What drives the association between weight-conscious peer groups and disordered eating? Disentangling genetic and environmental selection from pure socialization effects

Relationship of Genetic Polymorphisms and Microbial Composition with Binge Eating Disorder: A Systematic Review

Humans are the result of an evolutionary process, and because of this, many biological processes are interconnected with each other. The intestine-brain axis consists of an intricately connected neuronal-neuroendocrine circuit that regulates the sensation of hunger and satiety. Genetic variations and the consumption of unnatural diets (ultra-processed foods, high contents of sugars, etc.) can override this circuit and cause addiction to certain foods and/or the inability to feel satiety in certain situations. The patients who come to consultations (mainly psychology or nutrition) in an attempt to resolve this problem sometimes fail, which leads to them looking for new strategies based on biological predisposition. This investigation aims to evaluate the genetic studies regarding the microbiota carried out in the last 12 years in humans to try to determine which genes and microbes that have been recently studied are related to patients diagnosed with binge eating disorder or compulsive eating (presenting obesity or not). The protocol followed the PRISMA statement, and the following databases were searched from 2012 until the present day: PubMed, PsycINFO, SCOPUS, and Web of Science. Twenty-four international articles were analyzed, including cross-sectional or exploratory studies; five of them referred to the microbial composition, and in nineteen, the existence of genetic polymorphisms present in binge eating disorder or in compulsive eating could be observed: DRD2, OPRM1, COMT, MC4R, BNDF, FTO, SLC6A3, GHRL, CARTPT, MCHR2, and LRP11. Even though there is still much to investigate on the subject, it must be highlighted that, in the last 4 years, a two-fold increase has been observed in potential markers and in studies related to the matter, also highlighting the importance of different analyses in relation to psychosocial factors and their interaction with the genetic and microbial factors, for which research on the matter must be continued.

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.

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.

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

The heritability of disordered eating increases during puberty; however, prior studies have largely examined a composite score of disordered eating, rather than specific symptoms. Body weight and shape concerns cut across all eating disorder diagnoses and are some of the strongest prospective risk factors for the development of eating disorders. Yet, little is known about potential developmental increases or decreases in genetic and environmental influences for these key symptoms. This study examined differences in genetic and environmental effects on a range of body weight and shape concerns during puberty and compared results to findings for overall levels of disordered eating symptoms. Participants were 926 same-sex female twins (ages 8-16) from the Michigan State University Twin Registry. Well-validated questionnaires were used to examine pubertal maturation, overall levels of disordered eating, and a range of cognitive body weight/shape constructs: body dissatisfaction, weight/shape concerns, and weight preoccupation. Findings for overall levels of disordered eating were very similar to those obtained in previous work, with significantly increased genetic effects in girls at more advanced pubertal development. Importantly, these same pubertal increases in genetic influences were observed for body dissatisfaction and weight/shape concerns. However, no pubertal moderation of genetic effects was observed for weight preoccupation; instead, pubertal moderation of nonshared and shared environmental effects was observed. Our findings point to differences in the extent to which genetic and environmental factors contribute to various cognitive body weight and shape symptoms during puberty.

Non-Suicidal Self-Injury and Eating Disordered Behaviors: An Update on What We Do and Do Not Know

PURPOSE OF REVIEW

The current report aims to summarize recent advances about the relationship between non-suicidal self-injury (NSSI) and eating disordered (ED) behaviors and highlights meaningful directions for future research.

RECENT FINDINGS

While there is solid evidence indicating a robust cross-sectional association between NSSI and ED behaviors, emerging evidence suggests that the temporal relationship between these behaviors may be bidirectional. Shared functions and risk factors may explain why these behaviors often co-develop. At the same time, little is still known about the psychosocial consequences of comorbid NSSI and ED engagement, and there is a lack of intervention studies that target these behaviors simultaneously. It is well-established that NSSI and ED behaviors frequently co-occur. The field should now turn to longitudinal designs to advance our understanding of the longer-term developmental and the shorter-term momentary relationship of these behaviors in daily life. Providing insight into these areas will help guide the deployment of evidence-based interventions that match the needs of clients who report comorbid NSSI and ED behaviors.

Elucidating factors underlying parent-offspring similarity in eating pathology in pre- and early puberty: Exploring the possibility of passive gene-environment correlation

Familial resemblance in eating pathology is typically attributed to parents providing an environment that leads to the development of eating pathology. However, offspring raised by biological parents receive both their environment and genes from their parents, raising the possibility that genetic influences, environmental influences, and/or gene-environment interplay may account for familial resemblance. Past studies have not explored the possibility of parents' genes influencing the environment they provide (i.e., passive gene-environment correlations or "passive rGE"). If present, passive rGE is most likely to "hide" in estimates of shared environmental influence in classical twin models. The current study used a nuclear twin family design to explore the possibility of passive rGE during pre- and early puberty when past studies have demonstrated the importance of shared environmental influence. Additionally, the present study explored whether sibling-specific (i.e., influences specific to the twin generation) or family-specific (i.e., "cultural" influences within the home) environmental influences account for shared environmental influences found in past studies. Participants included preearly pubertal same-sex female twins and their biological parents (N = 547 families) from the Minnesota Twin Family Study and the Michigan State University Twin Registry. Disordered eating was assessed with self-report measures in the twins and parents. Pubertal status was determined using an established cut-off on a self-report measure. Passive rGE was not indicated in this study of pre- and early pubertal twins. Instead, sibling-specific shared environmental and nonshared environmental influences were most influential. Future research should work to identify the sibling-specific environmental influences that contribute to sibling similarity in disordered eating. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Interaction of hormonal and social environments in understanding body image concerns in adolescent girls

During adolescence, peer approval becomes increasingly important and may be perceived as contingent upon appearance in girls. Concurrently, girls experience hormonal changes, including an increase in progesterone. Progesterone has been implicated in affiliative behavior but inconsistently associated with body image concerns. The current study sought to examine whether progesterone may moderate the association between perceived social pressures to conform to the thin ideal and body image concerns. Secondary analyses were conducted in cross-sectional data from 813 girls in early puberty and beyond (ages 8-16) who completed assessments of the peer environment, body image concerns, and progesterone. Models for mediation and moderation were examined with BMI, age, and menarcheal status as covariates. Belief that popularity was linked to appearance and the experience of weight-related teasing were both positively associated with greater body image concerns, but neither was associated with progesterone once adjusting for covariates. Progesterone significantly interacted with perceived social pressures in predicting body image concerns. At higher progesterone levels, appearance-popularity beliefs and weight-related teasing were more strongly related to body image concerns than they were at lower progesterone levels. Findings support a moderating role for progesterone in the link between social pressures and body image concerns in girls. This study adds to a growing literature examining how girls' hormonal environments may modulate responses to their social environments. Longitudinal and experimental work is needed to understand temporal relations and mechanisms behind these associations.

Estrogen moderates genetic influences on binge eating during puberty: Disruption of normative processes?

Puberty is a critical period for changes in genetic effects for binge eating in girls. Previous twin studies show increases in genetic influences on binge eating from prepuberty (∼0%) to midpuberty and beyond (∼50%). However, little is known about the factors that drive these shifts in genetic effects. A small pilot study showed that pubertal activation of estrogen may contribute to increases in genetic influences, possibly via hormonally induced changes in gene expression. However, large-scale studies investigating hormone effects on genetic risk are lacking. Thus, the purpose of the present study was to examine the effects of estrogen on genetic influences for binge eating in 964 female twins (ages 8-16 years) from the Michigan State University Twin Registry. Binge eating was assessed with the Minnesota Eating Behaviors Survey, whereas afternoon saliva samples were assayed for estradiol levels using standard enzyme immunoassays. Twin moderation models showed substantial differences in genetic influences on binge eating across estradiol levels. Stronger genetic effects were observed at lower (rather than higher) estradiol levels, even when controlling for the effects of age, body mass index, the physical changes of puberty, and the onset of menses. Overall, findings suggest that comparatively lower levels of estradiol during this critical period may disrupt normative developmental processes and enhance genetic influences on binge eating. (PsycINFO Database Record

The significant effects of puberty on the genetic diathesis of binge eating in girls

OBJECTIVE

Recent data show significant phenotypic and genetic associations between ovarian hormones and binge eating in adulthood. Theories of hormonal risk focus on puberty and the possibility that hormone activation induces changes in genetic effects that then lead to differential risk for binge eating in postpuberty and adulthood. Although this theory is difficult to test in humans, an indirect test is to examine whether genetic influences on binge eating increase during the pubertal period in girls. Prior work has shown pubertal increases in genetic influences on overall disordered eating symptoms, but no study to date has examined binge eating. The present study was the first to examine these increases for binge eating.

METHODS

Participants included 1,568 female twins (aged 8-25 years) from the Michigan State University Twin Registry. Binge eating and pubertal development were assessed with self-report questionnaires.

RESULTS

Twin moderation models showed significant linear increases in genetic effects from prepuberty (5%) to postpuberty (42%), even after controlling for the effects of age and body mass index.

DISCUSSION

Results provide critical support for increased genetic influences on binge eating during puberty. Additional studies are needed to identify hormonal mechanisms and fully test contemporary models of ovarian hormone risk.

Socialization and selection effects in the association between weight conscious peer groups and thin-ideal internalization: A co-twin control study

Affiliation with weight conscious peer groups is theorized to increase thin-ideal internalization through socialization processes. However, selection effects could contribute if genetic and/or environmental predispositions lead to affiliation with weight conscious peers. Co-twin control methodology was used to examine socialization and selection effects in 614 female twins (ages 8-15) from the Michigan State University Twin Registry (MSUTR). Thin-ideal internalization and peer group characteristics were assessed via self-report questionnaires. Results suggested the presence of both socialization and selection effects. In terms of socialization, twins who reported increased exposure to weight conscious peers relative to their co-twins had elevated thin-ideal internalization scores, regardless of zygosity. However, associations between weight conscious peers and thin-ideal internationalization within twin pairs were attenuated, suggesting that genetic and shared environmental selection effects also contribute. Findings significantly extend previous work by confirming the presence of socialization processes and highlighting selection processes to be examined in future longitudinal research.

The dimensional nature of eating pathology: Evidence from a direct comparison of categorical, dimensional, and hybrid models

Eating disorders are conceptualized as categorical rather than dimensional in the current major diagnostic system (Diagnostic and Statistical Manual of Mental Disorders; 5th ed.; American Psychiatric Association, 2013) and in many previous studies. However, previous research has not critically evaluated this assumption or tested hybrid models (e.g., modeling latent variables with both dimensional and categorical features). Accordingly, the current study directly compared categorical, dimensional, and hybrid models for eating pathology in a large, population-based sample. Participants included 3,032 female and male twins (ages 9-30 years) from the Michigan State University Twin Registry. The Minnesota Eating Behaviors Survey was used to assess disordered eating symptoms including body dissatisfaction, weight preoccupation, binge eating, and compensatory behaviors. Results showed that dimensional models best fit the data in the overall sample as well as across subgroups divided by sex and pubertal status (e.g., prepubertal vs. postpubertal). It is interesting to note that the results favored more categorical models when using a case-control subset of our sample with participants who either endorsed substantial eating pathology or no/little eating pathology. Overall, findings provide support for a dimensional conceptualization of eating pathology and underscore the importance of using community samples to capture the full range of severity of eating pathology when investigating questions about taxonomy. (PsycINFO Database Record