Mendelian randomization analysis identified causal Association of Childhood Obesity with adult major depressive disorder

Unravel the distinct effects of adiposity at different life stages on COVID-19 susceptibility and severity: A life-course Mendelian randomization study

Childhood obesity is widely recognized as a risk factor for numerous health conditions, particularly cardiovascular disease. However, it remains unclear whether childhood adiposity directly affects the risk of COVID-19 in later life. We aimed to investigate the causal effects of early life adiposity on COVID-19 susceptibility and severity. We used genetic instruments from large-scale genome-wide association studies to examine the relationships between birth weight, childhood and adulthood adiposity indicators (including body mass index [BMI], obesity, and body size), and COVID-19 outcomes. Univariable and multivariable Mendelian randomization (MR) analyses were used to obtain the causal estimates. Univariable MR analyses found that childhood BMI and obesity were positively associated with COVID-19 risk and severity in adulthood, however, the significant associations were attenuated to null after further adjusting for adulthood adiposity indicators in multivariable MR analyses. In contrast, our analysis revealed strong evidence of a genetically predicted effect of childhood obesity on COVID-19 hospitalization (OR 1.08, 95% CI: 1.01-1.15, p = 2.12E-2), which remained robust even after adjusting for adulthood obesity and potential lifestyle confounders. Our results highlight the importance of promoting healthy weight management throughout life to reduce the risk of COVID-19.

Mendelian randomization analysis separated the independent impact of childhood obesity and adult obesity on socioeconomic status, psychological status, and substance use

Background

Obesity is linked to a variety of psychosocial and behavioral outcomes but the causalities remain unclear yet. Determining the causalities and distinguishing between the separate effects of childhood and adult obesity is critical to develop more targeted strategies to prevent adverse outcomes.

Methods

With single nucleotide polymorphisms (SNPs) used as genetic variables, we employed univariable Mendelian randomization (UVMR) to explore the causalities between childhood and adult body mass index (BMI) and socioeconomic status, psychological status, and substance use. Genetic data for childhood and adult BMI came respectively from 47,541 children aged 10 years and 339,224 adult participants. The outcome data were obtained from corresponding consortia. The direct impact of childhood BMI and adult BMI was then examined using a multivariable MR (MVMR).

Results

UVMR found that higher childhood BMI was linked causally to lower household income (β = -0.06, 95 % CI = -0.08 ∼ -0.03, P = 4.86 × 10-5), decreased subjective well-being (β = -0.07, 95 % CI = -0.12 ∼ -0.03, P = 1.74 × 10-3), and an increased tendency of smoking regularly (OR = 1.12, 95 % CI = 1.04-1.20, P = 1.52 × 10-3). Similar results were observed in adult BMI. MVMR further revealed that after adjusting with adult BMI, childhood BMI remained an isolated impact on household income. The impacts of adult BMI on the outcomes were diminished when adjusting with childhood BMI.

Conclusion

The findings indicate the impacts of childhood obesity on subjective well-being and smoking initiation are a result of higher BMI sustaining into adulthood, whereas the effect on household income is attributed to a lasting impact of obesity in early life. The results would help facilitate more targeted strategies for obesity management to prevent adverse outcomes.

Evaluating the distinct effects of body mass index at childhood and adulthood on adult major psychiatric disorders

Children with high body mass index (BMI) are at heightened risk of developing health issues in adulthood, yet the causality between childhood BMI and adult psychiatric disorders remains unclear. Using a life course Mendelian randomization (MR) framework, we investigated the causal effects of childhood and adulthood BMI on adult psychiatric disorders, including Alzheimer's disease, anxiety, major depressive disorder, obsessive-compulsive disorder (OCD), and schizophrenia, using data from the Psychiatric Genomics Consortium and FinnGen study. Childhood BMI was significantly associated with an increased risk of schizophrenia, while adulthood BMI was associated with a decreased risk of OCD and schizophrenia. Multivariable MR analyses indicated a direct causal effect of childhood BMI on schizophrenia, independent of adulthood BMI and lifestyle factors. No evidence of causal associations was found between childhood BMI and other psychiatric outcomes. The sensitivity analyses yielded broadly consistent findings. These findings highlight the critical importance of early-life interventions to mitigate the long-term consequences of childhood adiposity.

Childhood obesity and adolescent follow-up depressive symptoms: exploring a moderated mediation model of body esteem and gender

Obesity is a well-recognized risk factor for adolescent depressive symptoms, but mediating mechanisms of this association have scarcely been studied. This study is unique in examining an indirect pathway of this link via body esteem (BE) prospectively from childhood (8-12 years) to adolescence (13-18 years). In addition, potential gender moderation was examined. This study utilized data from a case-control study comparing 100 children with and without obesity matched on important confounders (age, gender, and socioeconomic status). Our findings provide support for the mediating role of BE in the link between childhood weight status and adolescent depressive symptoms at a 5-year follow-up. This mediation effect did not differ between boys and girls. The findings suggest the relevance of specifically targeting children's BE in preventive intervention programs among children with obesity to prevent future mental health problems.

The potential and translational application of infant genetic research

In the current genomic revolution, the infancy life stage is the most neglected. Although clinical genetics recognizes the value of early identification in infancy of rare genetic causes of disorders and delay, common genetic variation is almost completely ignored in research on infant behavioral and neurodevelopmental traits. In this Perspective, we argue for a much-needed surge in research on common genetic variation influencing infant neurodevelopment and behavior, findings that would be relevant for all children. We now see convincing evidence from different research designs to suggest that developmental milestones, skills and behaviors of infants are heritable and thus are suitable candidates for gene-discovery research. We highlight the resources available to the field, including genotyped infant cohorts, and we outline, with recommendations, special considerations needed for infant data. Therefore, infant genetic research has the potential to impact basic science and to affect educational policy, public health and clinical practice.

Causal effects of childhood obesity on neuroticism and subjective well-being: A two-sample Mendelian randomization study

BACKGROUND

Childhood obesity is linked to both neuroticism and subjective wellbeing (SWB); however, the causal relations between them remain unclear.

METHODS

Two-sample Mendelian randomization (MR) analysis was applied to determine the causal effects of childhood BMI (n = 39,620) on neuroticism (n = 366,301) and SWB (n = 298,420) using summary statistics from large scale genome-wide association studies (GWASs). Inverse-variance weighting (IVW), weighted mode, weighted median, and MR-Egger approaches were used to estimate the causal effects. Sensitivity analyses including the Cochran's Q statistics, MR-Egger intercept test, MR-PRESSO global test, and the leave-one-out (LOO) analysis were used to assess potential heterogeneity and horizontal pleiotropy. Two-step MR mediation analysis was employed to explore the potential mediation effects of neuroticism on the causal relationship between childhood BMI and SWB.

RESULTS

Our study revealed that genetically predicted higher childhood BMI was causally associated with increased neuroticism (beta = 0.045, 95%CI = 0.013,0.077, p = 6.066e-03) and reduced SWB (beta = -0.059, 95%CI = -0.093,-0.024, p = 9.585e-04). Sensitivity analyses didn't detect any significant heterogeneity and horizontal pleiotropy (all p > 0.05). Additionally, the two-step MR mediation analysis indicated that the causal relationship between childhood BMI and SWB was partially mediated by neuroticism (proportion of mediation effects in total effects: 21.3 %, 95%CI: 5.4 % to 37.2, p = 0.0088).

CONCLUSION

Genetically proxy for higher childhood BMI was associated with increased neuroticism and reduced SWB. Further studies were warranted to investigate the underlying molecular mechanisms and potential use of weight management for improving personality and SWB.

The early life course-related traits with three psychiatric disorders: A two-sample Mendelian randomization study

Objectives

Several studies have indicated a potential association between early life course-related traits and neurological and psychiatric disorders in adulthood, but the causal link remains unclear.

Methods

Instrumental variables (IVs) that have been shown to be strongly associated with exposure were obtained from summary data of genome-wide association studies (GWASs). Four early life course-related traits [i.e., birthweight (BW), childhood body mass index (BMI), early body size, and age at first birth (AFB)] were used as exposure IVs to estimate their causal associations with three neurological and psychiatric diseases [i.e., Alzheimer's disease (AD), major depressive disorder (MDD), and attention-deficit hyperactivity disorder (ADHD)]. Four different statistical methods, i.e., inverse-variance weighting (IVW), MR-Egger (MRE), weighted median (WM), and weighted mode (Wm), were performed in our MR analysis. Sensitivity analysis was performed by using the leave-one-out method, and horizontal pleiotropy was assessed using the MR-PRESSO package.

Results

There was evidence suggesting that BW has a causal effect on AD (OR_MR-PRESSO = 1.05, p = 1.14E-03), but this association was not confirmed via multivariable Mendelian randomization (MVMR) (OR_MVMR = 0.97, 95% CI 0.92-1.02, p = 3.00E-01). A strong relationship was observed between childhood BMI and ADHD among both sexes; a 1-SD increase in BMI significantly predicted a 1.46-fold increase in the OR for ADHD (p = 9.13E-06). In addition, a similar relationship was found between early life body size and ADHD (OR_MR-PRESSO = 1.47, p = 9.62E-05), and this effect was mainly driven by male participants (OR_MR-PRESSO = 1.50, p = 1.28E-3). Earlier AFB could significantly predict a higher risk of MDD (OR_MR-PRESSO = 1.19, p = 1.96E-10) and ADHD (OR_MR-PRESSO = 1.45, p = 1.47E-15). No significant causal associations were observed between the remaining exposures and outcomes.

Conclusion

Our results reveal the adverse effects of childhood obesity and preterm birth on the risk of ADHD later in life. The results of MVMR also show that lower BW may have no direct relationship with AD after adjusting for BMI. Furthermore, AFB may predict a higher risk of MDD.

Body mass index and the risk of abdominal hernia: a Mendelian randomization study

PURPOSE

Abdominal hernia (AH) is one of the most common clinical diseases. A large number of observational studies have found that obesity is an important risk factor for AH. However, the causal relationship between obesity and AH cannot be determined because of the clinical studies on AH induced by obesity are relatively few and only have some small- or medium-scale observational studies. Observational studies have so many confounding factors and reverse causality due to their shortcomings. From an evidence-based medicine perspective, they are not sufficiently convincing. Therefore, there is still a lack of high-quality, evidence-based medical evidence supporting a causal relationship between obesity and AH. A causal relationship between obesity and AH is also almost impossible to confirm by randomized controlled trials (RCTs). Our study based on Mendelian randomization (MR) may provide a higher level of evidence-based medical support for the relationship between obesity and AH. Body mass index (BMI) is the most common measure used for defining obesity. Finally, we employed two-sample Mendelian randomization (TSMR) to explore the causal relationship between BMI and AH.

METHODS

AH-related single nucleotide polymorphisms (SNPs) data were obtained from the FinnGen Biobank (FB), and BMI-related single nucleotide polymorphisms (SNPs) data were obtained from the UK Biobank (UKB). Genetic loci are used as instrumental variables (IVs), methods such as inverse variance weighted (IVW) were used for two-sample Mendelian randomization analysis, and the odds ratio (OR) value was used to evaluate the causal relationship between BMI and AH.

RESULTS

The results of the horizontal pleiotropy test were calculated by Egger-intercept method: p = 0.34 > 0.05. The Cochran Q test of MR-Egger method and IVW method showed heterogeneity P = 0.03 < 0.05, so the IVW random effect model was used as the gold standard. We found a genetically determined 1-standard deviation (SD) increment of BMI causally increased a 66.0% risk of AH (N = 371 SNPs, OR = 1.66, 95% CI 1.46-1.89, p = 1.55E-14) based on the IVW random effect model which was almost consistent with the results of other seven methods.

CONCLUSIONS

Our MR found genetic evidence for BMI and AH. The risk of developing AH increases with the number of BMI. This finding provides further evidence that maintaining a healthy BMI can prevent the development of AH. In addition, clinicians may need to focus on the potential risk of AH on some high-BMI patients.