Eating disorders in adolescents and young adults

Genome-Wide Characterization of Somatic Mutation Patterns in Cloned Dogs Reveals Implications for Neuronal Function, Tumorigenesis, and Aging

Studies on somatic mutations in cloned animals have revealed slight genetic variances between clones and their originals, but have yet to identify the precise effects of these differences within the organism. Somatic mutations contribute to aging and are implicated in tumor development and other age-related diseases. Thus, we compared whole genome sequencing data from an original dog with that of cloned dogs, identifying candidate somatic mutations that were disproportionately located within genes previously implicated in aging. The substitutional signature of cloning-specific somatic mutations mirrored the uniform distribution characteristic of the signature associated with human aging. Further analysis of genes revealed significant enrichment of traits associated with body size as well as the molecular mechanisms underlying neuronal function and tumorigenesis. Overall, the somatic mutations found in cloned dogs may indicate a conserved mechanism driving aging across species and a broad spectrum of pathway alterations.

Using Continuous Glucose Monitoring to Detect and Intervene on Dietary Restriction in Individuals With Binge Eating: The SenseSupport Withdrawal Design Study

BACKGROUND

Dietary restraint is a key factor for maintaining engagement in binge eating among individuals with binge eating disorder (BED) and bulimia nervosa (BN). Reducing dietary restraint is a mechanism of change in cognitive behavioral therapy (CBT) for individuals with BN and BED. However, many individuals who undergo CBT fail to adequately reduce dietary restraint during treatment, perhaps owing to difficulty in using treatment skills (eg, regular eating) to reduce dietary restraint during their daily lives. The SenseSupport system, a novel just-in-time, adaptive intervention (JITAI) system that uses continuous glucose monitoring to detect periods of dietary restraint, may improve CBT to reduce dietary restraint during treatment by providing real-time interventions.

OBJECTIVE

This study aimed to describe the feasibility, acceptability, and initial evaluation of SenseSupport. We presented feasibility, acceptability, target engagement, and initial treatment outcome data from a small trial using an ABAB (A=continuous glucose monitoring data sharing and JITAIs-Off, B=continuous glucose monitoring data sharing and JITAIs-On) design (in which JITAIs were turned on for 2 weeks and then turned off for 2 weeks throughout the treatment).

METHODS

Participants (N=30) were individuals with BED or BN engaging in ≥3 episodes of ≥5 hours without eating per week at baseline. Participants received 12 sessions of CBT and wore continuous glucose monitors to detect eating behaviors and inform the delivery of JITAIs. Participants completed 4 assessments and reported eating disorder behaviors, dietary restraint, and barriers to app use weekly throughout treatment.

RESULTS

Retention was high (25/30, 83% after treatment). However, the rates of continuous glucose monitoring data collection were low (67.4% of expected glucose data were collected), and therapists and participants reported frequent app-related issues. Participants reported that the SenseSupport system was comfortable, minimally disruptive, and easy to use. The only form of dietary restraint that decreased significantly more rapidly during JITAIs-On periods relative to JITAIs-Off periods was the desire for an empty stomach (t₄₃=1.69; P=.049; Cohen d=0.25). There was also a trend toward greater decrease in overall restraint during JITAs-On periods compared with JITAIs-Off periods, but these results were not statistically significant (t₄₃=1.60; P=.06; Cohen d=0.24). There was no significant difference in change in the frequency of binge eating during JITAIs-On periods compared with JITAIs-Off periods (P=.23). Participants demonstrated clinically significant, large decreases in binge eating (t₂₄=10.36; P<.001; Cohen d=2.07), compensatory behaviors (t₂₄=3.40; P=.001; Cohen d=0.68), and global eating pathology (t₂₄=6.25; P<.001; Cohen d=1.25) from pre- to posttreatment.

CONCLUSIONS

This study describes the successful development and implementation of the first intervention system combining passive continuous glucose monitors and JITAIs to augment CBT for binge-spectrum eating disorders. Despite the lower-than-anticipated collection of glucose data, the high acceptability and promising treatment outcomes suggest that the SenseSupport system warrants additional investigation via future, fully powered clinical trials.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04126694; https://clinicaltrials.gov/ct2/show/NCT04126694.

Heart Rate Variability and Laboratory-Based Loss-of-Control Eating in Children and Adolescents

Among youth, greater heart rate (HR) and lesser HR variability (HRV) are precursors to loss-of-control (LOC) eating episodes in the natural environment. However, there are limited data examining whether pre-meal HR and HRV are associated with greater LOC-eating in the laboratory setting. We therefore examined temporal relationships between pre-meal HR, frequency- and time-based metrics of pre-meal HRV, perceived LOC-eating, and energy intake during a meal designed to simulate a LOC-eating episode. Among 209 participants (54.5% female, 12.58 ± 2.72 years, 0.52 ± 1.02 BMIz), 19 reported LOC-eating in the prior month. Perceived LOC-eating during the laboratory meal was not significantly linked to pre-meal HR (p = 0.37), but was positively related to pre-meal HRV (ps = 0.02–0.04). This finding was driven by youth with recent LOC-eating, as these associations were not significant when analyses were run only among participants without recent reported LOC-eating (p = 0.15–0.99). Pre-meal HR and HRV were not significantly related to total energy intake (ps = 0.27–0.81). Additional research is required to determine whether early-stage pediatric LOC-eating is preceded by a healthy pre-meal stress response. Longitudinal studies could help clarify whether this pattern becomes less functional over time among youth who develop recurrent LOC-eating episodes.

Assessing the effects of stress on feeding behaviors in laboratory mice

Stress often affects eating behaviors, increasing caloric intake in some individuals and decreasing it in others. The determinants of feeding responses to stress are unknown, in part because this issue is rarely studied in rodents. We focused our efforts on the novelty-suppressed feeding (NSF) assay, which uses latency to eat as readout of anxiety-like behavior, but rarely assesses feeding per se. We explored how key variables in experimental paradigms - estrous and diurnal cyclicity, age and duration of social isolation, prandial state, diet palatability, and elevated body weight - influence stress-induced anxiety-like behavior and food intake in male and female C57BL/6J mice. Latency to eat in the novel environment is increased in both sexes across most of the conditions tested, while effects on caloric intake are variable. In the common NSF assay (i.e., lean mice in the light cycle), sex-specific effects of the length of social isolation, and not estrous cyclicity, are the main source of variability. Under conditions that are more physiologically relevant for humans (i.e., overweight mice in the active phase), the novel stress now elicits robust hyperphagia in both sexes . This novel model of stress eating can be used to identify underlying neuroendocrine and neuronal substrates. Moreover, these studies can serve as a framework to integrate cross-disciplinary studies of anxiety and feeding related behaviors in rodents.

Vulnerable and Resilient Phenotypes in a Mouse Model of Anorexia Nervosa

BACKGROUND

Increased physical activity is a common feature of anorexia nervosa (AN). Although high activity levels are associated with greater risk of developing AN, particularly when combined with dieting, most individuals who diet and exercise maintain a healthy body weight. It is unclear why some individuals develop AN while most do not. A rodent model of resilience and vulnerability to AN would be valuable to research. Dopamine, which is believed to play a crucial role in AN, regulates both reward and activity and may modulate vulnerability.

METHODS

Adolescent and young adult female C57BL/6N mice were tested in the activity-based anorexia (ABA) model, with an extended period of food restriction in adult mice. ABA was also tested in dopamine transporter knockdown mice and wild-type littermates. Mice that adapted to conditions and maintained a stable body weight were characterized as resilient.

RESULTS

In adults, vulnerable and resilient phenotypes emerged in both the ABA and food-restricted mice without wheels. Vulnerable mice exhibited a pronounced increase in running throughout the light cycle, which dramatically peaked prior to requiring removal from the experiment. Resilient mice exhibited an adaptive decrease in total running, appropriate food anticipatory activity, and increased consumption, thereby achieving stable body weight. Hyperdopaminergia accelerated progression of the vulnerable phenotype.

CONCLUSIONS

Our demonstration of distinct resilient and vulnerable phenotypes in mouse ABA significantly advances the utility of the model for identifying genes and neural substrates mediating AN risk and resilience. Modulation of dopamine may play a central role in the underlying circuit.

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.

Food cravings and loss-of-control eating in youth: Associations with gonadal hormone concentrations

OBJECTIVE

Among youth with overweight, food cravings (FC) are associated with loss-of-control (LOC)-eating, but the impact of sex-associated biological characteristics on this relationship is unknown. We examined whether sex and gonadal hormone concentrations moderated the relationships between FC and LOC-eating severity among healthy boys and girls across the weight strata in natural and laboratory environments.

METHOD

Using ecological momentary assessment (EMA), FC, and LOC-eating severity were reported 3-5 times a day for 2 weeks. In the laboratory, participants reported FC, consumed lunch from a buffet test meal designed to simulate LOC-eating, and rated LOC-eating severity during the meal.

RESULTS

Eighty-seven youth (13.0 ± 2.7 years, 58.6% female, 32.2% with overweight/obesity) participated. EMA measured general and momentary FC were positively associated with LOC-eating severity (ps < .01), with no differences by sex (ps = .21-.93). Estradiol and progesterone significantly moderated the relationships between FC and LOC-eating such that general FC and LOC-eating severity were only positively associated among girls with greater (vs. lower) estradiol (p = .01), and momentary FC and LOC-eating severity were only positively associated among girls with greater (vs. lower) progesterone (p = .01). Boys' testosterone did not significantly moderate the associations between FC and LOC-eating severity (ps = .36-.97). At the test meal, pre-meal FC were positively related to LOC-eating severity (p < .01), without sex or hormonal moderation (ps = .20-.64).

DISCUSSION

FC were related to LOC-eating severity in boys and girls. In the natural environment, gonadal hormones moderated this relationship in girls, but not boys. The mechanisms through which gonadal hormones might affect the relationship between FC and LOC-eating warrant investigation.

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

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

Pubertal Status and Age are Differentially Associated with Inflammatory Biomarkers in Female and Male Adolescents

A better understanding of the maturational correlates of inflammatory activity during adolescence is needed to more appropriately study both normal and abnormal development. Inflammation is the immune system's first response to infection, injury, or psychological stress, and it has been shown to be elevated in individuals with both physical and psychological conditions. This study examined unique associations between (1) pubertal status and inflammatory biomarkers, and (2) age and inflammatory biomarkers, and whether these relationships differed by sex in a diverse sample of 155 adolescents (54.2% female, 45.8% male; M_age = 16.22) from a northeastern city in the US. A more advanced pubertal status was uniquely associated with lower levels of tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8). Chronological age was uniquely associated with lower IL-8 levels. The association between pubertal status and C-reactive protein (CRP) levels differed by sex: more mature females had higher CRP, whereas pubertal status and CRP were not significantly associated in males. These findings highlight an important relation between pubertal development and inflammatory activity during adolescence.

Relationship between unhealthy weight control behaviors and substance use patterns among Korean adolescents: results from the 2017 national youth risk behavior survey

OBJECTIVE

Unhealthy weight control behaviors (UWCBs) can lead to numerous health problems. Adolescents who engage in UWCB are more likely to abuse substances than other adolescents. However, few studies have examined the relationship between UWCB and substance use, despite the fact that their co-occurrence can result in greater morbidity and mortality. The aim of this study was to examine the association between UWCB and substance use patterns among Korean adolescents using nationally representative data.

STUDY DESIGN

This study involved an analysis of statistical data collected from 27,284 adolescent participants (13-18 years old) in the 2017 Korean Youth Risk Behavior Web-based Survey.

METHODS

The Chi-squared test and multiple logistic regression analysis were performed to demonstrate the association between substance use patterns (energy drink intake, alcohol use, cigarette smoking, electronic cigarette use, and drug use) and UWCB (one-food diets, fasting, diet pill use, and purging). All statistical analyses were performed to reflect complex sampling weights.

RESULTS

More female than male adolescents reported to be engaged in any of the following UWCBs: one-food diets (female: 9.6%, male: 4.8%), fasting (female: 11.6%, male: 7.4%), diet pill use (female: 2.9%, male: 1.5%), and purging (female: 4.1%, male: 2.2%). The prevalence of all UWCBs tended to increase as energy drink intake (P < 0.001), cigarette smoking (P < 0.001), and electronic cigarette use (P < 0.001) increased.

CONCLUSIONS

Health professionals who work with adolescents need to be aware of the importance of screening for UWCB, including one-food diets, fasting, diet pill use, and purging, especially as a co-occurrence with substance use.

Diminished quality of life among adolescents with coeliac disease using maladaptive eating behaviours to manage a gluten-free diet: a cross-sectional, mixed-methods study

BACKGROUND

Certain approaches to managing a strict gluten-free diet (GFD) for coeliac disease (CD) may lead to impaired psychosocial well-being, a diminished quality of life (QOL) and disordered eating. The present study aimed to understand adolescents' approaches to managing a GFD and the association with QOL.

METHODS

Thirty adolescents with CD (13-17 years old) following the GFD for at least 1 year completed the Celiac Dietary Adherence Test (CDAT) and QOL survey. Their approaches to GFD management were explored using a semi-structured interview, where key themes were developed using an iterative process, and further analysed using a psychosocial rubric to classify management strategies and QOL. CDAT ratings were compared across groups.

RESULTS

Gluten-free diet management strategies were classified on a four-point scale. Adaptive eating behaviours were characterised by greater flexibility (versus rigidity), trust (versus avoidance), confidence (versus controlling behaviour) and awareness (versus preoccupation) with respect to maintaining a GFD. Approximately half the sample (53.3%) expressed more maladaptive approaches to maintaining a GFD and those who did so were older with lower CD-Specific Pediatric Quality of Life (CDPQOL) scores, mean subscale differences ranging from 15.0 points for Isolation (t = 2.4, P = 0.03, d.f. = 28) to 23.4 points for Limitations (t = 3.0, P = 0.01, d.f. = 28).

CONCLUSIONS

Adolescents with CD who manage a GFD with maladaptive eating behaviours similar to known risk factors for feeding and eating disorders experience diminished QOL. In accordance with CD management recommendations, we recommend ongoing follow-up with gastroenterologists and dietitians and psychosocial support referrals, as needed.

Preliminary evidence of sex differences in behavioral and neural responses to palatable food reward in rats

The female bias in eating disorder prevalence is the largest in all of psychiatry. Binge eating on palatable food (PF) is a core, maladaptive symptom that cuts across all major types of eating disorders and can be studied via animal models. Using an individual differences rat model of binge eating that identifies binge eating prone (BEP) and binge eating resistant (BER) phenotypes, we previously showed that, compared with males, females consume more PF and are more likely to be classified as BEP. One potential explanation for this sex difference is that PF is inherently more rewarding to females, leading to higher rates of binge eating. Here we tested the hypothesis that females have more robust behavioral and neural responses to PF reward than males. Adult male (N=18) and female (N=17) Sprague-Dawley rats were exposed to the Conditioned Place Preference paradigm using PF as the unconditioned stimulus. Select males (N=9) and females (N=9) were video-recorded during three of the PF-paired conditioning sessions to score feeding behavior. Following CPP, 13 male and 12 female rats were exposed to PF just prior to sacrifice to induce expression of the neural activation marker Fos, and Fos expression was quantified in mesocorticolimbic, hypothalamic, and amygdalar circuits. In the CPP paradigm, females displayed a more robust shift in preference for the chamber paired with PF compared with males, and behavioral analyses revealed that average duration of individual feeding bouts during pairing sessions was longer in females than in males. Fos expression was significantly higher in females vs. males in select regions of the mesocorticolimbic reward circuit, with no sex differences in hypothalamic or amygdalar regions. These results provide initial evidence that PF may be more rewarding to females than to males, possibly due to heightened responsiveness of neural substrates that mediate the hedonic and motivational responses to PF, which in part, may underlie sex differences in binge eating proneness.

Developmental Trajectories of Boys' Driven Exercise and Fasting During the Middle School Years

Boys appear to engage in eating disorder behavior, particularly nonpurging compensatory behaviors such as driven exercise and fasting, at higher rates than previously thought. Little is known about the development of these behaviors in adolescent boys. In a sample of 631 non-binge eating and non-purging boys studied once in 5th grade and 6 times over the 3 years of middle school (grades 6 through 8), we found that (a) for some youth, driven exercise and fasting were present from grade 6; (b) different boys progressed along different trajectories of engagement in driven exercise and fasting, with some boys engaging in no driven exercise or fasting (65.8 % and 83.5 %, respectively), some boys engaging in driven exercise and fasting throughout middle school (25.2 % and 16.5 %, respectively), and other boys discontinuing engagement in driven exercise (9 %); (c) 5th grade depression, eating expectancies, and thinness expectancies predicted subsequent trajectory group membership; and (d) boys engaging in driven exercise and fasting in 8th grade remained distressed. Boys' engagement in driven exercise and fasting behavior merits the attention of researchers and clinicians.

Teens and Research

On seeing promising results in a small number of patients, some researchers are conducting trials to determine whether deep brain stimulation (DBS) is an effective treatment for anorexia nervosa (AN). This article asks whether we should open enrollment in trials of DBS for AN to adolescents. Despite concerns about informed consent, parental consent, and unforeseeable psychological sequelae, the article concludes that the risks to anorexic adolescents associated with participation in trials of DBS are reasonable considering the substantial risks of not enrolling teens with AN in research on DBS. The seriousness of AN, its high incidence in teens, and serious shortfalls in the AN treatment literature point to the need for improved, evidence-based treatments for teens with AN. This unmet need generates an obligation on the part of researchers and physicians to promote and conduct research on AN in adolescents.

Developmental trajectories of compensatory exercise and fasting behavior across the middle school years

Compensatory exercise and fasting behavior, in the absence of binge eating and purging, appear to be important eating disorder behaviors that are associated with dysfunction, but little is known about these behaviors in youth. We studied the trajectories of their development in non-binge eating and non-purging girls during early adolescence. Using a longitudinal design, we assessed 564 girls six times over the three years of middle school (grades 6 through 8) and developed trajectories specifying different developmental patterns in relation to the behaviors. Prior to this period, when the girls were in 5th grade (elementary school), we assessed risk factors to predict girls' subsequent trajectory group membership. Compensatory exercise trajectory groups included a non-engagement group, a group that increased in the behavior, and a group that decreased in the behavior. There were two fasting trajectory groups, one consistently engaging in the behavior and the other consistently not. Elementary school levels of depression, eating expectancies, and thinness expectancies predicted subsequent trajectory group membership. Risk for compensatory exercise and fasting should be evaluated as early as in 5th grade. Targeted interventions should focus on girls in late elementary school or middle school, as this appears to be a critical developmental and maintenance period for compensatory exercise and fasting behavior.

Childhood anxiety trajectories and adolescent disordered eating: findings from the NICHD Study of Early Child Care and Youth Development

OBJECTIVE

The goal of the present article was to examine whether childhood anxiety trajectories predict eating psychopathology. We predicted that girls with trajectories of increasing anxiety across childhood would have significantly greater risk of disordered eating in adolescence in comparison to girls with stable or decreasing trajectories of anxiety over childhood.

METHOD

Data were collected as part of the prospective longitudinal NICHD Study of Early Child Care and Youth Development (N = 450 girls). Childhood anxiety was assessed yearly (54 months through 6th grade) via maternal report on the Child Behavior Checklist. Disordered eating behaviors were assessed at age 15 via adolescent self-report on the Eating Attitudes Test (EAT-26). We conducted latent growth mixture modeling to define girls' childhood anxiety trajectories. Maternal sensitivity, maternal postpartum depression, maternal anxiety, and child temperament were included as predictors of trajectory membership.

RESULTS

The best fitting model included three trajectories of childhood anxiety, the low-decreasing class (22.9% of girls), the high-increasing class (35.4%), and the high-decreasing class (41.6%). Mothers with more symptoms of depression and separation anxiety had girls who were significantly more likely to belong to the high-increasing anxiety trajectory. There were no significant differences in adolescent disordered eating for girls across the three childhood anxiety trajectories.

DISCUSSION

Childhood anxiety, as captured by maternal report, may not be the most robust predictor of adolescent disordered eating and may be of limited utility for prevention programs that aim to identify children in the community at greatest risk for disordered eating.

Puberty and the manifestations of loss of control eating in children and adolescents

OBJECTIVE

We investigated the manifestations of pediatric loss of control (LOC) eating at different stages of pubertal development.

METHOD

Participants were a nonclinical sample of 468 youth (8-17 years). Physical examination determined pubertal stage. LOC eating and disordered eating attitudes were assessed with the Eating Disorder Examination. In a randomized crossover design, a subset (n = 244) ate ad libitum from two test meals designed to capture normal and LOC eating.

RESULTS

There were no differences in the prevalence rates or frequency of reported LOC eating episodes across pubertal stages (ps ≥ 0.50). There were, however, puberty by LOC eating interactions in disordered eating attitudes and palatable food consumption (ps ≤ .05), even after adjusting for age and body composition. LOC eating was associated with elevated global disordered eating attitudes, weight concern, and shape concern in post-pubertal youth (ps ≤ .001), but not pre-pubertal youth (ps ≥ .49). In late-puberty, youth with LOC eating consumed less energy from protein (p < .001) and more from carbohydrate (p = .003) and snack-type foods (p = .02) than those without LOC eating, whereas endorsement of LOC eating in pre- or early-to-mid-puberty was not associated with differences in eating behavior (ps ≥ 0.20).

CONCLUSIONS

Findings suggest that puberty may be a critical risk period, when LOC eating behaviors in boys and girls may become accompanied by greater weight and shape concerns and more obesogenic food consumption patterns. Interventions for LOC eating during pre-puberty should be evaluated to determine if they are particularly beneficial for the prevention of exacerbated eating disorder psychopathology and adverse weight outcomes.

Descriptive review: hormonal influences on risk for eating disorder symptoms during puberty and adolescence

OBJECTIVE

Puberty is an important period of risk for the onset of eating pathology in adolescent females. This review focuses on changes in reproductive hormones during puberty as one specific psychopathogenic mechanism.

METHOD

Studies of puberty and eating disorder-related phenotypes were identified using search databases and the reference sections of previous literature.

RESULTS

Correlational studies of adult women and experimental studies of animals provide evidence for the effects of reproductive hormones on eating disorder symptoms. Very few studies of puberty, however, have directly measured or tested the effects of hormonal change in samples of human adolescents. Commonly used measures of pubertal development, such as menarche or self-reported pubertal status, are relatively poor indicators of individual differences in hormones. The extent to which puberty-related hormonal change accounts for elevated risk for disordered eating remains unclear.

DISCUSSION

Future research is necessary to elucidate the specific relations between hormonal change during puberty and risk for disordered eating. In particular, there is a need for longitudinal studies with multivariate measurement of pubertal development, including direct measures of change in reproductive hormones.

Sex differences in binge eating patterns in male and female adult rats

OBJECTIVE

Several efforts are underway to model binge eating in animals in order to advance neurobiological models of risk. However, knowledge of sex differences in these models is currently lacking. The goal of the present study was to examine sex differences in binge eating phenotypes using a well-established rodent model (i.e., the binge eating resistant/binge eating prone model).

METHOD

Thirty male and 30 female adult Sprague-Dawley rats were exposed to feeding tests consisting of intermittent access to palatable food (PF). Rats were then categorized as binge eating prone (BEP) based on the amount and consistency of PF consumption across tests.

RESULTS

Across multiple methods for BEP classification, rates of BEP phenotypes were two to six times higher in female than male rats.

DISCUSSION

Findings provide support for sex differences in rodent models of binge eating and highlight the promise of the BER/BEP model for understanding neurobiological mechanisms underlying sex differences in risk.

Puberty as a critical risk period for eating disorders: a review of human and animal studies

This article is part of a Special Issue "Puberty and Adolescence". Puberty is one of the most frequently discussed risk periods for the development of eating disorders. Prevailing theories propose environmentally mediated sources of risk arising from the psychosocial effects (e.g., increased body dissatisfaction, decreased self-esteem) of pubertal development in girls. However, recent research highlights the potential role of ovarian hormones in phenotypic and genetic risk for eating disorders during puberty. The goal of this paper is to review data from human and animal studies in support of puberty as a critical risk period for eating disorders and evaluate the evidence for hormonal contributions. Data are consistent in suggesting that both pubertal status and pubertal timing significantly impact risk for most eating disorders in girls, such that advanced pubertal development and early pubertal timing are associated with increased rates of eating disorders and their symptoms in both cross-sectional and longitudinal research. Findings in boys have been much less consistent and suggest a smaller role for puberty in risk for eating disorders in boys. Twin and animal studies indicate that at least part of the female-specific risk is due to genetic factors associated with estrogen activation at puberty. In conclusion, data thus far support a role for puberty in risk for eating disorders and highlight the need for additional human and animal studies of hormonal and genetic risk for eating disorders during puberty.

The Michigan State University Twin Registry (MSUTR): an update

The primary aim of the Michigan State University Twin Registry (MSUTR) is on understanding developmental changes in genetic, environmental, and neurobiological influences on internalizing and externalizing disorders, with antisocial behavior and disordered eating representing our particular areas of interest. The MSUTR has two broad components: a large-scale, population-based registry of child, adolescent, and adult twins and their families (current N ~20,000) and a series of more focused and in-depth studies drawn from the registry (current N ~4,000). Participants in the population-based registry complete a family health and demographic questionnaire via mail. Families are then recruited for one or more of the intensive, in-person studies from the population-based registry based on their answers to relevant items in the registry questionnaire. These in-person assessments target a variety of biological, genetic, and environmental phenotypes, including multi-informant measures of psychiatric and behavioral phenotypes, census and neighborhood informant reports of twin neighborhood characteristics, buccal swab and salivary DNA samples, assays of adolescent and adult steroid hormone levels, and/or videotaped interactions of child twin families. This article provides an overview of the MSUTR and describes current and future research directions.

The interactive effects of estrogen and progesterone on changes in emotional eating across the menstrual cycle

Studies suggest that within-person changes in estrogen and progesterone predict changes in binge eating across the menstrual cycle. However, samples have been extremely small (maximum N = 9), and analyses have not examined the interactive effects of hormones that are critical for changes in food intake in animals. The aims of the current study were to examine ovarian hormone interactions in the prediction of within-subject changes in emotional eating in the largest sample of women to date (N = 196). Participants provided daily ratings of emotional eating and saliva samples for hormone measurement for 45 consecutive days. Results confirmed that changes in ovarian hormones predict changes in emotional eating across the menstrual cycle, with a significant estradiol × progesterone interaction. Emotional eating scores were highest during the midluteal phase, when progesterone peaks and estradiol demonstrates a secondary peak. Findings extend previous work by highlighting significant interactions between estrogen and progesterone that explain midluteal increases in emotional eating. Future work should explore mechanisms (e.g., gene-hormone interactions) that contribute to both within- and between-subjects differences in emotional eating.

The Michigan State University Twin Registry (MSUTR): Genetic, Environmental and Neurobiological Influences on Behavior Across Development

The primary aim of the Michigan State University Twin Registry (MSUTR) is to examine developmental differences in genetic, environmental, and neurobiological influences on internalizing and externalizing symptoms, with disordered eating and antisocial behavior representing particular areas of interest. Twin participants span several developmental stages (i.e., childhood, adolescence, and young adulthood). Assessments include comprehensive, multiinformant measures of psychiatric and behavioral phenotypes, buccal swab and salivary DNA samples, assays of adolescent and adult steroid hormone levels (e.g., estradiol, progesterone, testosterone, cortisol), and videotaped parent–child interactions of child and adolescent twin families. To date, we have collected data on over 1000 twins, with additional data collections underway. This article provides an overview of the newly developed MSUTR and describes current and future research directions.

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.

Animal models of eating disorder traits

Eating disorders, such as anorexia and bulimia nervosa, are psychiatric disorders that are likely determined by a complex interaction between genetic variations, developmental processes, and certain life events. Cross-species analysis of traits related to eating disorders may provide a way to functionally and systematically study neurobiological mechanisms underlying these disorders. Interspecies trait genetics may offer opportunities to identify common neurobiological mechanisms underlying eating disorder characteristics relevant to the initiation, progression, and/or maintenance of the disease, such as cognitive rigidity, increased anxiety levels, and behavioral hyperactivity. These can subsequently be tested directly by studying allelic variation in mice and human subjects and by applying methods that can modify gene expression levels in rodent models. Increasing our knowledge about these traits and their underlying neurobiological mechanisms will be relevant to develop new therapies for patients within the heterogeneous eating disorder populations. Novel mouse genetic and phenotyping tools offer a way to study these neurobehavioral traits under controlled environmental and genetic background conditions.

Weight perception, substance use, and disordered eating behaviors: comparing normal weight and overweight high-school students

Disordered eating behaviors and substance use are two risk factors for the development of serious psychopathology and health concerns in adulthood. Despite the negative outcomes associated with these risky behaviors, few studies have examined potential associations between these risk factors as they occur during adolescence. The importance of accurate or inaccurate weight perception among adolescents has received increased interest given documented associations with nutritional beliefs and weight management strategies. This study examined the associations among the perceptions of weight and substance use with disordered eating behaviors among a diverse sample of normal weight and overweight adolescent males and females. Data came from the 2007 National Youth Risk Behavior Survey (YRBS). The sample consisted of 11,103 adolescents (53.4% female; 44% Caucasian, 21% African American; 13% Hispanic; age responses ranged from 12 and under to 18 and over), with 31.5% meeting criteria for being either at-risk for obesity or already obese (i.e., overweight). As hypothesized, overestimation of weight among normal weight adolescents and accurate perceptions of weight among overweight adolescents were associated with higher rates of disordered eating behaviors. In normal weight adolescents, use of all three substances (tobacco, binge drinking, and cocaine) was associated with each disordered eating behavior. In contrast, findings revealed differences for overweight adolescents between the type of substance use and disordered eating behavior. Post hoc analyses revealed that gender moderated some of these relationships among overweight individuals. Implications for the development and implementation of secondary prevention programs aimed at reducing disordered eating behaviors, substance use, and obesity risk among normal and overweight adolescents are considered.

Preliminary evidence that estradiol moderates genetic influences on disordered eating attitudes and behaviors during puberty

BACKGROUND

Puberty moderates genetic influences on disordered eating attitudes and behaviors, with little genetic influence before puberty but large (50%) genetic effects during and after puberty. To date, however, nothing is known about the mechanisms that underlie these effects. Estradiol is a particularly promising candidate, as estrogens become elevated at puberty and regulate gene transcription within neurotransmitter systems important for eating-related phenotypes. The aim of this pilot study was to examine whether estradiol levels moderate genetic influences on disordered eating during puberty.

METHOD

Participants included 198 female twins (ages 10-15 years) from the Michigan State University Twin Registry. Disordered eating attitudes and behaviors were assessed with the total score, weight preoccupation, body dissatisfaction and binge eating/compensatory behavior subscales of the Minnesota Eating Behavior Survey (MEBS). Afternoon saliva samples were assayed for estradiol levels. Moderation of genetic effects was examined by comparing twin correlations in low versus high estradiol groups.

RESULTS

In the low estradiol group, monozygotic (MZ) and dizygotic (DZ) twin correlations for all MEBS scales were similar, suggesting little genetic influence. In the high estradiol group, the MZ twin correlation was more than double the DZ twin correlation, indicating the presence of genetic effects. Findings could not be accounted for by age, body mass index or the physical changes of puberty.

CONCLUSIONS

Estradiol may be one important moderator of genetic effects on disordered eating during puberty. Larger twin studies are needed to replicate this pilot work and quantify the extent of genetic moderation.

Neurobiology of hyperactivity and reward: agreeable restlessness in anorexia nervosa

Restricted food intake is associated with increased physical activity, very likely an evolutionary advantage, initially both functional and rewarding. The hyperactivity of patients with anorexia nervosa, however, is a main problem for recovery. This seemingly paradoxical reward of hyperactivity in anorexia nervosa is one of the main aspects in our framework for the neurobiological changes that may underlie the development of the disorder. Here, we focus on the neurobiological basis of hyperactivity and reward in both animals and humans suggesting that the mesolimbic dopamine and hypothalamic orexin neurons play central roles. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009.

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.

Disordered eating and substance use in high-school students: results from the Youth Risk Behavior Surveillance System

OBJECTIVE

To examine the association between disordered eating (fasting, diet product use, and vomiting or laxative use) and use of 10 substances (cigarettes, alcohol, marijuana, cocaine, inhalants, heroin, methamphetamines, ecstasy, steroids, and hallucinogens) in a nationally representative adolescent sample.

METHOD

Participants were 13,917 U.S. high-school students participating in the 2005 Youth Risk Behavior Surveillance System.

RESULTS

Disordered eating was significantly associated with the use of each substance. Using effect size estimates that take base rates into consideration, for female students, associations between substance use and disordered eating were weak for all but three forms of substance use: current smoking, binge drinking, and inhalants. Among male students, strong (marijuana, steroids, and inhalants) or moderate effects (all other substances) were observed.

CONCLUSION

Future research needs to focus on inhalant use and methamphetamine use in males. Increased medical attention should be directed toward adolescents who practice disordered eating behaviors because they are also at elevated risk for using cigarettes, alcohol, inhalants, methamphetamines, and steroids.

Temporal patterns of recovery across eating disorder subtypes

OBJECTIVE

To compare patterns of recovery in individuals with index episodes of anorexia nervosa (AN) and bulimia nervosa (BN).

METHOD

Using Kaplan-Meier methods and Cox proportional hazards models, comparisons were conducted that were conditional on duration of eating disorder from onset and included a conservative recovery criterion of 3 asymptomatic years. Data collection was retrospective and from two of the international Price Foundation genetic studies on 901 individuals with eating disorders.

RESULTS

Using Kaplan-Meier methods, 11% of those with index AN and 10% of those with index BN met recovery criteria at 10 years. At 15 years, 16% of those with index AN and 25% of those with index BN met recovery criteria. In a Cox proportional hazards model the index BN group had three times the rate of recovery at 10-14 years (p=0.01) than the index AN group.

CONCLUSIONS

Initially the probability of recovery was greater for those with index AN, but as the duration of the eating disorder lengthened those with BN had higher probabilities of recovery. Replication of these results with prospective data using similarly stringent recovery criteria and methods is required to confirm trends.

Inpatients with eating disorders: demographic, diagnostic, and service characteristics from a nationwide pediatric sample

OBJECTIVE

This study describes the demographic and clinical characteristics of youth hospitalized with an eating disorder, using the Pediatric Health Information System (PHIS) database.

METHOD

Descriptive and inferential statistics were used to examine and compare PHIS inpatients (N = 1,713) with a primary discharge diagnosis of anorexia, bulimia, or eating disorder, not otherwise specified.

RESULTS

Of pediatric inpatients with eating disorders, 92% were female and 78% were non-Hispanic white. Their mean age was 15.3 years; 71% had anorexia; 68% had one or more comorbid psychiatric disorders; 53% stayed on a psychiatric unit; the mean length of stay was 15.7 days. Private insurance paid for 55% of hospital stays. Patients without private insurance were more likely than patients with private insurance to be Black or Hispanic and to have comorbid psychiatric diagnoses.

CONCLUSION

This study provides new information that can be used by hospitals to anticipate developmental and treatment needs of future inpatients with eating disorders.

Good outcome of adolescent onset anorexia nervosa after systematic treatment. Intermediate to long-term follow-up of a representative county-sample

We studied the intermediate to long-term outcome of childhood and adolescent onset anorexia nervosa (AN), in a sample that had received systematic treatment based on close cooperation between parents, paediatric department and child and adolescent psychiatry. Of 55 female AN-patients, 51 were examined 3.5-14.5 years after treatment start. The material includes all AN-patients under 18 years in one county that received inpatient treatment and almost all that received outpatient treatment, during the time period 1986-1998. Forty-two (82%) subjects had no eating disorder (ED) at follow-up, one (2%) had AN, one (2%) bulimia nervosa (BN) and seven (14%) had less severe ED (EDNOS). Except the one with BN, none had bulimic symptoms. There was no mortality. Twenty (41%) had one or more other axis-1 psychiatric diagnoses at follow-up. Depression and anxiety disorders were most frequent. Psychosocial functioning assessed by Global Assessment of Functioning (GAF) was fairly good; mean 73+/-SD14 for symptoms and mean 77+/-SD13 for functioning. Only 48% were satisfied with life, compared to 83% in a normal population sample. Our conclusion is that the eating disorder outcome was good. However, in accordance with other studies, many subjects had other psychiatric problems at follow-up.