Differences in genetic and environmental influences on body weight and shape concerns across pubertal development in females

Anorexia nervosa polygenic risk, beyond diagnoses: relationship with adolescent disordered eating and behaviors in an Australian female twin population

BACKGROUND

It is well established that there is a substantial genetic component to eating disorders (EDs). Polygenic risk scores (PRSs) can be used to quantify cumulative genetic risk for a trait at an individual level. Recent studies suggest PRSs for anorexia nervosa (AN) may also predict risk for other disordered eating behaviors, but no study has examined if PRS for AN can predict disordered eating as a global continuous measure. This study aimed to investigate whether PRS for AN predicted overall levels of disordered eating, or specific lifetime disordered eating behaviors, in an Australian adolescent female population.

METHODS

PRSs were calculated based on summary statistics from the largest Psychiatric Genomics Consortium AN genome-wide association study to date. Analyses were performed using genome-wide complex trait analysis to test the associations between AN PRS and disordered eating global scores, avoidance of eating, objective bulimic episodes, self-induced vomiting, and driven exercise in a sample of Australian adolescent female twins recruited from the Australian Twin Registry (N = 383).

RESULTS

After applying the false-discovery rate correction, the AN PRS was significantly associated with all disordered eating outcomes.

CONCLUSIONS

Findings suggest shared genetic etiology across disordered eating presentations and provide insight into the utility of AN PRS for predicting disordered eating behaviors in the general population. In the future, PRSs for EDs may have clinical utility in early disordered eating risk identification, prevention, and intervention.

Estrogen moderation of genetic influences on eating disorder symptoms during gonadarche in girls: Specific effects on binge eating

The heritability of eating disorder (ED) symptoms increases dramatically across gonadarche in girls. Past studies suggest these developmental differences could be due to pubertal activation of estrogen, but findings have been limited to only one ED symptom (i.e., binge eating). The current study examined whether estrogen contributes to gonadarcheal differences in genetic influences on overall levels of ED symptoms as well as key cognitive symptoms (i.e., weight/shape concerns) that are present across all EDs and are early risk factors for eating pathology. Given that binge eating frequently co-occurs with all of these symptoms, analyses also examined whether estrogen effects exist for overall levels of ED symptoms and body weight/shape concerns after accounting for the known effects of estrogen on genetic risk for binge eating. Participants included 964 female twins (ages 8-16) from the Michigan State University Twin Registry. Overall levels of ED symptoms were assessed with the Minnesota Eating Behavior Survey (MEBS) total score. Weight/shape concerns were assessed with a latent factor modeled using subscales from the MEBS and the Eating Disorder Examination Questionnaire. Estradiol levels were assessed with saliva samples. Twin moderation models were used to examine whether genetic influences on overall levels of ED symptoms and weight/shape concerns differed significantly across estradiol levels. Although initial models suggested modest differences in genetic influences on overall levels of ED symptoms across estradiol levels, these effects were eliminated when binge eating was accounted for in the models. In addition, weight/shape concerns did not show significant moderation of genetic influences by estradiol in models with or without binge eating. Taken together, results are significant in suggesting that individual differences in estradiol levels during gonadarche have a unique and specific impact on genetic risk for binge eating, while other etiologic factors must contribute to increased heritability of cognitive ED symptoms during this key developmental period in girls.

Predicting eating disorder and anxiety symptoms using disorder-specific and transdiagnostic polygenic scores for anorexia nervosa and obsessive-compulsive disorder

BACKGROUND

Clinical, epidemiological, and genetic findings support an overlap between eating disorders, obsessive-compulsive disorder (OCD), and anxiety symptoms. However, little research has examined the role of genetics in the expression of underlying phenotypes. We investigated whether the anorexia nervosa (AN), OCD, or AN/OCD transdiagnostic polygenic scores (PGS) predict eating disorder, OCD, and anxiety symptoms in a large developmental cohort in a sex-specific manner.

METHODS

Using summary statistics from Psychiatric Genomics Consortium AN and OCD genome-wide association studies, we conducted an AN/OCD transdiagnostic genome-wide association meta-analysis. We then calculated AN, OCD, and AN/OCD PGS in participants from the Avon Longitudinal Study of Parents and Children to predict eating disorder, OCD, and anxiety symptoms, stratified by sex (combined N = 3212-5369 per phenotype).

RESULTS

The PGS prediction of eating disorder, OCD, and anxiety phenotypes differed between sexes, although effect sizes were small. AN and AN/OCD PGS played a more prominent role in predicting eating disorder and anxiety risk than OCD PGS, especially in girls. AN/OCD PGS provided a small boost over AN PGS in the prediction of some anxiety symptoms. All three PGS predicted higher compulsive exercise across different developmental timepoints [β = 0.03 (s.e. = 0.01) for AN and AN/OCD PGS at age 14; β = 0.05 (s.e. = 0.02) for OCD PGS at age 16] in girls.

CONCLUSIONS

Compulsive exercise may have a transdiagnostic genetic etiology, and AN genetic risk may play a role in the presence of anxiety symptoms. Converging with prior twin literature, our results also suggest that some of the contribution of genetic risk may be sex-specific.

Disadvantage and disordered eating in boys: Examining phenotypic and genotype × environment associations across development

Socioeconomic disadvantage may be a significant risk factor for disordered eating, particularly for individuals with underlying genetic risk. However, little to nothing is known about the impact of disadvantage on disordered eating in boys during the critical developmental risk period. Crucially, risk models developed for girls may not necessarily apply to boys, as boys show different developmental patterns of disordered eating risk (i.e., earlier activation of genetic influences during adrenarche, an early stage of puberty). This is the first study to examine phenotypic and Genotype × Environment (G × E) effects of disadvantage in boys. Analyses examined 3,484 male twins ages 8-17 (Mage = 12.27, SD = 2.96) from the Michigan State University Twin Registry. Disordered eating (e.g., body dissatisfaction, binge eating) was measured using the parent-report Michigan Twins Project Eating Disorder Survey. Neighborhood disadvantage was measured using a census-tract level Area Deprivation Index, and family socioeconomic status was determined from parental income and education. Adrenarche status was determined using multiple indicators, including age and Pubertal Development Scale scores. G × E models suggested that genetic influences on disordered eating were activated earlier for boys experiencing familial or neighborhood disadvantage, with substantial genetic influences in early adrenarche, when genetic influences were low in more advantaged boys. Phenotypically, both neighborhood and familial disadvantage were associated with greater disordered eating for boys in late adrenarche, which could indicate a lasting impact of earlier activation of genetic influences on later risk. Results highlight disadvantage as a novel risk factor for disordered eating in boys, particularly those with genetic vulnerabilities. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Exploring the possibility of parents' broad internalizing phenotype acting through passive gene-environment correlations on daughters' disordered eating

Twin studies demonstrate significant environmental influences and a lack of genetic effects on disordered eating before puberty in girls. However, genetic factors could act indirectly through passive gene-environment correlations (rGE; correlations between parents' genes and an environment shaped by those genes) that inflate environmental (but not genetic) estimates. The only study to explore passive rGE did not find significant effects, but the full range of parental phenotypes (e.g., internalizing symptoms) that could impact daughters' disordered eating was not examined. We addressed this gap by exploring whether parents' internalizing symptoms (e.g., anxiety, depressive symptoms) contribute to daughters' eating pathology through passive rGE. Participants were female twin pairs (aged 8-14 years; M = 10.44) in pre-early puberty and their biological parents (n = 279 families) from the Michigan State University Twin Registry. Nuclear twin family models explored passive rGE for parents' internalizing traits/symptoms and twins' overall eating disorder symptoms. No evidence for passive rGE was found. Instead, environmental factors that create similarities between co-twins (but not with their parents) and unique environmental factors were important. In pre-early puberty, genetic factors do not influence daughters' disordered eating, even indirectly through passive rGE. Future research should explore sibling-specific and unique environmental factors during this critical developmental period.

Context matters: Neighborhood disadvantage is associated with increased disordered eating and earlier activation of genetic influences in girls

Emerging evidence suggests socioeconomic disadvantage may increase risk for eating disorders (EDs). However, there are very few studies on the association between disadvantage and EDs, and all have focused on individual-level risk factors (e.g., family income). Neighborhood disadvantage (i.e., elevated poverty and reduced resources in one's neighborhood) is associated with increased risk for anxiety/depression and poor physical health. To date, no studies have examined phenotypic associations between neighborhood disadvantage and disordered eating, or how any form of disadvantage may interact with genetic individual differences in risk for EDs. We examined phenotypic and etiologic associations between neighborhood disadvantage and disordered eating in 2,922 girls ages 8-17 from same-sex twin pairs recruited through the Michigan State University Twin Registry. Parents rated the twins on nine items assessing core disordered eating symptoms (e.g., weight preoccupation, binge eating), and neighborhood disadvantage was calculated from 17 indicators of contextual disadvantage (e.g., median home value, neighborhood unemployment). Puberty was measured using the Pubertal Development Scale to examine whether associations were consistent across development. At a phenotypic level, greater neighborhood disadvantage was associated with significantly greater disordered eating symptoms in girls at all stages of puberty (β = .07). Moreover, Genotype × Environment models showed that girls living in more disadvantaged neighborhoods exhibited stronger and earlier (i.e., during pre/early puberty) activation of genetic influences on disordered eating. Results highlight the critical importance of considering contextual disadvantage in research on etiology and risk for disordered eating, and the need for increased screening and treatment for EDs in disadvantaged youth. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Psychological and social risk factors associated with development of psychopathology, controlling for biological influence

PURPOSE OF REVIEW

To evaluate and summarize recent research investigating psychological, social and environmental risk factors for development of psychopathology in childhood, while controlling for biological (genetic) influences by using a matched sibling, twin or adoptee design.

RECENT FINDINGS

Nineteen studies were included, of which eleven were longitudinal and eight were cohort studies. Included studies used adequate designs and statistical methods, controlled for unmeasured confounders and, in many cases, for other measured risk factors. None of the studies used the framework for environmental factors presented in the International Classification of Functioning, Disability and Health (ICF). The outcome variable psychopathology was rarely assessed using a diagnostic standard. The findings were sorted in five themes based on included exposures: 'Social support, social rejection and perceived identity,' 'Early symptoms of psychopathology,' 'Antibiotic exposure,' 'Factors in the family' and 'Nature versus nurture'.

SUMMARY

Using twin/sibling/adoptee designs, a number of unique predictors of psychopathology were found, even when controlling for familial confounders and other specified risk factors. Future studies of psychopathology development should benefit from longitudinal, genetically sensitive designs and from use of diagnostic standards for psychopathology outcome, and should also incorporate ICF for classification of risk factors.

Gonadal Hormone Influences on Sex Differences in Binge Eating Across Development

PURPOSE OF REVIEW

Binge eating is a transdiagnostic symptom that disproportionately affects females. Sexually dimorphic gonadal hormones (e.g., estradiol, testosterone) substantially impact eating behavior and may contribute to sex differences in binge eating. We examine recent evidence for the role of gonadal hormones in binge eating risk across development.

RECENT FINDINGS

Both organizational (long-lasting impact on the central nervous system (CNS)) and activational (transient influences on the CNS) hormone effects may contribute to sex differences in binge eating. Gonadal hormones also impact within-sex variability in binge eating, with higher estradiol levels in females and higher testosterone levels in males protective across development. Emerging evidence suggests that the impact of gonadal hormones may be greatest for people with other risk factors, including genetic, temperamental (e.g., high negative affect), and psychosocial (e.g., exposure to weight-based teasing) risk. Gonadal hormones contribute to sex differences and within-sex variability in binge eating across development.

The effects of puberty on associations between mood/personality factors and disordered eating symptoms in girls

OBJECTIVE

Negative and positive urgency, anxiety, and depressive symptoms are significant factors of disordered eating (DE) symptoms in early adolescence through young adulthood. However, it is unclear how puberty-a critical developmental milestone that is associated with increased risk for DE symptoms-affects the relationship between these factors and DE symptoms, given that the role of pubertal status has rarely been considered in relation to these associations. Thus, the present study examined whether puberty moderates associations between mood/personality factors and DE in pre-adolescent and adolescent girls.

METHOD

Participants included 981 girls (aged 8-16 years) from the Michigan State University Twin Registry. Mood/personality factors, pubertal status, and DE were assessed with self-report questionnaires.

RESULTS

Puberty significantly moderated associations between several factors (negative urgency, positive urgency, trait anxiety, depressive symptoms) and the cognitive symptoms of DE (e.g., shape/weight concerns, body dissatisfaction). Associations between mood/personality factors and cognitive DE were stronger in girls with more advanced pubertal status. By contrast, no significant moderation effects were detected for mood/personality-dysregulated eating (e.g., binge eating, emotional eating) associations.

DISCUSSION

Findings identify pubertal development as an important moderator of mood/personality-DE symptom associations, especially for cognitive DE symptoms that are known to predict the later onset of clinical pathology.

The Role of the Environment in Overweight and Eating Behavior Variability: Insights from a Multivariate Twin Study

Research has emphasized the genetic basis of individual differences in body mass index (BMI); however, genetic factors cannot explain the rapid rise of obesity. Eating behaviors have been stipulated to be the behavioral expression of genetic risk in an obesogenic environment. In this study, we decompose variation and covariation between three key eating behaviors and BMI in a sample of 698 participants, consisting of 167 monozygotic, 150 dizygotic complete same-sex female twins and 64 incomplete pairs from a population-based twin registry in the southeast of Spain, The Murcia Twin Registry. Phenotypes were emotional eating, uncontrolled eating and cognitive restraint, measured by the Three Factor Eating Questionnaire and objectively measured BMI. Variation in eating behaviors was driven by nonshared environmental factors (range: 56%-65%), whereas shared environmental and genetic factors were secondary. All three eating behaviors were correlated with BMI (r = .19-.25). Nonshared environmental factors explained the covariations (Emotional eating-Uncontrolled eating: rE = .54, 95% CI [.43, .64]; BMI-Cognitive restraint: rE = .15, 95% CI [.01, .28]). In contrast to BMI, individual differences in eating behaviors are mostly explained by nonshared environmental factors, which also accounted for the phenotypic correlation between eating behaviors and BMI. Due to the sample size, analyses were underpowered to detect contributions of additive genetic or shared environmental factors to variation and covariation of the phenotypes. Although more research is granted, these results support that eating behaviors could be viable intervention targets to help individuals maintain a healthy weight.

A Narrative Review of Sex Differences in Eating Disorders: Is There a Biological Basis?

PURPOSE

Eating disorders and their core symptoms (eg, binge eating, body weight/shape concerns) disproportionately affect females, and these sex-differentiated effects become prominent during and after puberty. Although psychosocial influences such as heightened sociocultural pressures for thinness in girls and women contribute to this sex imbalance, biological factors could also play an important role.

METHODS

This narrative review summarizes evidence of biological factors underlying the sex-differentiated prevalence of eating pathology as well as within-sex variability in risk.

FINDINGS

There are sex differences in the pubertal emergence of genetic effects on eating pathology (adrenarche in males; gonadarche in females), and at least some genetic contributions to eating pathology seem to vary between the sexes. Furthermore, sex steroid hormones (eg, testosterone, estradiol, progesterone) are leading contributors to differential risk for eating pathology in males and females across the life span. Emerging data suggest that between-sex and within-sex variability in risk might occur via hormone-driven modulation (activation/deactivation) of genetic influences and neural responsiveness to food-related cues.

IMPLICATIONS

There is a biological basis to heightened risk for eating pathology in females, relative to males, as well as unique biological influences within each sex. Findings from this review highlight the importance of studying both sexes and considering sex-specific biological mechanisms that may underlie differential risk for eating pathology.