incidence of breast cancer and increased bone density.
Project description:IntroductionThe association of air pollution with bone mineral density (BMD) has attracted increasing attention. However, establishing a causal relationship remains uncertain.MethodsWe conducted a Mendelian randomization (MR) study employing PM2.5, PM2.5-10, PM10, nitrogen dioxide, and nitrogen oxides as exposures and BMD as the outcome to explore the causality between air pollution and the occurrence of decreased BMD.ResultsBy employing the IVW method, we identified a negative causality between air pollution (PM2.5, PM10, and nitrogen oxides) and BMD.ConclusionsOur findings demonstrate that PM2.5, PM10 and nitrogen oxides exposure may contribute to decreased BMD.
Project description:BackgroundWhile growing evidence suggests a relationship between migraine and cardiovascular disease, the genetic evidence for a causal relationship between migraine and cardiovascular disease is still scarce. Investigating the causal association between migraine and cardiovascular disease is vital.MethodsWe carried out a bidirectional Mendelian randomization (MR) study including discovery samples and replication samples using publicly available genome-wide association study (GWAS) summary datasets and stringent screening instrumental variables. Four different MR techniques-Inverse variance weighted (IVW), MR ‒Egger, weighted median, and weighted mode-as well as various sensitivity analyses-Cochran's Q, IVW radial, leave-one-out (LOO), and MR-PRESSO-were utilized to investigate the causal relationship between cardiovascular disease and migraine.ResultsThe protective causal effects of genetically predicted migraine on coronary artery disease (OR, 0.881; 95% CI 0.790-0.982; p = 0.023) and ischemic stroke (OR, 0.912; 95% CI 0.854-0.974; p = 0.006) were detected in forward MR analysis but not in any other cardiovascular disease. Consistently, we also discovered protective causal effects of coronary atherosclerosis (OR, 0.865; 95% CI 0.797-0.940; p = 0.001) and myocardial infarction (OR, 0.798; 95% CI 0.668-0.952; p = 0.012) on migraine in reverse MR analysis.ConclusionWe found a potential protective effect of migraine on coronary artery disease and ischemic stroke and a potential protective effect of coronary atherosclerosis and myocardial infarction on migraine. We emphasised epidemiological and genetic differences and the need for long-term safety monitoring of migraine medications and future research to improve cardiovascular outcomes in migraine patients.
Project description:Background and purpose Observational studies have shown that sarcopenia and diabetic nephropathy (DN), are closely related; however, the causal relationship is unclear. This study aims to address this issue using a bidirectional Mendelian randomization (MR) study. Methodology We data from genome-wide association studies including appendicular lean mass (n = 244,730), grip strength (right: n = 461,089, left: n = 461026), walking speed (n = 459,915), and DN (3283 cases and 181,704 controls) to conduct a bidirectional MR study. First, we conducted a Forward MR analysis to evaluate the causality of sarcopenia on the risk of DN from the genetic perspective with appendicular lean mass, grip strength, and walking speed as exposure and DN as the outcome. Then, DN as the exposure, we performed a Reverse MR analysis to determine whether DN impacted the appendicular lean mass, grip strength, and walking speed of the appendices. Finally, a series of sensitivity studies, such as heterogeneity tests, pleiotropy evaluations, and Leave-one-out analyses, were conducted to assess the MR analysis’s accuracy further. Results According to a forward MR analysis, a genetically predicted decrease in appendicular lean mass is associated with an increased risk of developing DN risk (inverse variance weighting[IVW]: odd ratio [OR] = 0.863, 95% confidence interval [CI] 0.767-0.971; P = 0.014). According to reverse MR results, grip strength decreased as DN progressed (IVW: right β = 0.003, 95% CI: - 0.021 to - 0.009, P = 5.116e-06; left β = 0.003, 95% CI: - 0.024 to - 0.012, P = 7.035e-09). However, the results of the other MR analyses were not statistically different. Conclusion Notably, our findings suggest that the causal relationship between sarcopenia and DN cannot be generalized. According to analysis of the individual characteristic factors of sarcopenia, reducing in appendicular lean mass increases the risk of developing DN and DN is linked to reduced grip strength. But overall, there is no causal relationship between sarcopenia and DN, because the diagnosis of sarcopenia cannot be determined by one of these factors alone.
Project description:BackgroundObservational studies have shown a link between autoimmune diseases and schizophrenia, with conflicting conclusions. Due to the existence of confounding factors, the causal link between autoimmune diseases and schizophrenia is still unknown.MethodWe conducted a comprehensive Mendelian randomization (MR) analysis of schizophrenia and ten common autoimmune diseases in individuals of European descent using genome-wide association studies (GWASs). To evaluate the relationships between autoimmune diseases and schizophrenia, inverse variance weighted, MR-RAPS, Bayesian weighted MR, constrained maximum likelihood, debiased IVW, MR-Egger, and weighted median were utilized. Several sensitivity analyses were performed to ensure the reliability of the study's results.ResultsOur findings reveal that genetically predicted ankylosing spondylitis is related to an increased risk of schizophrenia, whereas celiac disease, type 1 diabetes, and systemic lupus erythematosus are associated with a lower risk of schizophrenia. In the reverse MR analysis, our study indicated that genetically predicted schizophrenia is linked to higher risks of ankylosing spondylitis, Crohn's disease, ulcerative colitis, inflammatory bowel disease, and psoriasis. Neither multiple sclerosis nor rheumatoid arthritis have been linked to schizophrenia, and vice versa.ConclusionDespite contradicting some other observational reports, this study showed support for a causal link between autoimmune diseases and schizophrenia. To gain a better understanding of the mechanisms underlying the development of immune-mediated schizophrenia, additional research is required to identify potential mechanisms identified in observational studies.