Cynthia M. Bulik

Risk factors for eating disorders.

The authors review research on risk factors for eating disorders, restricting their focus to studies in which clear precedence of the hypothesized risk factor over onset of the disorder is established. They illustrate how studies of sociocultural risk factors and biological factors have progressed on parallel tracks and propose that major advances in understanding the etiology of eating disorders require a new generation of studies that integrate these domains. They discuss how more sophisticated and novel conceptualizations of risk and causal processes may inform both nosology and intervention efforts.

Twin studies of eating disorders : A review

OBJECTIVE Twin methodology has been used to delineate etiological factors in many medical disorders and behavioral traits including eating disorders. Although twin studies are powerful tools, their methodology can be arcane and their implications easily misinterpreted. METHOD The goals of this study are to (a) review the theoretical rationale for twin studies; (b) provide a framework for their interpretation and evaluation; (c) review extant twin studies on eating disorders; and (d) explore the implications for understanding etiological issues in eating disorders. DISCUSSION On the basis of this review, it is not possible to draw firm conclusions regarding the precise contribution of genetic and environmental factors to anorexia nervosa. Twin studies confirm that bulimia nervosa is familial and reveal significant contributions of additive genetic effects and of unique environmental factors in liability to bulimia nervosa. The magnitude of the contribution of shared environment is less clear, but in the studies with the greatest statistical power, it appears to be less prominent than additive genetic factors.

Eating disorders and antecedent anxiety disorders: a controlled study

We compared the prevalence and age of onset of adult and childhood anxiety disorders relative to the primary diagnosis in 68 women with anorexia nervosa (AN), 116 women with bulimia nervosa (BN), 56 women with major depression with no eating disorder (MD) and 98 randomly selected controls (RC) in order to determine whether antecedent anxiety disorders are plausible risk factors for AN and BN. Comorbid anxiety disorders were common in all three clinical groups (AN, 60%; BN, 57%; MD, 48%). In 90% of AN women, 94% of BN women and 71 % of MD women, anxiety disorders preceded the current primary condition (P=0.01), although panic disorder tended to develop after the onset of AN, BN or MD. In multivariate logistic regressions, the odds ratios (ORs) for overanxious disorder (OR=13.4) and obsessive‐compulsive disorder (OR=11.8) were significantly elevated for AN. The ORs for overanxious disorder and social phobia were significantly elevated for BN (OROAD,=4.9; ORSP=15.5) and MD (OROAD,=6.1; ORSP=6.4). These data suggest that certain anxiety disorders are non‐specific risk factors for later affective and eating disorders, and others may represent more specific antecedent risk factors.

Relating body mass index to figural stimuli: population-based normative data for Caucasians.

OBJECTIVE: To establish body mass index (BMI) norms for standard figural stimuli using a large Caucasian population-based sample. In addition, we sought to determine the effectiveness of the figural stimuli to identify individuals as obese or thin.DESIGN: All Caucasian twins born in Virginia between 1915 and 1971 were identified by public birth record. In addition, 3347 individual twins responded to a letter published in the newsletter of the American Association of Retired Persons (AARP). All adult twins (aged 18 and over) from both of these sources and their family members were mailed a 16 page ‘Health and Lifestyle’ questionnaire.SUBJECTS: BMI and silhouette data were available on 16 728 females and 11 366 males ranging in age from 18–100.MEASUREMENTS: Self-report information on height-weight, current body size, desired body size and a discrepancy score using standard figural stimuli.RESULTS: Gender- and age-specific norms are presented linking BMI to each of the figural stimuli. Additional norms for desired body size and discrepancy scores are also presented. Receiver operating curves (ROC) indicate that the figural stimuli are effective in classifying individuals as obese or thin.CONCLUSIONS: With the establishment of these norms, the silhouettes used in standard body image assessment can now be linked to BMI. Differences were observed between women and men in terms of desired body size and discrepancy scores, with women preferring smaller sizes. The figural stimuli are a robust technique for classifying individuals as obese or thin.

Academy for eating disorders position paper: Eating disorders are serious mental illnesses

It is the position of the Academy for Eating Disorders (AED) that anorexia nervosa and bulimia nervosa, along with their variants, are biologically based, serious mental illnesses (BBMI) that warrant the same level and breadth of health care coverage as conditions currently categorized in this way (e.g., schizophrenia, bipolar disorder, depression, obsessive-compulsive disorder). As set forth below, we advocate this position unequivocally based on an emerging science that affirms with a reasonable degree of medical and scientific certainty that eating disorders are significantly heritable; influenced by alterations of brain function; significantly impair cognitive function, judgment, and emotional stability; and restrict the life activities of persons afflicted with these illnesses. Accordingly, the denial or restriction of equitable and sufficient treatment necessary to avert serious health consequences and risk of death is untenable and should be vigorously protested. Commentary

Heritability of binge-eating and broadly defined bulimia nervosa

BACKGROUND Using diagnostic information obtained at two different times, we incorporated error of measurement into structural equation twin models to evaluate the contribution of additive genetic, common environmental, and individual-specific environmental factors to the liability to binge-eating and broadly defined bulimia nervosa (BN). We also evaluated the validity of the equal environment assumption (EEA) with reference to these two phenotypes. METHODS We interviewed 1897 female twins (including both members of 854 twin pairs) from a population-based register about their lifetime history of binge-eating and of broadly defined BN twice, approximately 5 years apart. RESULTS The reliabilities of a lifetime history of binge-eating (kappa = .34) and of broadly defined BN (kappa = .28) were low. Based on single interviews, the heritability of binge-eating was estimated to be 50% and broad BN 60%, with the remaining variance attributable to individual-specific environment. Common environmental influences had no effect on liability to either trait. By combining information from two interview waves and thereby incorporating error of measurement into a structural equation model, the estimated heritability of the latent vulnerability to binge-eating (82%) and broadly defined BN (83%) increased substantially. Although there were no violations of the EEA detected for binge-eating, cosocialization influenced twin concordance for broadly defined BN. CONCLUSIONS Lifetime histories of binge-eating and broadly defined BN appear to be highly heritable conditions of low reliability.

A twin study of genetic and environmental influences on tobacco initiation, regular tobacco use and nicotine dependence

BACKGROUND Numerous twin studies have reported significant genetic contributions to the variability of tobacco initiation (TI), while fewer studies have shown similar results for the persistence of smoking behavior, or nicotine dependence (ND). As the development of ND requires regular tobacco use (RTU) which in turn requires TI, a conditional approach is necessary. METHOD We used structural equation modeling of multi-step conditional processes to examine the relationship between genetic and environmental risk factors for TI, RTU and ND. The tobacco variables were assessed by personal interview in female, male and opposite-sex twin pairs from the population-based Virginia Twin Registry. RESULTS The results suggested that the liabilities to TI, RTU and ND were correlated. Over 80 % of the variance in liability to TI and RTU were shared, and a smaller proportion was shared between RTU and ND. The heritabilities were estimated at 75 %, 80 % and 60 % respectively for TI, RTU and ND. The variance specific to liability to RTU was entirely accounted for by additive genetic factors. Only a modest part of the heritability in liability of ND was due to genetic factors specific to ND. Shared environmental factors were not significant. No sex differences were found for the sources of variation or causal paths, but prevalences were significantly greater in males versus females. CONCLUSIONS This study showed significant overlap in the contribution of genetic factors to individual differences in TI, RTU and ND. Furthermore, there was evidence for significant additional genetic factors specific to RTU and ND.

Anorexia Nervosa and Autism Spectrum Disorders: Guided Investigation of Social Cognitive Endophenotypes.

Death by suicide occurs in a disproportionate percentage of individuals with anorexia nervosa (AN), with a standardized mortality ratio indicating a 57-fold greater risk of death from suicide relative to an age-matched cohort. Longitudinal studies indicate impaired social functioning increases risk for fatal outcomes, while social impairment persists following recovery. Study of social cognition in AN may elucidate impaired processes that may influence therapeutic efficacy. Symptoms of autism spectrum disorders (ASD) are overrepresented in those who evidence a chronic course. Relative to that in AN, social information processing in ASD is well characterized and may inform systematic study in AN. This article (a) reviews impaired interpersonal processes in AN, (b) compares the phenotype of AN with that of ASD, (c) highlights deficits of social cognitive disturbance in ASD relative to AN, and (d) proposes a new framework to understand the interaction of individuals with AN with their social context.

Evidence for a Susceptibility Gene for Anorexia Nervosa on Chromosome 1

Eating disorders, such as anorexia nervosa (AN), have a significant genetic component. In the current study, a genomewide linkage analysis of 192 families with at least one affected relative pair with AN and related eating disorders, including bulimia nervosa, was performed, resulting in only modest evidence for linkage, with the highest nonparametric linkage (NPL) score, 1.80, at marker D4S2367 on chromosome 4. Since the reduction of sample heterogeneity would increase power to detect linkage, we performed linkage analysis in a subset (n=37) of families in which at least two affected relatives had diagnoses of restricting AN, a clinically defined subtype of AN characterized by severe limitation of food intake without the presence of binge-eating or purging behavior. When we limited the linkage analysis to this clinically more homogeneous subgroup, the highest multipoint NPL score observed was 3.03, at marker D1S3721 on chromosome 1p. The genotyping of additional markers in this region led to a peak multipoint NPL score of 3.45, thereby providing suggestive evidence for the presence of an AN-susceptibility locus on chromosome 1p.

Temperament and character in women with anorexia nervosa

The present study examined temperament differences among anorexia nervosa (AN) subtypes and community controls, as well as the effect of body weight on personality traits in women with AN. Temperament and Character Inventory (TCI) scores were compared between 146 women with restrictor-type AN (RAN), 117 women with purging-type AN (PAN), 60 women with binge/purge-type AN (BAN), and 827 community control women (CW) obtained from an archival normative database. Women with AN scored significantly higher on harm avoidance and significantly lower on cooperativeness than CW. Subtype analyses revealed that women with RAN and PAN reported the lowest novelty seeking, RAN women the highest persistence and self-directedness, and PAN women the highest harm avoidance. Body mass index had a nominal effect on subgroup differences, suggesting that personality disturbances are independent of body weight. Findings suggest that certain facets of temperament differ markedly between women with AN, regardless of diagnostic subtype, and controls. More subtle temperament and character differences that were independent of body weight emerged that distinguish among subtypes of AN.