Assessing the causal role of adiposity on disordered eating in childhood, adolescence, and adulthood: a Mendelian randomization analysis

Methodological approaches, challenges, and opportunities in the application of Mendelian randomisation to lifecourse epidemiology: A systematic literature review

Diseases diagnosed in adulthood may have antecedents throughout (including prenatal) life. Gaining a better understanding of how exposures at different stages in the lifecourse influence health outcomes is key to elucidating the potential benefits of disease prevention strategies. Mendelian randomisation (MR) is increasingly used to estimate causal effects of exposures across the lifecourse on later life outcomes. This systematic literature review explores MR methods used to perform lifecourse investigations and reviews previous work that has utilised MR to elucidate the effects of factors acting at different stages of the lifecourse. We conducted searches in PubMed, Embase, Medline and MedRXiv databases. Thirteen methodological studies were identified. Four studies focused on the impact of time-varying exposures in the interpretation of "standard" MR techniques, five presented methods for repeat measures of the same exposure, and four described methodological approaches to handling multigenerational exposures. A further 127 studies presented the results of an applied research question. Over half of these estimated effects in a single generation and were largely confined to the exploration of questions regarding body composition. The remaining mostly estimated maternal effects. There is a growing body of research focused on the development and application of MR methods to address lifecourse research questions. The underlying assumptions require careful consideration and the interpretation of results rely on select conditions. Whilst we do not advocate for a particular strategy, we encourage practitioners to make informed decisions on how to approach a research question in this field with a solid understanding of the limitations present and how these may be affected by the research question, modelling approach, instrument selection, and data availability.

Mendelian Randomization Analysis Identifies Inverse Causal Relationship between External Eating and Metabolic Phenotypes

Disordered eating contributes to weight gain, obesity, and type 2 diabetes (T2D), but the precise mechanisms underlying the development of different eating patterns and connecting them to specific metabolic phenotypes remain unclear. We aimed to identify genetic variants linked to eating behaviour and investigate its causal relationships with metabolic traits using Mendelian randomization (MR). We tested associations between 30 genetic variants and eating patterns in individuals with T2D from the Volga-Ural region and investigated causal relationships between variants associated with eating patterns and various metabolic and anthropometric traits using data from the Volga-Ural population and large international consortia. We detected associations between HTR1D and CDKAL1 and external eating; between HTR2A and emotional eating; between HTR2A, NPY2R, HTR1F, HTR3A, HTR2C, CXCR2, and T2D. Further analyses in a separate group revealed significant associations between metabolic syndrome (MetS) and the loci in CRP, ADCY3, GHRL, CDKAL1, BDNF, CHRM4, CHRM1, HTR3A, and AKT1 genes. MR results demonstrated an inverse causal relationship between external eating and glycated haemoglobin levels in the Volga-Ural sample. External eating influenced anthropometric traits such as body mass index, height, hip circumference, waist circumference, and weight in GWAS cohorts. Our findings suggest that eating patterns impact both anthropometric and metabolic traits.

Triangulating causality between childhood obesity and neurobehavior: Behavioral genetic and longitudinal evidence

Childhood obesity is a serious health concern that is not yet fully understood. Previous research has linked obesity with neurobehavioral factors such as behavior, cognition, and brain morphology. The causal directions of these relationships remain mostly untested. We filled this gap by using the Adolescent Brain Cognitive Development study cohort comprising 11,875 children aged 9-10. First, correlations between the age- and sex-specific 95th BMI percentile (%BMIp95) and neurobehavioral measures were cross-sectionally analyzed. Effects were then aggregated by neurobehavioral domain for causal analyses. Behavioral genetic Direction of Causation modeling was used to test the direction of each relationship. Findings were validated by longitudinal cross-lagged panel modeling. %BMIp95 correlated with impulsivity, motivation, psychopathology, eating behavior, and cognitive tests (executive functioning, language, memory, perception, working memory). Greater %BMIp95 was also associated with reduced cortical thickness in frontal and temporal brain areas but with increased thickness in parietal and occipital areas. Similar although weaker patterns emerged for cortical surface area and volume. Behavioral genetic modeling suggested causal effects of %BMIp95 on eating behavior (β = 0.26), cognition (β = 0.05), cortical thickness (β = 0.15), and cortical surface area (β = 0.07). Personality/psychopathology (β = 0.09) and eating behavior (β = 0.16) appeared to influence %BMIp95. Longitudinal evidence broadly supported these findings. Results regarding cortical volume were inconsistent. Results supported causal effects of obesity on brain functioning and morphology. The present study highlights the importance of physical health for brain development and may inform interventions aimed at preventing or reducing pediatric obesity. RESEARCH HIGHLIGHTS: A continuous measure related to obesity, %BMIp95, has correlations with various measures of brain functioning and structure Behavioral genetic and longitudinal modeling suggest causal links from personality, psychopathology, and eating behavior to %BMIp95 Results also indicate directional links from %BMIp95 to eating behavior, cognition, cortical thickness, and cortical surface area Obesity may play a role for healthy brain development during childhood.

Childhood body mass index and the subsequent risk of anorexia nervosa and bulimia nervosa among women: A large Danish population-based study

OBJECTIVE

Evidence linking childhood body mass index (BMI) with subsequent eating disorders is equivocal. Potential explanations include different study populations and size, and that anorexia nervosa (AN) and bulimia nervosa (BN) should be studied separately. We examined whether birthweight and childhood BMI were associated with subsequent risk of AN and BN in girls.

METHOD

We included 68,793 girls from the Copenhagen School Health Records Register born between 1960 and 1996 with information on birthweight and measured weights and heights obtained from school health examinations at ages 6-15 years. Diagnoses of AN and BN were retrieved from Danish nationwide patient registers. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

We identified 355 cases of AN (median age: 19.0) and 273 cases of BN (median age: 21.8). Higher childhood BMI was linearly associated with decreasing risk of AN and increasing risk of BN at all childhood ages. At age 6, the HR for AN was 0.85 (95% CI: 0.74-0.97) per BMI z-score and the HR for BN was 1.78 (95% CI: 1.50-2.11) per BMI z-score. Birthweight >3.75 kg was associated with increased risk of BN compared to a birthweight of 3.26-3.75 kg.

CONCLUSION

Higher BMI in girls at ages 6-15 years was associated with decreasing risk of AN and increasing risk of BN. Premorbid BMI could be relevant for the etiology of AN and BN, and in identifying high risk individuals.

PUBLIC SIGNIFICANCE

Eating disorders are associated with elevated mortality, especially AN. Using a cohort of Copenhagen school children, we linked information on BMI at ages 6-15 years for 68,793 girls with nationwide patient registers. Low childhood BMI was associated with increased risk of AN, whereas high childhood BMI was associated with increased risk of BN. These findings may assist clinicians in identifying individuals at high-risk of these diseases.

Patterns of Eating Behavior among 13-Year-Old Adolescents and Associated Factors: Findings from the Generation XXI Birth Cohort

Eating behavior adopted during adolescence may persist into adulthood. The aims of this study were to identify eating behavior patterns among Portuguese adolescents and to explore whether groups differ in terms of early life and family characteristics, severity of depressive symptoms, and body mass index (BMI) z-score. Participants were 3601 13-year-olds enrolled in the birth cohort Generation XXI. Eating behavior was assessed using the self-reported Adult Eating Behavior Questionnaire (AEBQ), validated in this sample. The severity of depressive symptoms was measured through the Beck Depression Inventory (BDI-II), and data on sociodemographic and anthropometrics were collected at birth and 13-years-old. Latent class analysis was conducted, and associations were estimated using multinomial logistic regression models. Five patterns of individuals were identified: "Picky eating", "Disinterest towards food", "Food neophilia", "Emotional eating", and "Food attractiveness". The adolescents' sex, maternal education, BMI z-score, and severity of depressive symptoms were significantly associated with the identified patterns. In particular, adolescents with a higher BMI z-score were more likely in "Food neophilia" while individuals with more severe depressive symptoms were in the "Picky eating", "Emotional eating", and "Food attractiveness" patterns. These findings suggest a starting point for the development and planning of targeted public health interventions.

Subclinical binge eating symptoms in early adolescence and its preceding and concurrent factors: a population-based study

OBJECTIVE

Binge eating, loss of control eating and overeating often develop during late childhood or early adolescence. Understanding the presentation of binge eating as early as symptoms manifest and its preceding and concurrent factors is essential to hamper the development of eating disorders. This study examined the prevalence, concurrent and preceding factors (e.g. compensatory behaviors, emotional and behavioral problems) of subclinical binge eating symptoms in early adolescence.

METHODS

Data from the population-based Generation R Study were used (n = 3595). At 10 years and 14 years, preceding and concurrent factors including eating behaviors, body dissatisfaction, emotional and behavioral problems and body composition were assessed. At 14 years, 3595 adolescents self-reported on binge eating symptoms in the past 3 months and were categorized into four groups: no symptoms (n = 3143, 87.4%), overeating only (n = 121, 3.4%), loss of control (LOC) eating only (n = 252, 7.0%) or binge eating (i.e. both, n = 79, 2.2%).

RESULTS

In total, 452 (12.6%) young adolescents reported subclinical binge eating symptoms. Those who reported LOC eating and binge eating showed most compensatory behaviors (e.g. hide or throw away food, skipping meals). Concurrent emotional and behavioral problems, body dissatisfaction, more emotional-, restrained- and uncontrolled eating, and a higher BMI were associated with subclinical binge eating symptoms. Preceding self-reported emotional and behavioral problems, body dissatisfaction, more restrained eating and higher BMI (both fat mass and fat-free mass) at 10 years were associated with LOC eating and binge eating, but not with overeating.

DISCUSSION

Among young adolescents, subclinical binge eating symptoms were common. Considering the high prevalence of LOC eating, and the overlapping preceding and concurrent factors of LOC eating and binge eating compared to overeating, LOC eating seems to be a key symptom of binge eating in early adolescence.

Genetics and neurobiology of eating disorders

Eating disorders (anorexia nervosa, bulimia nervosa and binge-eating disorder) are a heterogeneous class of complex illnesses marked by weight and appetite dysregulation coupled with distinctive behavioral and psychological features. Our understanding of their genetics and neurobiology is evolving thanks to global cooperation on genome-wide association studies, neuroimaging, and animal models. Until now, however, these approaches have advanced the field in parallel, with inadequate cross-talk. This review covers overlapping advances in these key domains and encourages greater integration of hypotheses and findings to create a more unified science of eating disorders. We highlight ongoing and future work designed to identify implicated biological pathways that will inform staging models based on biology as well as targeted prevention and tailored intervention, and will galvanize interest in the development of pharmacologic agents that target the core biology of the illnesses, for which we currently have few effective pharmacotherapeutics.

Novel insights into the consequences of obesity: a phenotype-wide Mendelian randomization study

Obesity is thought to significantly impact the quality of life. In this study, we sought to evaluate the health consequences of obesity on the risk of a broad spectrum of human diseases. The causal effects of exposing to obesity on health outcomes were inferred using Mendelian randomization (MR) analyses using a fixed effects inverse-variance weighted model. The instrumental variables were SNPs associated with obesity as measured by body mass index (BMI) reported by GIANT consortium. The spectrum of outcome consisted of the phenotypes from published GWAS and the UK Biobank. The MR-Egger intercept test was applied to estimate horizontal pleiotropic effects, along with Cochran's Q test to assess heterogeneity among the causal effects of instrumental variables. Our MR results confirmed many putative disease risks due to obesity, such as diabetes, dyslipidemia, sleep disorder, gout, smoking behaviors, arthritis, myocardial infarction, and diabetes-related eye disease. The novel findings indicated that elevated red blood cell count was inferred as a mediator of BMI-induced type 2 diabetes in our bidirectional MR analysis. Intriguingly, the effects that higher BMI could decrease the risk of both skin and prostate cancers, reduce calorie intake, and increase the portion size warrant further studies. Our results shed light on a novel mechanism of the disease-causing roles of obesity.

Associations between Children's Genetic Susceptibility to Obesity, Infant's Appetite and Parental Feeding Practices in Toddlerhood

Previous findings suggest that parental feeding practices may adapt to children's eating behavior and sex, but few studies assessed these associations in toddlerhood. We aimed to study the associations between infant's appetite or children's genetic susceptibility to obesity and parental feeding practices. We assessed infant's appetite (three-category indicator: low, normal or high appetite, labelled 4-to-24-month appetite) and calculated a combined obesity risk-allele score (genetic risk score of body mass index (BMI-GRS)) in a longitudinal study of respectively 1358 and 932 children from the EDEN cohort. Parental feeding practices were assessed at 2-year-follow-up by the CFPQ. Three of the five tested scores were used as continuous variables; others were considered as binary variables, according to the median. Associations between infant's appetite or child's BMI-GRS and parental feeding practices were assessed by linear and logistic regression models, stratified on child's sex if interactions were significant. 4-to-24-month appetite was positively associated with restrictive feeding practices among boys and girls. Among boys, high compared to normal 4-to-24-month appetite was associated with higher use of food to regulate child's emotions (OR [95% CI] = 2.24 [1.36; 3.68]). Child's BMI-GRS was not related to parental feeding practices. Parental feeding practices may adapt to parental perception of infant's appetite and child's sex.

Separating the genetics of childhood and adult obesity: a validation study of genetic scores for body mass index in adolescence and adulthood in the HUNT Study

From a life-course perspective, genetic and environmental factors driving childhood obesity may have a lasting influence on health later in life. However, how obesity trajectories vary throughout the life-course remains unknown. Recently, Richardson et al. created powerful early life and adult gene scores for body mass index (BMI) in a comprehensive attempt to separate childhood and adult obesity. The childhood score was derived using questionnaire-based data administered to adults aged 40-69 regarding their relative body size at age 10, making it prone to recall and misclassification bias. We therefore attempted to validate the childhood and adult scores using measured BMI data in adolescence and adulthood among 66 963 individuals from the HUNT Study in Norway from 1963 to 2019. The predictive performance of the childhood score was better in adolescence and early adulthood, whereas the predictive performance of the adult score was better in adulthood. In the age group 12-15.9 years, the variance explained by the childhood polygenic risk score (PRS) was 6.7% versus 2.4% for the adult PRS. In the age group 24-29.9 years, the variance explained by the adult PRS was 3.9% versus 3.6% for the childhood PRS. Our findings support that genetic factors driving BMI differ at young age and in adulthood. Within the framework of multivariable Mendelian randomization, the validated childhood gene score can now be used to determine the consequence of childhood obesity on later disease.

Longitudinal associations between circulating interleukin-6 and C-reactive protein in childhood, and eating disorders and disordered eating in adolescence

OBJECTIVE

Few studies have explored the association between inflammation and eating disorders and none used a longitudinal design. We investigated the association between serum-levels of interleukin 6 (IL-6) and C-reactive protein (CRP) measured in childhood and eating disorders and related behaviours and cognitions in adolescence in a large general population sample.

METHODS

We used data from the Avon Longitudinal Study of Parents and Children (ALSPAC). Our exposures were thirds of IL6 and CRP derived from serum measurements taken at age nine years, and outcomes were eating disorder diagnoses and self-reported disordered eating behaviours at ages 14, 16, and 18 years. We used univariable and multivariable multilevel logistic regression models adjusting for a number of potential confounders, including sex, fat mass, and pre-existing mental health difficulties.

RESULTS

Our sample included 3480 children. Those in the top third of CRP had lower odds of binge eating (odds ratio(OR):0.62, 95% confidence interval (CI):0.39,1.00,p "equals" 0.05) and fasting (OR:0.63, 95% CI:0.38,1.07,p "equals" 0.09) after adjustment for confounders. We also observed weak associations of comparable magnitude for purging, anorexia nervosa, and bulimia nervosa. We did not find any associations between levels of IL6 and any of the outcomes under study.

CONCLUSIONS

There was little evidence of an association between CRP and IL-6 and adolescent eating disorder outcomes. The inverse association observed between CRP and binge eating was unexpected, so caution is needed when interpreting it. One possible explanation is that higher CRP levels could have a protective role for disordered eating by affecting appetitive traits.

Prospective Pathways to Depressive Symptoms and Disordered Eating in Adolescence: A 7-Year Longitudinal Cohort Study

Eating pathology and depressive symptoms increase during adolescence, yet predictive pathways remain predominantly unexplored, despite their implications for prevention. The present study aimed to identify shared risk factors for eating pathology and depressive symptoms by evaluating an adapted Dual-Pathway Model of disordered eating, which postulated that higher BMI would predict disordered eating and depressive symptoms via pathways between body dissatisfaction, later BMI, depressive symptoms, and visible indicators of puberty (breast development for girls, height for boys). The participants were 8915 children (49% girls) from the Avon Longitudinal Study of Parents and Children, a population-based cohort study of British children, who were assessed at different intervals between the age of 7 to 14 years. Path analyses revealed that, for girls, childhood BMI exerted indirect effects on disordered eating via body dissatisfaction, depressive symptoms, and more advanced breast development, with indirect pathways identified to depressive symptoms via earlier depressive symptoms and more advanced breast development. For boys, childhood BMI had indirect effects on disordered eating via later BMI and body dissatisfaction, while only earlier depressive symptoms were found to have an independent and direct effect on adolescent depressive symptoms. This study reveals shared and independent risk factors for eating pathology and depressive symptoms in adolescence and suggests targets for preventative interventions, including higher BMI, body dissatisfaction, and depressive symptoms, in addition to advanced breast development, for girls.

Polygenic Score for Body Mass Index Is Associated with Disordered Eating in a General Population Cohort

Background: Disordered eating (DE) is common and is associated with body mass index (BMI). We investigated whether genetic variants for BMI were associated with DE. Methods: BMI polygenic scores (PGS) were calculated for participants of the Avon Longitudinal Study of Parents and Children (ALSPAC; N = 8654) and their association with DE tested. Data on DE behaviors (e.g., binge eating and compensatory behaviors) were collected at ages 14, 16, 18 years, and DE cognitions (e.g., body dissatisfaction) at 14 years. Mediation analyses determined whether BMI mediated the association between the BMI-PGS and DE. Results: The BMI-PGS was positively associated with fasting (OR = 1.42, 95% CI = 1.25, 1.61), binge eating (OR = 1.28, 95% CI = 1.12, 1.46), purging (OR = 1.20, 95% CI = 1.02, 1.42), body dissatisfaction (Beta = 0.99, 95% CI = 0.77, 1.22), restrained eating (Beta = 0.14, 95% CI = 0.10, 1.17), emotional eating (Beta = 0.21, 95% CI = 0.052, 0.38), and negatively associated with thin ideal internalization (Beta = −0.15, 95% CI = −0.23, −0.07) and external eating (Beta = −0.19, 95% CI = −0.30, −0.09). These associations were mainly mediated by BMI. Conclusions: Genetic variants associated with BMI are also associated with DE. This association was mediated through BMI suggesting that weight potentially sits on the pathway from genetic liability to DE.

Developmental Premorbid Body Mass Index Trajectories of Adolescents With Eating Disorders in a Longitudinal Population Cohort

OBJECTIVE

To examine whether childhood body mass index (BMI) trajectories are prospectively associated with later eating disorder (ED) diagnoses.

METHOD

Using a subsample from the Avon Longitudinal Study of Parents and Children (N = 1,502), random-coefficient growth models were used to compare premorbid BMI trajectories of individuals who later developed anorexia nervosa (n = 243), bulimia nervosa (n = 69), binge-eating disorder (n = 114), and purging disorder (n = 133) and a control group without EDs or ED symptoms (n = 966). BMI was tracked longitudinally from birth to 12.5 years of age and EDs were assessed at 14, 16, and 18 years of age.

RESULTS

Distinct developmental trajectories emerged for EDs at a young age. The average growth trajectory for individuals with later anorexia nervosa veered significantly below that of the control group before 4 years of age for girls and 2 years for boys. BMI trajectories were higher than the control trajectory for all other ED groups. Specifically, the mean bulimia nervosa trajectory veered significantly above that of controls at 2 years for girls, but boys with later bulimia nervosa did not exhibit higher BMIs. The mean binge-eating disorder and purging disorder trajectories significantly diverged from the control trajectory at no older than 6 years for girls and boys.

CONCLUSION

Premorbid metabolic factors and weight could be relevant to the etiology of ED. In anorexia nervosa, premorbid low weight could represent a key biological risk factor or early manifestation of an emerging disease process. Observing children whose BMI trajectories persistently and significantly deviate from age norms for signs and symptoms of ED could assist the identification of high-risk individuals.

Weight suppression and its relation to eating disorder and weight outcomes: a narrative review

Weight suppression (WS) refers to the discrepancy between highest adult weight and current weight, and has been examined as a key construct related to both: eating pathology and weight management. However, despite increasing interest in WS, findings regarding the clinical implications of WS are often conflicting. For instance, WS has been associated with both adaptive and maladaptive outcomes across various populations. Moreover, results regarding the predictive utility of WS within clinical samples have been inconsistent. The current paper aims to provide a narrative review of existing investigation related to WS, highlight gaps in the field's understanding of this construct, and outline recommendations for future study.

Eating behavior and body composition across childhood: a prospective cohort study

Background

Although many cross-sectional studies reported that children with overweight or obesity show more food approaching and less food avoidant eating behaviors, there is a lack of replication in longitudinal studies. Therefore, the question remains whether healthcare professionals should target eating behaviors in childhood obesity interventions and prevention. We aimed to examine the longitudinal and possible bi-directional associations between eating behavior and body composition across childhood.

Methods

Data was included from 3331 children participating in the Generation R Study. At 4 and 10 years, mothers reported on the Child Eating Behavior Questionnaire including the subscales Food Responsiveness, Enjoyment of Food, Emotional Overeating and Satiety Responsiveness, and children’s BMI was measured. Body composition, consisting of Fat Mass Index and Fat Free Mass Index was measured at 6 and 10 years with Dual-energy-X-ray-Absorptiometry scans.

Results

Cross-lagged models including both directions of the BMI – eating behavior association showed that a higher BMI at the age of 4 years predicted more food responsiveness and enjoyment of food and less satiety responsiveness at 10 years (e.g. satiety responsiveness:β = − 0.10, 95% CI = − 0.14, − 0.07), but no associations were found in the opposite direction. For emotional overeating, however, a bi-directional association was found with BMI predicting more emotional eating and vice versa. Multivariable linear regression analyses showed that associations were stronger for Fat Mass Index than for Fat Free Mass Index.

Conclusions

Results showed that a higher BMI, and particularly higher fat mass, at pre-school age predicted more food approaching and less food avoidant eating behaviors at the age of 10 years, rather than the hypothesized reverse direction. This suggests that increased adiposity in early childhood might upregulate appetite and related eating behaviors.

Electronic supplementary material

The online version of this article (10.1186/s12966-018-0725-x) contains supplementary material, which is available to authorized users.

Associations of parents' self, child, and other "fat talk" with child eating behaviors and weight

OBJECTIVE

Fat talk, negative communication about weight, is common in the media, peer groups, and families. Little is known about parental fat talk directed at oneself or others. This study examined associations between different forms of parental fat talk and child disordered eating behaviors and weight, and differences by child sex and age.

METHOD

Parents of preadolescents or adolescents (n = 581) reported fat talk about themselves (self-fat talk), others (obesity-fat talk), and their child (child-fat talk).

RESULTS

76.0% of parents reported regular self-fat talk in front of children, 51.5% reported obesity-fat talk, and 43.6% reported child-fat talk. Fat talk did not differ significantly between parents of preadolescents and adolescents but was more common with sons than daughters. Of the three forms of fat talk, only child-fat talk was associated with all child eating and weight variables (binge eating, overeating, secretive eating, and overweight/obesity); associations were strongest for adolescent girls. Child sex was associated with secretive eating and overweight/obesity.

CONCLUSIONS

Parents reported using different forms of fat talk frequently. Parent self- and obesity-fat talk were reported more frequently, but child-fat talk was the most strongly associated with children's eating and weight. Because of associations with disordered eating behaviors, intervening to reduce fat talk might contribute to improving pediatric disordered eating and weight-related interventions.

The genetics of adiposity

Genome-wide discovery efforts have identified more than 500 genetic loci associated with adiposity traits. The vast majority of these loci were found through large-scale meta-analyses for body mass index (BMI) and waist-to-hip ratio (WHR), and in European ancestry populations. However, alternative approaches, focusing on non-European ancestry populations, more refined adiposity measures, and low-frequency (minor allele frequency (MAF)<5%) coding variants, identified additional novel loci that had not been identified before. Loci associated with overall obesity implicate pathways that act in the brain, whereas loci associated with fat distribution point to pathways involved in adipocyte biology. Pinpointing the causal gene within each locus remains challenging, but is a critical step towards translation of genome-wide association study (GWAS) loci into new biology. Ultimately, new genes may provide pharmacological targets for the development of weight loss drugs.

Assessing the Associations of Blood Metabolites With Osteoporosis: A Mendelian Randomization Study

Context

Osteoporosis is a metabolic bone disease. The effect of blood metabolites on the development of osteoporosis remains elusive.

Objective

To explore the relationship between blood metabolites and osteoporosis.

Design and Methods

We used 2286 unrelated white subjects for the discovery samples and 3143 unrelated white subjects from the Framingham Heart Study (FHS) for the replication samples. The bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry. Genome-wide single nucleotide polymorphism (SNP) genotyping was performed using Affymetrix Human SNP Array 6.0 (for discovery samples) and Affymetrix SNP 500K and 50K array (for FHS replication samples). The SNP sets significantly associated with blood metabolites were obtained from a reported whole-genome sequencing study. For each subject, the genetic risk score of the metabolite was calculated from the genotype data of the metabolite-associated SNP sets. Pearson correlation analysis was conducted to evaluate the potential effect of blood metabolites on the variations in bone phenotypes; 10,000 permutations were conducted to calculate the empirical P value and false discovery rate.

Results

We analyzed 481 blood metabolites. We identified multiple blood metabolites associated with hip BMD, such as 1,5-anhydroglucitol (Pdiscovery < 0.0001; Preplication = 0.0361), inosine (Pdiscovery = 0.0018; Preplication = 0.0256), theophylline (Pdiscovery = 0.0048; Preplication = 0.0433, gamma-glutamyl methionine (Pdiscovery = 0.0047; Preplication = 0.0471), 1-linoleoyl-2-arachidonoyl-GPC (18:2/20:4n6; Pdiscovery = 0.0018; Preplication = 0.0390), and X-12127 (Pdiscovery = 0.0002; Preplication = 0.0249).

Conclusions

Our results suggest a modest effect of blood metabolites on the variations of BMD and identified several candidate blood metabolites for osteoporosis.

Factors Associated with Binge Eating Behavior among Malaysian Adolescents

Although there are numerous studies on binge eating behavior in the Western countries, studies on this behavior in Malaysia are still limited. Therefore, this cross-sectional study aimed to determine the risk factors associated with binge eating behavior among adolescents in Malaysia. The study included 356 adolescents (42.7% males and 57.3% females), aged 13 to 16 years. They completed a self-administered questionnaire on demographic and socioeconomic backgrounds, frequency of family meals, family meal environments, family cohesion, perception of body size, self-esteem, depressive symptoms, perfectionistic self-presentation, and binge eating behavior. Furthermore, their weight, height, and waist circumference were measured. It was found that 14.0% of the participants engaged in binge eating behavior (15.2% in females and 12.5% in males). Additionally, it was identified that high levels of depressive symptoms, high levels of body dissatisfaction, poor family cohesion, and low self-esteem were significantly contributed to binge eating behavior after controlling for sex (adjusted R² = 0.165, F = 15.056, p < 0.001). The findings may suggest that improving the relationships between family members, along with eliminating adolescents’ negative emotions could help in the prevention of binge eating behavior among adolescents. The identified modifiable risk factors should be incorporated into binge eating preventive programs to increase the effectiveness of the programs.