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

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.

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.

Editorial: The critical need to assess pubertal development in studies of child and adolescent psychopathology

Nearly all developmental studies of youth psychopathology assess the effects of age on risk factor-youth outcomes, yet very few examine the effects of pubertal development on developmental trajectories. Growing evidence underscores the importance of both stages of puberty (adrenarche and gonadarche) in risk for psychopathology and the need to consider these developmental stages as predictors and moderators of mental health outcomes and trajectories. The purpose of this Editorial is to provide examples of this evidence and highlight gaps in our literature base as well as opportunities for future research.

A comparative study of orthorexia between premenopausal, perimenopausal, and postmenopausal women

PURPOSE

Studies suggested that menopause is a period of vulnerability for disordered eating behaviors, but whether menopause could be linked to orthorexia nervosa (ON) remains unexplored.

METHODS

A sample composed of 709 women aged between 30 and 71 years (mean age = 43.08 years, SD = 9.24) answered self-administered questionnaires assessing ON (Düsseldorfer Orthorexia Skala, DOS), body image, self-esteem, and psychopathological symptoms. The sample included a Premenopause group of 441 women reporting regular menses, a Perimenopause group of 94 women reporting the recent onset of amenorrhea or menstrual irregularities, and a Postmenopause group of 174 women reporting amenorrhea of natural onset for more than 12 months.

RESULTS

Group comparison using analysis of covariance with age as covariate showed that ON scores were statistically higher in the two groups of participants dealing with menopause (Peri- and Postmenopause) when compared with women not yet concerned by menopause (Premenopause). A Kendall's tau-b correlation performed between the menopausal status (Pre, Peri, or Postmenopause) and DOS categories (No ON; At risk of ON; Presence of ON) showed a weak but statistically significant positive correlation between the menopausal group and DOS categories (tau-b = 0.136, p < 0.001). In addition, Fisher's exact tests indicated that the percentages of participants in the "At risk of ON" and "Presence of ON" categories were statistically higher in the Postmenopause group in comparison with the Premenopause group (p < 0.001). Depressive symptoms were statistically higher in the Peri- and Post-groups, while anxiety symptoms were stronger in the Peri-group when compared with the Pre-group.

CONCLUSIONS

This study shows an increase of ON in women concerned with menopause, suggesting the existence of a relationship between menopause and ON. Further studies are necessary to identify factors involved in this association.

LEVEL OF EVIDENCE

Descriptive (cross-sectional) study, level V.

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.

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 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.

Trait negative affect interacts with ovarian hormones to predict risk for emotional eating

Ovarian hormones significantly influence dysregulated eating in females. However, most women do not develop appreciable disordered eating, suggesting that ovarian hormones may not affect all women equally. We examined whether individual differences in trait negative affect (NA) moderate ovarian hormone-dysregulated eating associations in 446 women who provided saliva samples for hormone measurements and ratings of NA and emotional eating daily for 45 consecutive days. Women were at greatest risk for emotional eating when they had high trait NA and experienced a hormonal milieu characterized by low estradiol or high progesterone. While effects were evident in all women, the combination of high trait NA and high progesterone was particularly risky for women with a history of clinically significant binge eating episodes. These findings provide initial evidence that affective and hormonal risk interact to promote emotional eating, and that effects may be amplified in women with clinically significant binge eating.

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.