Shared genetic influences between eating disorders and gastrointestinal disease in a large, population-based sample of adult women and men

BACKGROUND

Some preliminary research suggests higher rates of gastrointestinal disease in individuals with eating disorders (EDs). However, research is limited, and it remains unknown what etiologic factors account for observed associations. This was the first study to examine how EDs and dimensional ED symptoms (e.g. body dissatisfaction, binge eating) are phenotypically and etiologically associated with gastrointestinal disease in a large, population-based twin sample.

METHODS

Adult female (N = 2980) and male (N = 2903) twins from the Michigan State University Twin Registry reported whether they had a lifetime ED (anorexia nervosa, bulimia nervosa, or binge-eating disorder) and completed a measure of dimensional ED symptoms. We coded the presence/absence of lifetime gastrointestinal disease (e.g. inflammatory bowel disease) based on responses to questions regarding chronic illnesses and medications. We first examined whether twins with gastrointestinal disease had higher rates of EDs and ED symptoms, then used correlated factors twin models to investigate genetic and environmental contributions to the overlap between disorders.

RESULTS

Twins with gastrointestinal disease had significantly greater dimensional ED symptoms (β = 0.21, p < 0.001) and odds of a lifetime ED (OR 2.90, p = 0.001), regardless of sex. Shared genetic factors fully accounted for the overlap between disorders, with no significant sex differences in etiologic associations.

CONCLUSIONS

Comorbidity between EDs and gastrointestinal disease may be explained by overlap in genetic influences, potentially including inflammatory genes implicated in both types of disorders. Screening for gastrointestinal disease in people with EDs, and EDs in those with gastrointestinal disease, is warranted.

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.

Ovarian Hormones and Binge Eating in Adulthood: Summary of Findings and Implications for Individual Differences in Risk in Women

Ovarian hormone influences on general food intake have been studied in animals for 60+ years. Yet, extensions of these data to key eating disorder symptoms in humans (e.g., binge eating (BE)) have only recently occurred. In this article, we summarize findings from studies examining the effects of ovarian hormones on BE. Findings suggest ovarian hormones contribute to BE in animals and humans, although studies are few in number, and effects are not present in all women or all animals exposed to high-risk hormonal milieus. Differences in susceptibility may be due to gene x hormone interactions that can explain why some, but not all, women/females develop BE in the presence of risky hormonal environments.

Associations between household income and disordered eating differ across sex and racial identity in a population-based sample of adults

BACKGROUND

Most research on socioeconomic status (SES) and eating disorders (EDs) has focused on young White women. Consequently, little is known regarding how SES may relate to EDs/disordered eating in older adults, men, or people with different racial identities. We examined whether associations between SES and EDs/disordered eating differed across age, sex, and racial identity in a large, population-based sample spanning early-to-later adulthood.

METHODS

Analyses included 2797 women and 2781 men ages 18-65 (Mage  = 37.41, SD = 7.38) from the population-based Michigan State University Twin Registry. We first examined associations between SES and dimensional ED symptoms, binge eating (BE), and self-reported ED diagnoses across age and sex in the full sample. We then examined the impact of racial identity on associations by conducting within- and between-group analyses among Black and White participants.

RESULTS

In the full sample, lower SES was associated with significantly greater odds of BE and lifetime EDs in men, but not women, across adulthood. The association between lower SES and greater BE risk was stronger for Black men than for White men, though significant in both groups. Conversely, Black women showed a positive association between SES and dimensional ED symptoms that significantly differed from effects for Black men and White women.

CONCLUSIONS

Associations between socioeconomic disadvantage and EDs/disordered eating may be particularly robust for men in adulthood, especially men with a marginalized racial identity. Oppositely, Black women may encounter social pressures and minority stress in higher SES environments that could contribute to somewhat heightened ED risk.

PUBLIC SIGNIFICANCE

Little is known regarding how associations between socioeconomic status (SES) and eating disorders (EDs) may differ across age/sex or racial identity. We found lower SES was associated with greater odds of a lifetime ED or binge eating in men only, with a particularly strong association between lower SES and binge eating for Black men. Results highlight the importance of examining how SES-ED associations may differ across other aspects of identity.

The organizational role of ovarian hormones during puberty on risk for binge-like eating in rats

Puberty is a high-risk period for the development of dysregulated eating, including binge eating. While risk for binge eating in animals and humans increases in both males and females during puberty, the increased prevalence is significantly greater in females. Emerging data suggest that the organizational effects of gonadal hormones may contribute to the female preponderance of binge eating. In this narrative review, we discuss studies conducted in animals that have examined these organizational effects as well as the neural systems that may serve as intermediary mechanisms. Relatively few studies have been conducted, but data thus far suggest that pubertal estrogens may organize risk for binge eating, potentially by altering key circuits in brain reward pathways. These promising results highlight the need for future studies to directly test organizational effects of pubertal hormones using hormone replacement techniques and circuit-level manipulations that can identify pathways contributing to binge eating across development.

Binge Eating Risk During Midlife and the Menopausal Transition: Sensitivity to Ovarian Hormones as Potential Mechanisms of Risk

PURPOSE OF REVIEW

Recent research suggests that binge eating may be more prevalent among women in midlife than previously believed. The menopausal transition, an important developmental stage during midlife, is characterized by substantial fluctuations and eventual decreases in ovarian hormones that may contribute to increased risk. This narrative review summarizes findings from studies of binge eating during midlife and menopause and discusses the potential role of ovarian hormones in binge eating risk.

RECENT FINDINGS

Studies are few in number and findings are mixed, with only some studies showing increased binge eating during midlife and the menopausal transition. Sensitivity to ovarian hormones, potentially through gene x hormone interactions, may influence who experiences increased binge eating risk and could help explain mixed findings in the field. Future studies of hormone sensitivity and gene x hormone interactions are needed to further elucidate midlife and menopausal risk for binge eating in women.

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).

A cotwin control study of associations between financial hardship and binge eating phenotypes during COVID-19

BACKGROUND

COVID-19 was associated with significant financial hardship and increased binge eating (BE). However, it is largely unknown whether financial stressors contributed to BE during the pandemic. We used a longitudinal, cotwin control design that controls for genetic/environmental confounds by comparing twins in the same family to examine whether financial hardship during COVID-19 was associated with BE.

METHODS

Female twins (N = 158; M_age  = 22.13) from the Michigan State University Twin Registry rated financial stressors (e.g., inability to afford necessities) daily for 49 consecutive days during COVID-19. We first examined whether financial hardship was associated with BE phenotypes across the full sample. We then examined whether cotwins who differed on financial hardship also differed in BE.

RESULTS

Participants who experienced greater mean financial hardship across the study had significantly greater dimensional BE symptoms, and participants who experienced greater financial hardship on a given day reported significantly more emotional eating that day. These results were replicated in cotwin control analyses. Twins who experienced more financial hardship than their cotwin across the study reported greater dimensional BE symptoms than their cotwin, and participants who experienced more financial hardship than their cotwin on a given day reported greater emotional eating that day. Results were identical when restricting analyses to monozygotic twins, suggesting associations were not due to genetic confounds.

CONCLUSIONS

Results suggest that BE-related symptoms may be elevated in women who experienced financial hardship during COVID-19 independent of potential genetic/environmental confounds. However, additional research in larger samples is needed.

PUBLIC SIGNIFICANCE

Little is known regarding how financial difficulties during the COVID-19 pandemic may have contributed to increased binge eating (BE). We found preliminary evidence that financial hardship during COVID-19 may be associated with greater rates of BE-related symptoms even when comparing twins from the same family. While additional research is needed, results suggest that people who experienced financial hardship during COVID-19 may be at increased risk for BE.

Sociocultural correlates of eating pathology in college women from US and Iran

Objective

The buffering role of the hijab as a protective factor against eating pathology has been questioned in countries where wearing the hijab is compulsory, such as Iran; and, cross-cultural comparisons of body image in Iranian and Western women are sparse. Consequently, we examined sociocultural correlates of eating pathology in US and Iranian women.

Method

College women from the US (n = 709) and Iran (n = 331) completed the Eating Disorder Examination-Questionnaire (EDE-Q) and the Sociocultural Attitude Toward to Appearance Questionnaire-4 (SATAQ-4). Prior to examining main hypotheses, we evaluated whether the scales perform similarly (i.e., establish measurement invariance) by culture.

Results

The EDE-Q and SATAQ-4 were not invariant by culture indicating that the scales performed differently across groups, so separate analyses were conducted in each sample. Thin-ideal internalization and pressures for thinness were significant positive predictors of eating pathology in both US and Iranian women.

Conclusion

Both pressures for thinness and thin-ideal internalization appear to be relevant to eating pathology in women from both cultures. However, there may be important cross-cultural differences in the interpretation or experience of these constructs. Further understanding of this measurement non-invariance and the ways in which Iranian women may be uniquely impacted by Western values of appearance is a critical next step.

Risk for midlife psychosis in women: critical gaps and opportunities in exploring perimenopause and ovarian hormones as mechanisms of risk

Women show a heightened risk for psychosis in midlife that is not observed in men. The menopausal transition (i.e. perimenopause) and accompanying changes in ovarian hormones are theorized to account for this midlife increase in risk. This narrative review aims to empirically examine these theories by reviewing studies of midlife and perimenopausal psychosis risk in women and potential ovarian hormone mechanisms of effects. Clinical and pre-clinical studies examining the effects of midlife age, menopausal stage, and ovarian hormones across adulthood on psychosis risk were identified. Synthesis of this body of work revealed that the peak ages of midlife psychosis risk in women overlap with the age range of key menopausal stages (especially the perimenopausal transition), although studies directly assessing menopausal stage are lacking. Studies examining ovarian hormone effects have almost exclusively focused on earlier developmental stages and events (e.g. pregnancy, the menstrual cycle) and show increases in psychotic symptoms in women and female rats during periods of lower estradiol levels. Estrogen treatment also tends to enhance the effects of neuroleptics in females across species at various reproductive phases. Initial data are promising in suggesting a role for menopausal stage and ovarian hormones in psychosis risk. However, critical gaps in our knowledge base remain, as there is a tendency to rely on indirect and proxy measures of menopausal status and hormones. Opportunities for future research are discussed with the goal of increasing research in this critical area of women's health.

Elucidating early pubertal timing effects on disordered eating symptoms in young adult women

INTRODUCTION

Early pubertal timing increases risk for disordered eating (DE) in females, but the extent to which associations persist after puberty and are relevant to all types of DE symptoms is unclear. Factors that link pubertal timing and DE also remain unknown, although leading theories posit that adiposity and body-focused psychosocial factors play a key role. Thus, this study examined pubertal timing effects on several types of DE symptoms in young adult women and evaluated whether body mass index (BMI), pressures for thinness, thin-ideal internalization, and/or history of weight-based teasing account for such associations.

METHODS

This study included a racially and ethnically diverse sample of 342 female college students (M_age = 20.44, SD = 3.46). Women retrospectively reported their age at onset of menses, which served as the pubertal timing indicator, and completed self-report questionnaires on DE symptoms, perceived pressures for thinness, thin-ideal internalization, and history of weight-based teasing. BMI was calculated from height/weight measurements.

RESULTS

Earlier pubertal timing was associated with body dissatisfaction and binge eating, but not other DE symptoms (dieting, excessive exercise, muscle building) in young adult women. BMI accounted for pubertal timing effects on body dissatisfaction, whereas none of the examined factors explained pubertal timing effects on binge eating.

CONCLUSIONS

Earlier pubertal timing may exert long-term effects on only some DE symptoms in women, and the etiologic factors underlying pubertal timing effects on DE outcomes may differ across symptom types.

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 effects of puberty and ovarian hormone removal on developmental trajectories of palatable food and chow intake in female rats

OBJECTIVE

Palatable food (PF) intake is significantly greater in females than males and increases during adolescence. Previous data suggest that puberty and ovarian hormones may contribute to these sex and developmental differences, but few studies have examined this possibility. The aim of the current study was to address these gaps by examining trajectories of PF and chow intake during pre-puberty, puberty, and adulthood in intact female rats (Study 1) as well as in those receiving pre-pubertal ovariectomies (P-OVX) (Study 2).

METHOD

We examined our study aims using archival data from 66 intact Sprague-Dawley female rats (Study 1) and 77 P-OVX and 79 intact Sprague-Dawley female rats (Study 2). PF and chow intake were measured using a free-choice, intermittent exposure paradigm in which rats were exposed to both food types starting in pre-puberty and continuing into adulthood.

RESULTS

Mixed linear models revealed a specific effect of puberty on PF intake in both studies. PF intake increased substantially during puberty in all rats, but increases were particularly pronounced in P-OVX rats in Study 2. By contrast, chow intake increased significantly during pre-puberty (rather than puberty) in both studies, and these increases were relatively unaffected by P-OVX.

DISCUSSION

Findings confirm a specific effect of puberty and ovarian hormone removal on PF intake in female rats. Differential trajectories of PF versus chow intake highlight potential reward-based processes in pubertal and ovarian hormone effects on PF intake in females.

Ovarian Hormones and Reward Processes in Palatable Food Intake and Binge Eating

Ovarian hormones are associated with risk for binge eating in women. Recent animal and human studies suggest that food-related reward processing may be one set of neurobiological factors that contribute to these relationships, but additional studies are needed to confirm and extend findings.

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.

Low testosterone is associated with dysregulated eating symptoms in young adult men

OBJECTIVE

Extant animal and human data indicate that natural variation in circulating levels of testosterone may contribute to differential risk for dysregulated eating among males. Indeed, testosterone ablation in postpubertal male rodents results in stimulatory effects on sweet-taste preferences, and lower levels of circulating testosterone in adolescent boys have been found to predict dysregulated eating symptoms during mid-to-late puberty. Nonetheless, no prior study has examined whether lower testosterone is associated with dysregulated eating in adulthood. The current study examined this possibility.

METHOD

Participants were 154 young adult men (ages = 18-33) from a large Southwestern University. The Eating Disorder Examination Questionnaire, Eating Pathology Symptoms Inventory, and Loss of Control Over Eating Scale were used to assess three types of dysregulated eating symptoms: eating concerns, binge eating, and loss-of-control eating. Afternoon saliva samples were assayed for testosterone using high-sensitive enzyme immunoassays.

RESULTS

Consistent with animal data and prior research in adolescent boys, men with lower testosterone reported significantly higher levels of dysregulated eating symptoms even after controlling for depressive symptoms, body mass index, and age.

DISCUSSION

Lower testosterone concentrations might serve as a sex-specific biological factor that contributes to dysregulated eating among men.

The Disruptive Effects of Estrogen Removal before Puberty on Risk for Binge Eating in Female Rats

Recent research suggests that estrogen is protective against binge eating in adult females, and that pubertal estrogen may be critical for these effects. Nonetheless, to date, no study has examined the role of pubertal estrogen in adult binge eating phenotypes in females, potentially due to difficulties experimentally manipulating estrogen in humans to examine causal effects. We used a novel animal model to examine whether estrogen removal prior to puberty (via pre-pubertal ovariectomy (P-OVX)) increases rates of binge eating prone (BEP) phenotypes in adulthood in females. A total of 77 P-OVX and 79 intact rats were followed from pre-puberty into adulthood and phenotyped for BEP status in adulthood. Results showed significantly increased rates (~2-8x higher) of adult BEP phenotypes in P-OVX as compared to intact rats. Findings confirm that estrogen removal substantially increases later risk for binge eating in females, potentially by disrupting typical adolescent brain development.

Examining associations between emotion-based rash action and dysregulated eating symptoms in men and women

Negative urgency (NU: tendency to act rashly when distressed) is the facet of impulsive personality that has been most predictive of binge eating, but less is known about the relative role of positive urgency (PU: tendency to act rashly in response to positive emotions). In addition, most studies have exclusively focused on women and the examination of pathological eating outcomes, using a dimensional symptom approach, has been somewhat limited. This study aimed to replicate and extend upon prior work. We examined the extent to which NU and/or PU are uniquely associated with dysregulated eating, using a latent factor comprised of dimensional symptoms, and directly tested whether effects differ by sex. Two independent cross-sectional samples of women and men were used (Sample 1: Midwestern university, 437 females, 348 males; Sample 2: Southwestern university, 301 females, 236 males). NU and PU were assessed with the UPPS-P Impulsive Behavior Scale, and dysregulated eating symptoms (i.e., binge eating, loss of control eating, eating concerns) were assessed with well-validated self-report questionnaires. Although both NU and PU showed significant positive associations with dysregulated eating, NU showed the strongest unique relationship with dysregulated eating in both samples. The relative role of PU was weakened in Sample 1 and completely attenuated in Sample 2 once its shared variance with NU was accounted for. All results were similar in men and women. Overall, findings continue to suggest that NU is the form of impulsivity that is most relevant to dysregulated eating in both men and women.

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.

Disordered Eating in Asian American Women: Sociocultural and Culture-Specific Predictors

Asian American women demonstrate higher rates of disordered eating than other women of color and comparable rates to European American women. Research suggests that leading sociocultural predictors, namely, pressures for thinness and thin-ideal internalization, are predictive of disordered eating in Asian American women; however, no known studies have tested the intersection of sociocultural and culture-specific variables (e.g., ethnic identity, biculturalism, and acculturative stress) to further elucidate disordered eating risk in this vulnerable, understudied group. Accordingly, this project used path analysis to simultaneously examine the role of sociocultural and culture-specific effects on disordered eating in Asian American college women (N = 430). Self-report measures assessing disordered eating, sociocultural (pressures for thinness, thin-ideal internalization), and culture-specific (ethnic identity, biculturalism, acculturative stress) variables revealed that a number of sociocultural and culture-specific factors are predictive of disordered eating. Consistent with prior research, heightened perceived pressures for thinness and thin-ideal internalization were predictive of disordered eating, and thin-ideal internalization partially mediated the relationship between pressures for thinness and disordered eating. Acculturative stress predicted disordered eating and fully accounted for the inverse relationship between biculturalism and disordered eating. Overall, findings highlighted the salience of sociocultural predictors for disordered eating in Asian American women and identified biculturalism and acculturative stress as culture-specific contributors that may uniquely impact vulnerability to disordered eating in Asian American women. Thus, the combined consideration of sociocultural and culture-specific factors may be important in disordered eating research and in the development of individualized treatment plans for Asian American women.

The Role of Distinct Facets of Perfectionism and Sociocultural Idealization of Thinness on Disordered Eating Symptoms

Introduction: Perfectionism is a multidimensional personality style implicated in risk for disordered eating (DE), yet the types of perfectionism most predictive of DE and how perfectionistic tendencies lead to the development of DE remains less clear. This study aimed to determine the types of perfectionism most strongly associated with DE and whether perceived pressures for thinness and thin-ideal internalization serve as intervening variables that explain associations between perfectionism and DE.

Methods: An ethnically diverse sample of female college students (n = 154–292) completed well-validated self-report questionnaires assessing overall DE symptoms, perfectionism, and two sociocultural factors: pressures for thinness and thin-ideal internalization.

Results: Only perfectionism constructs encompassed under the “maladaptive evaluative concerns” domain were significantly associated with DE. Double mediation models indicated that heightened pressures for thinness and thin-ideal internalization fully mediate perfectionism-DE associations.

Discussion: Results suggest that disorder-specific risk factors related to idealization of thinness may be important for understanding how a transdiagnostic factor, like perfectionism, results in DE.

Perinatal testosterone contributes to mid-to-post pubertal sex differences in risk for binge eating in male and female rats

Exposure to testosterone early in life may contribute to sex differences and pubertal changes in risk for eating pathology (i.e., females > males, after pubertal onset). Specifically, perinatal testosterone permanently alters brain structure/function and drives the masculinization of several sex-differentiated behaviors. However, the effects of perinatal testosterone are often not evident until puberty when increases in gonadal hormones activate the expression of sex typical behavior, including eating behaviors (e.g., chow intake; saccharin preference) in rodents. Despite perinatal testosterone's masculinizing effects on general feeding behavior, it remains unknown if perinatal testosterone exposure contributes to sex differences in pathological eating. The current study addressed this gap by examining whether perinatal testosterone exposure decreases risk for binge eating proneness after pubertal onset in male and female rats. Sprague-Dawley rats (n = 40 oil-treated control females; n = 39 testosterone-treated females; n = 40 oil-treated control males) were followed longitudinally across pre-to-early puberty, mid-to-late puberty, and adulthood. The binge eating prone (BEP)/binge eating resistant (BER) rodent model was used to identify individual differences in binge eating proneness across the dimensional spectrum. As expected, testosterone-treated females and control males showed masculinized (i.e., lower) risk for binge eating as compared to control females, but only after midpuberty. These animal data are significant in suggesting that perinatal testosterone exposure may protect against binge eating and underlie sex differences in binge eating prevalence during and after puberty. (PsycINFO Database Record

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.

Expanding the developmental boundaries of etiologic effects: The role of adrenarche in genetic influences on disordered eating in males

Genetic influences on disordered eating (DE) increase across age and puberty in girls, an effect that is at least partially due to ovarian hormone activation. However, development shifts in genetic effects have not been detected in boys; genetic influences have been found to be relatively constant from prepuberty to adulthood, suggesting that gonadal hormones may be less important. One caveat is that studies have examined males ages 10 or older. Genetic effects on DE may emerge earlier in boys, such as during adrenarche, when androgens begin to increase but the physical changes of puberty are not yet observable. The current study investigated this hypothesis in 1,212 male twins (ages 6-28) from the Michigan State University Twin Registry. Results supported a potential role of adrenarche, as genetic influences on DE increased during middle childhood, prior to the external physical changes of puberty. Specifically, genetic influences on DE were negligible (0%) in twins during pre- to early adrenarche, but increased incrementally across advancing adrenarche (17% to 44%) and into early puberty (57%). Genetic effects then remained stable into midpuberty and postpuberty (58%), suggesting that nearly all of the genetic effects on DE become prominent during adrenarche in males. Findings suggest that genetic effects on DE emerge sooner in boys than the midpubertal activation that is consistently found in girls. These data highlight a potentially important role for adrenarche in the genetic diathesis for DE in males and a need to examine younger ages in studies of developmental effects. (PsycINFO Database Record

Facets of Impulsivity and Compulsivity in Women with Anorexia Nervosa

This study sought to investigate independent associations of impulsivity and compulsivity with eating disorder (ED) symptoms. Women (N = 81) with full or subthreshold Diagnostic and Statistical Manual of Mental Disorders IV anorexia nervosa (AN) completed a semi-structured interview and self-report questionnaires. Multiple regression analyses were conducted using ED symptoms as dependent variables and facets of impulsivity and compulsivity as predictor variables (controlling for body mass index and AN diagnostic subtype). For impulsivity facets, lack of perseverance was uniquely associated with eating concern, shape concern and restraint, whereas negative urgency was uniquely associated with eating concern and frequency of loss of control eating; neither sensation seeking nor lack of premeditation was uniquely associated with any ED variables. Compulsivity was uniquely associated with restraint, eating concern and weight concern. Results support independent associations of impulsivity and compulsivity with ED symptoms in adults with AN, suggesting potential utility in addressing both impulsive and compulsive processes in treatment. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

Sex Differences in Binge Eating: Gonadal Hormone Effects Across Development

Eating disorders are highly sexually differentiated disorders that exhibit a female predominance in risk. Most theories focus on psychosocial explanations to the exclusion of biological/genetic influences. The purpose of this descriptive review is to evaluate evidence from animal and human studies in support of gonadal hormone effects on sex differences in binge eating. Although research is in its nascent stages, findings suggest that increased prenatal testosterone exposure in males appears to protect against binge eating. Although pubertal testosterone may exert additional protective effects, the prenatal period is likely critical for the decreased risk observed in males. By contrast, studies indicate that, in females, it is the lack of prenatal testosterone coupled with the organizational effects of pubertal ovarian hormones that may lead to increased binge eating. Finally, twin data suggest that changes in genetic risk may underlie these hormone influences on sex differences across development.

Molecular Genetic Studies of Eating Disorders: Current Status and Future Directions

We review association studies that have examined the genetic basis of eating disorders. Overall, findings suggest that serotonin, brain-derived neurotrophic factor, and estrogen genes may be important for the development of the disorders. These neuronal systems influence behavioral and personality characteristics (e.g., anxiety, food intake) that are disrupted in eating disorders. Future studies would benefit from larger sample sizes and inclusion of behavioral and personality covariates in analyses. Consideration of the mechanisms of genetic effects and interactions between genes and environment is also needed to extend conceptualizations of the genetic basis of these disorders.

Research Review: What we have learned about the causes of eating disorders - a synthesis of sociocultural, psychological, and biological research

BACKGROUND

Eating disorders are severe psychiatric disorders with a complex etiology involving transactions among sociocultural, psychological, and biological influences. Most research and reviews, however, focus on only one level of analysis. To address this gap, we provide a qualitative review and summary using an integrative biopsychosocial approach.

METHODS

We selected variables for which there were available data using integrative methodologies (e.g., twin studies, gene-environment interactions) and/or data at the biological and behavioral level (e.g., neuroimaging). Factors that met these inclusion criteria were idealization of thinness, negative emotionality, perfectionism, negative urgency, inhibitory control, cognitive inflexibility, serotonin, dopamine, ovarian hormones. Literature searches were conducted using PubMed. Variables were classified as risk factors or correlates of eating disorder diagnoses and disordered eating symptoms using Kraemer et al.'s (1997) criteria.

FINDINGS

Sociocultural idealization of thinness variables (media exposure, pressures for thinness, thin-ideal internalization, thinness expectancies) and personality traits (negative emotionality, perfectionism, negative urgency) attained 'risk status' for eating disorders and/or disordered eating symptoms. Other factors were identified as correlates of eating pathology or were not classified given limited data. Effect sizes for risk factors and correlates were generally small-to-moderate in magnitude.

CONCLUSIONS

Multiple biopsychosocial influences are implicated in eating disorders and/or disordered eating symptoms and several can now be considered established risk factors. Data suggest that psychological and environmental factors interact with and influence the expression of genetic risk to cause eating pathology. Additional studies that examine risk variables across multiple levels of analysis and that consider specific transactional processes amongst variables are needed to further elucidate the intersection of sociocultural, psychological, and biological influences on eating disorders.

Differential mesocorticolimbic responses to palatable food in binge eating prone and binge eating resistant female rats

Binge eating is a key symptom of many eating disorders (e.g. binge eating disorder, bulimia nervosa, anorexia nervosa binge/purge type), yet the neurobiological underpinnings of binge eating are poorly understood. The mesocorticolimbic reward circuit, including the nucleus accumbens and the medial prefrontal cortex, is likely involved because this circuit mediates the hedonic value and incentive salience of palatable foods (PF). Here we tested the hypothesis that higher propensity for binge eating is associated with a heightened response (i.e., Fos induction) of the nucleus accumbens and medial prefrontal cortex to PF, using an animal model that identifies binge eating prone (BEP) and binge eating resistant (BER) rats. Forty adult female Sprague-Dawley rats were given intermittent access to PF (high fat pellets) 3×/week for 3 weeks. Based on a pattern of either consistently high or consistently low PF consumption across these feeding tests, 8 rats met criteria for categorization as BEP, and 11 rats met criteria for categorization as BER. One week after the final feeding test, BEP and BER rats were either exposed to PF in their home cages or were given no PF in their home cages for 1h prior to perfusion, leading to three experimental groups for the Fos analysis: BEPs given PF, BERs given PF, and a No PF control group. The total number of Fos-immunoreactive (Fos-ir) cells in the nucleus accumbens core and shell, and the cingulate, prelimbic, and infralimbic regions of the medial prefrontal cortex was estimated by stereological analysis. PF induced higher Fos expression in the nucleus accumbens shell and core and in the prelimbic and infralimbic cortex of BEP rats compared to No PF controls. Throughout the nucleus accumbens and medial prefrontal cortex, PF induced higher Fos expression in BEP than in BER rats, even after adjusting for differences in PF intake. Differences in the neural activation pattern between BEP and BER rats were more robust in prefrontal cortex than in nucleus accumbens. These data confirm that PF activates brain regions responsible for encoding the incentive salience and hedonic properties of PF, and suggest that binge eating proneness is associated with enhanced responses to PF in brain regions that exert executive control over food reward.

Age differences in prenatal testosterone's protective effects on disordered eating symptoms: developmental windows of expression?

Prenatal testosterone exposure may be protective against disordered eating. However, prior studies have produced mixed results. Developmental differences in prenatal testosterone's protective effects on disordered eating may explain these discrepancies. Indeed, studies have differed in the age of participants assessed, with data supporting prenatal testosterone effects on disordered eating in early adolescent and young adult samples but not in late adolescence. The present studies are the first to investigate age differences in prenatal testosterone's protective effects on disordered eating. Two indirect markers of higher prenatal testosterone were examined: (a) lower finger-length ratios (Study 1: index [2D]/ring [4D] finger [2D:4D]) and (b) lower disordered eating in female s from opposite-sex twin pairs (who are thought to be exposed to higher prenatal testosterone from their male co-twin) relative to female controls (Study 2). Participants were twins from the Michigan State University Twin Registry (Study 1: n = 409; Study 2: n = 1,538) in early adolescence, late adolescence, or young adulthood. Disordered eating was assessed with well-validated questionnaires. Finger-length ratios were measured from hand scans, using electronic computer calipers. Findings were consistent across both studies. Higher prenatal testosterone (lower 2D:4D; females from opposite-sex twin pairs vs. controls) predicted lower disordered eating in early adolescence and young adulthood only. Prenatal testosterone-disordered eating associations were not observed during late adolescence. Results point to the possibility of developmental windows of expression for prenatal testosterone's protective effects on disordered eating and suggest that prior discrepant results may reflect age differences across samples.

Timing and tempo: Exploring the complex association between pubertal development and depression in African American and European American girls

The relative contribution of pubertal timing and tempo to the development of depression has not been tested in a large, representative sample, nor has the interface among pubertal maturation, depression, and race been tested. Participants were a community-based sample of 2,450 girls from the Pittsburgh Girls Study who were interviewed annually from ages 9 to 17 years. Pubertal timing and tempo were characterized as a unitary construct and also separately for pubic hair and breast development using child and maternal report. Depression symptoms were assessed annually. African American girls had higher depression symptoms and progressed through puberty earlier, but at a slower tempo than European American girls. Girls with earlier timing had higher levels of depression symptoms at age 10 years. Slower tempo was associated with higher depression symptoms at age 10, and faster tempo was associated with increases in depression from ages 10 to 13. As well, race moderated the associations among timing, tempo, and depression symptoms, and the association between race and depression was partially mediated by pubertal timing and tempo. Pubertal timing and tempo and race contribute to the developmental course of depression from early to late adolescence. The pattern of association varies as a function of the developmental window within which depression is assessed. Thus, repeated measures of depression symptoms and puberty across the span of pubertal development are necessary for exploring the relative importance of dimensions of pubertal development to depression etiology.

Advanced paternal age at birth: phenotypic and etiologic associations with eating pathology in offspring

BACKGROUND

Advanced paternal age at birth has been linked to several psychiatric disorders in offspring (e.g. schizophrenia) and genetic mechanisms are thought to underlie these associations. This study is the first to investigate whether advanced paternal age at birth is associated with eating disorder risk using a twin study design capable of examining both phenotypic and genetic associations.

METHOD

In a large, population-based sample of female twins aged 8-17 years in mid-puberty or beyond (n = 1722), we investigated whether advanced paternal age was positively associated with disordered eating symptoms and an eating disorder history [i.e. anorexia nervosa (AN), bulimia nervosa (BN) or binge eating disorder (BED)] in offspring. Biometric twin models examined whether genetic and/or environmental factors underlie paternal age effects for disordered eating symptoms.

RESULTS

Advanced paternal age was positively associated with disordered eating symptoms and an eating disorder history, where the highest level of pathology was observed in offspring born to fathers ⩾40 years old. The results were not accounted for by maternal age at birth, body mass index (BMI), socio-economic status (SES), fertility treatment or parental psychiatric history. Twin models indicated decreased genetic, and increased environmental, effects on disordered eating with advanced paternal age.

CONCLUSIONS

Advanced paternal age increased risk for the full spectrum of eating pathology, independent of several important covariates. However, contrary to leading hypotheses, environmental rather than genetic factors accounted for paternal age-disordered eating associations. These data highlight the need to explore novel (potentially environmental) mechanisms underlying the effects of advanced paternal age on offspring eating disorder risk.

The emergence of sex differences in risk for disordered eating attitudes during puberty: a role for prenatal testosterone exposure

Research suggests that prenatal testosterone exposure may masculinize (i.e., lower) disordered eating (DE) attitudes and behaviors and influence the lower prevalence of eating disorders in males versus females. How or when these effects become prominent remains unknown, although puberty may be a critical developmental period. In animals, the masculinizing effects of early testosterone exposure become expressed during puberty when gonadal hormones activate sex-typical behaviors, including eating behaviors. This study examined whether the masculinizing effects of prenatal testosterone exposure on DE attitudes emerge during puberty in 394 twins from opposite-sex and same-sex pairs. Twin type (opposite sex vs. same sex) was used as a proxy for level of prenatal testosterone exposure because females from opposite-sex twin pairs are thought to be exposed to testosterone in utero from their male co-twin. Consistent with animal data, there were no differences in levels of DE attitudes between opposite-sex and same-sex twins during pre-early puberty. However, during mid-late puberty, females from opposite-sex twin pairs (i.e., females with a male co-twin) exhibited more masculinized (i.e., lower) DE attitudes than females from same-sex twin pairs (i.e., females with a female co-twin), independent of several "third variables" (e.g., body mass index [BMI], anxiety). Findings suggest that prenatal testosterone exposure may decrease DE attitudes and at least partially underlie sex differences in risk for DE attitudes after mid-puberty.

Differential associations between ovarian hormones and disordered eating symptoms across the menstrual cycle in women

OBJECTIVE

We examined changes in drive for thinness, body dissatisfaction, and dietary restraint across the menstrual cycle and associations between these symptoms and ovarian hormones in two independent samples of women (N = 10 and 8 women, respectively) drawn from the community.

METHOD

Daily self-report measures of disordered eating and negative affect were completed for 35-65 days. Daily saliva samples were assayed for estradiol and progesterone in Study 2 only.

RESULTS

Levels of body dissatisfaction and drive for thinness were highest during the mid-luteal/pre-menstrual phases in both studies and were negatively associated with estradiol, and positively associated with progesterone. By contrast, dietary restraint showed less variation across the menstrual cycle and weaker associations with ovarian hormones.

DISCUSSION

Differential associations between ovarian hormones and specific disordered eating symptoms point to distinct etiological processes within the broader construct of disordered eating.

The effects of puberty on genetic risk for disordered eating: evidence for a sex difference

BACKGROUND

Differences in genetic influences on disordered eating are present across puberty in girls. Heritability is 0% before puberty, but over 50% during and after puberty. Emerging data suggest that these developmental differences may be due to pubertal increases in ovarian hormones. However, a critical piece of evidence is lacking, namely, knowledge of genetic influences on disordered eating across puberty in boys. Boys do not experience increases in ovarian hormones during puberty. Thus, if pubertal increases in genetic effects are present in boys, then factors in addition to ovarian hormones may drive increases in heritability in girls. The current study was the first to examine this possibility in a sample of 1006 male and female twins from the Michigan State University Twin Registry.

METHOD

Disordered eating was assessed with the Minnesota Eating Behavior Survey. Pubertal development was assessed with the Pubertal Development Scale.

RESULTS

No significant differences in genetic influences on disordered eating were observed in males across any developmental stage. Heritability was 51% in boys during pre-puberty, puberty and young adulthood. By contrast, in girls, genetic factors accounted for 0% of the variance in pre-puberty, but 51% of the variance during puberty and beyond. Sex differences in genetic effects were only significant during pre-puberty, as the best-fitting models constrained heritability to be equal across all males, pubertal females and young adult females.

CONCLUSIONS

The results highlight sex-specific effects of puberty on genetic risk for disordered eating and provide indirect evidence of a role for ovarian hormones and/or other female-specific factors.

Binge eating proneness emerges during puberty in female rats: a longitudinal study

Puberty is a critical risk period for binge eating and eating disorders characterized by binge eating. Previous research focused almost entirely on psychosocial risk factors during puberty to the relative exclusion of biological influences. The current study addressed this gap by examining the emergence of binge eating during puberty in a rat model. We predicted that there would be minimal differences in binge eating proneness during pre-early puberty, but significant differences would emerge during puberty. Two independent samples of female Sprague-Dawley rats (n = 30 and n = 36) were followed longitudinally across pre-early puberty, mid-late puberty, and adulthood. Binge eating proneness was defined using the binge eating resistant (BER)/binge eating prone (BEP) model of binge eating that identifies BER and BEP rats in adulthood. Across two samples of rats, binge eating proneness emerged during puberty. Mixed linear models showed little difference in palatable food intake between BER and BEP rats during pre-early puberty, but significant group differences emerged during mid-late puberty and adulthood. Group differences could not be accounted for by changes in nonpalatable food intake or body weight. Similar to patterns in humans, individual differences in binge eating emerge during puberty in female rats. These findings provide strong confirming evidence for the importance of biological risk factors in developmental trajectories of binge eating risk across adolescence.

The effects of ovariectomy on binge eating proneness in adult female rats

Ovarian hormones are associated with binge eating in women, however findings are limited by the lack of experimental control inherent in human studies. Animal research that manipulates ovarian hormone status and examines individual differences in extreme binge eating proneness is needed to model clinical phenotypes in humans and to confirm causal effects. The purpose of this study was to examine the effects of adult ovariectomy on overall binge eating risk and extreme binge eating phenotypes using the binge eating resistant (BER)/binge eating prone (BEP) rat model. We predicted that palatable food consumption would significantly increase after ovariectomy in all rats because ovarian hormones generally suppress food intake. If differences in responsiveness to ovarian hormones underlie BER/BEP phenotypes, then differences in binge eating between BER and BEP rats would be eliminated or diminished after ovariectomy. Changes in palatable food (PF) intake were compared in BER and BEP rats before and after ovariectomy in two samples of adult females. Findings were highly similar in the two samples. PF intake increased significantly following ovariectomy in all rats. However, BEP rats consistently consumed larger amounts of PF than BER rats, both before and after ovariectomy. The consistency of findings across two samples of rats provides strong support for activational effects of ovarian hormones on binge eating. However, the immunity of extreme binge eating phenotypes to ovarian hormone ablation suggests that other, earlier mechanisms (e.g., organizational hormone effects or hormone-independent effects) determine the expression of binge eating phenotypes.

Puberty and the genetic diathesis of disordered eating attitudes and behaviors

Twin studies from the Minnesota Twin Family Study (MTFS) suggest negligible genetic effects on eating pathology before puberty but increased genetic effects during puberty. However, an independent study found no pubertal differences in genetic and environmental effects (R. Rowe, A. Pickles, E. Simonoff, C. M. Bulik, & J. L. Silberg, 2002). Discrepant results may be due to methodological differences. The MTFS studies divided twins at mid-puberty, whereas R. Rowe et al. (2002) divided twins based on menarche alone. In the present study, the authors aimed to reconcile discrepant findings by examining differences in etiologic effects for disordered eating attitudes and behaviors (i.e., levels of weight preoccupation, body dissatisfaction, binge eating, compensatory behaviors) using both classification methods in a new sample of 656 female twins. Using the MTFS method (i.e., K. L. Klump, M. McGue, & W. G. Iacono, 2003), the authors observed nominal genetic effects in prepubertal twins but significant genetic effects in pubertal and young adult twins. Conversely, genetic effects were moderate and equal in all groups using the R. Rowe et al. (2002) method. Findings highlight the potentially important role of puberty in the genetic diathesis of disordered eating attitudes and behaviors and the need to use early indicators of pubertal status in studies of developmental effects.

The influence of gender and puberty on the heritability of disordered eating symptoms

Eating disorders and disordered eating symptoms are clearly heritable, but recent research has suggested that genetic and environmental influences on disordered eating symptoms vary as a function of gender and development. Data are limited, but evidence suggests that gender may moderate the type of genetic risk, rather than the magnitude of genetic effects, on disordered eating symptoms. Only a moderate proportion of the genetic influences on disordered eating symptoms are shared between males and females. In females, at least some of the unique genetic risk may be related to puberty and ovarian hormone regulation. The heritability of disordered eating symptoms in females increases with both pubertal development and increasing levels of estradiol. Although much more research is needed to elucidate specific mechanisms, gonadal hormones may be promising candidates for understanding sex and developmental effects and the ways in which genes exert their influence on disordered eating.

The possible influence of impulsivity and dietary restraint on associations between serotonin genes and binge eating

Although serotonin (5-HT) genes are thought to be involved in the etiology of bulimia nervosa and binge eating, findings from molecular genetic studies are inconclusive. This may be due to limitations of past research, such as a failure to consider the influence of quantitative traits and gene-environment interactions. The current study investigated these issues by examining whether quantitative traits (i.e., impulsivity) and environmental exposure factors (i.e., dietary restraint) moderate 5-HT gene/binge eating associations in a sample of young women (N = 344). Binge eating was assessed using the Minnesota Eating Behavior Survey and the Dutch Eating Behavior Questionnaire (DEBQ). Impulsivity was assessed with the Barratt Impulsiveness Scale-Version 11. Dietary restraint was measured with a factor score derived from common restraint scales. Saliva samples were genotyped for the 5-HT2a receptor T102C polymorphism and 5-HT transporter promoter polymorphism. As expected, impulsivity and dietary restraint were associated with binge eating. Although the T allele of the 5-HT2a receptor gene and the s allele of the 5-HTT gene were associated with higher levels of impulsivity, there were no main effects of 5-HT genotypes on any binge eating measure, and interactions between genotypes, impulsivity, and dietary restraint were non-significant. In conclusion, we found no evidence to suggest that dietary restraint or impulsivity moderate associations between binge eating and these 5-HT genes. Future research should continue to explore interaction effects by examining larger samples, assessing dietary intake directly, and investigating other genes, traits, and environmental factors that may be related to binge eating and bulimia nervosa.

Ovarian hormones and binge eating: exploring associations in community samples

BACKGROUND

Significant associations between changes in ovarian hormones and binge eating are present across the menstrual cycle in women with bulimia nervosa. However, no study has examined these relationships in a non-clinical sample, despite the need for these data for designing risk-factor studies.

METHOD

In study 1, we modified several continuous measures of binge eating and identified those that were most sensitive to menstrual-cycle fluctuations in a non-clinical sample of 10 women who completed measures for 35 days. In study 2, we explored associations between ovarian hormones and binge-eating scores in nine women who completed these same measures for 65 days and provided daily saliva samples for assays of estradiol and progesterone concentrations.

RESULTS

In study 1, the Emotional Eating subscale of the Dutch Eating Behavior Questionnaire exhibited superior reliability and was most sensitive to predicted menstrual-cycle changes in binge eating (i.e. increased scores in the mid-luteal/premenstrual compared with follicular/ovulatory phases). In study 2, this scale showed predicted inverse associations with estradiol and positive associations with progesterone across the menstrual cycle that could not be accounted for by changes in negative affect.

CONCLUSION

Associations between ovarian hormones and binge eating are robust and present in clinical and non-clinical samples. Findings support the ability to examine the role of ovarian hormones as risk factors for binge eating in large-scale prospective studies and twin studies.

Prenatal hormone exposure and risk for eating disorders: a comparison of opposite-sex and same-sex twins

CONTEXT

Although the sex difference in eating disorder prevalence has typically been attributed to psychosocial factors, biological factors may also play a role. Prenatal testosterone exposure is a promising candidate, since it masculinizes behavior in animals and humans via its permanent effects on the central nervous system.

OBJECTIVE

To examine whether in utero testosterone exposure has masculinizing effects on disordered eating (DE) by comparing opposite-sex (OS) and same-sex (SS) twins. Twin type (SS vs OS) is considered a proxy measure of prenatal hormone exposure, since females from OS pairs are exposed to more testosterone in utero than females from SS pairs. A linear trend in mean levels of DE was predicted based on expected prenatal testosterone exposure, with SS female twins exhibiting the highest levels of DE followed by OS female twins, OS male twins, and SS male twins.

DESIGN

A twin study comparison of OS vs SS twins.

SETTING

Michigan State University Twin Registry.

PARTICIPANTS

Participants included 304 SS female twins, 59 OS female twins, 54 OS male twins, and 165 SS male twins.

MAIN OUTCOME MEASURE

Overall levels of DE were assessed with the Minnesota Eating Behavior Survey.

RESULTS

Confirming hypotheses, DE exhibited significant linear trends, with SS female twins exhibiting the highest levels of DE followed by OS female twins, OS male twins, and SS male twins. This linear trend could not be accounted for by levels of anxiety or socialization effects. Indeed, OS female twins exhibited lower levels of DE compared with an independent sample of undergraduate women (n = 69) who were raised with 1 or more brothers.

CONCLUSIONS

The masculinization of DE in OS female twins is unlikely to be due to socialization effects alone. Biological factors, such as the masculinization of the central nervous system by prenatal testosterone exposure, may also contribute to sex differences in DE prevalence.

An association of early puberty with disordered eating and anxiety in a population of undergraduate women and men

Eating and anxiety disorders are more prevalent in females, increase during adolescence, and are associated with early pubertal development. This study examined whether timing of puberty onset is associated with disordered eating and anxiety in a large sample of postpubertal male and female undergraduate students. Self-report questionnaires assessed timing of puberty, disordered eating, anxiety, alcohol use, personality, and sensation seeking. Females scored significantly higher on measures of disordered eating (binge eating, dietary restraint, eating concerns, and weight and shape concerns) and anxiety (state and trait anxiety) than did males. In addition, early maturing women and men scored significantly higher on measures of disordered eating and anxiety than on time or late maturing women and men. Measures of alcohol use, sensation seeking, and personality characteristics differed in males and females but did not vary with pubertal timing. Findings suggest that early puberty is associated with disordered eating and anxiety, and this association may be due to an organizational effect of pubertal hormones. Despite important differences in body fat composition, both males and females experiencing early puberty had an increased incidence of disordered eating. The fact that early puberty was associated with increased eating and anxiety symptoms in both sexes suggests that puberty may influence these symptoms through both biological and psychosocial mechanisms.

Impulsivity as an underlying factor in the relationship between disordered eating and sexual behavior

OBJECTIVE

Previous research has reported associations between bulimia nervosa (BN), increased sexual activity, and impulsivity. However, most studies have examined these topics separately and have not examined the role of impulsivity in associations between bulimic and sexual behaviors. The current study sought to examine relationships between disordered eating, sexual behaviors, and impulsivity, as well as to investigate impulsivity as a third variable in these relationships.

METHOD

The participants were 500 female undergraduate students from a large midwestern university who completed self-report questionnaires of binge eating, the use of compensatory behavior, sexual behavior, and impulsivity.

RESULTS

Compensatory behavior, but not binge eating, was significantly correlated with sexual experiences. Partial correlations indicated that impulsivity is a third variable that partially underlies this relationship.

CONCLUSION

Compensatory behaviors and increased sexual activity likely represent risky behaviors that are influenced by impulsivity levels.