Twin studies of eating disorders: a review

Anorexia Nervosa in Juvenile Systemic Lupus Erythematosus (SLE): A Causality Dilemma

Juvenile-onset systemic lupus erythematosus (jSLE) is an autoimmune disorder with multifaceted clinical findings in different organ systems. Neuropsychiatric manifestations affect more than half of SLE patients, and there is increasing evidence that anorexia nervosa (AN), a feeding and eating disorder (FED) characterized by significantly reduced energy intake, is among them. Herein, a review of the literature on the potential association between jSLE and AN was performed. Reported clinical cases were identified, and putative pathophysiological mechanisms were sought that could potentially explain the observed relationship between these two pathological entities. Four reports of isolated cases and a case series including seven patients were identified. In this limited patient pool, the diagnosis of AN preceded that of SLE in the majority of cases, whereas in all cases both entities were diagnosed within a time span of two years. Many explanations for the observed relationships have been proposed. AN has been associated with the stress of chronic disease diagnosis; on the other hand, the chronic inflammation associated with AN may contribute to the development/appearance of SLE. Adverse childhood experiences, concentrations of leptin, shared autoantibodies, and genetic traits appear to be important factors in this well-established interplay. In essence, it seems important to increase clinician awareness of the concomitant development of AN and SLE and invite further research on the subject.

Hooked on weight control: An economic theory of anorexia nervosa and its impact on health and longevity

In this paper, I integrate a theory of body image, weight control, and addiction in a life cycle model with health deficit accumulation in order to explain the phenomenon of anorexia nervosa and its impact on health and longevity. Individuals consume normal goods and foods and can work off excess calories with physical exercise. There exists a healthy body mass index and deviations from it increasingly cause health deficits due to obesity or underweight. There exists also a subjective target weight and being heavier than target weight causes a loss of utility from body image. Anorexia is initiated in individuals who are particularly successful in weight control and prone to addiction. Addiction to weight control motivates anorexic individuals to perpetually adjust their target weight downwards and to eat less and exercise more. With declining weight, health deficits accumulate faster and mortality risk rises. I calibrate the model to an average American woman with bmi 28. Due to weight loss addiction, the bmi declines to a level of 15 and causes an expected loss of 15 years of life. I also discuss potential therapies and recovery from the disease.

Determining the stability of genome-wide factors in BMI between ages 40 to 69 years

Genome-wide association studies (GWAS) have successfully identified common variants associated with BMI. However, the stability of aggregate genetic variation influencing BMI from midlife and beyond is unknown. By analysing 165,717 men and 193,073 women from the UKBiobank, we performed BMI GWAS on six independent five-year age intervals between 40 and 72 years. We then applied genomic structural equation modeling to test competing hypotheses regarding the stability of genetic effects for BMI. LDSR genetic correlations between BMI assessed between ages 40 to 73 were all very high and ranged 0.89 to 1.00. Genomic structural equation modeling revealed that molecular genetic variance in BMI at each age interval could not be explained by the accumulation of any age-specific genetic influences or autoregressive processes. Instead, a common set of stable genetic influences appears to underpin genome-wide variation in BMI from middle to early old age in men and women alike.

Association Between DRD2 and DRD4 Polymorphisms and Eating Disorders in an Italian Population

Anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED) are the three most common eating disorders (EDs). Their etiopathogenesis is multifactorial where both the environmental and genetic factors contribute to the disease outcome and severity. Several polymorphisms in genes involved in the dopaminergic pathways seem to be relevant in the susceptibility to EDs, but their role has not been fully elucidated yet. In this study, we have analyzed the association between selected common polymorphisms in the DRD2 and DRD4 genes in a large cohort of Italian patients affected by AN (n = 332), BN (n = 122), and BED (n = 132) compared to healthy controls (CTRs) (n = 172). Allelic and genotypic frequencies have been also correlated with the main psychopathological and clinical comorbidities often observed in patients. Our results showed significant associations of the DRD2-rs6277 single nucleotide polymorphism (SNP) with AN and BN, of the DRD4-rs936461 SNP with BN and BED and of DRD4 120-bp tandem repeat (TR) polymorphism (SS plus LS genotypes) with BED susceptibility. Moreover, genotyping of DRD4 48-bp variable number TR (VNTR) identified the presence of ≥7R alleles as risk factors to develop each type of EDs. The study also showed that ED subjects with a history of drugs abuse were characterized by a significantly higher frequency of the DRD4 rs1800955 TT genotype and DRD4 120-bp TR short-allele. Our findings suggest that specific combinations of variants in the DRD2 and DRD4 genes are predisposing factors not only for EDs but also for some psychopathological features often coupled specifically to AN, BN, and BED. Further functional research studies are needed to better clarify the complex role of these proteins and to develop novel therapeutic compounds based on dopamine modulation.

Testing of a model for risk factors for eating disorders and higher weight among emerging adults: Baseline evaluation

Although a range of risk factors have been identified for disordered eating and weight status, the breadth of risk factors have been rarely considered within a single, comprehensive model. The robustness of these findings across countries also remains an open question. The present study sampled 6272 participants aged 18-30 years from eight countries in an attempt to evaluate combined and unique predictors for these two conditions, and to explore possible cross-country differences in these models. Participants completed a range of demographic, biological, behavioral, psychological, and sociocultural measures to test a comprehensive model of the contributions of these predictors for disordered eating and weight-related constructs (binge eating, body mass index, compensatory behaviors, dietary restraint, drive for muscularity, and drive for leanness). Structural invariance testing within a multigroup path analysis framework revealed that a single model across the eight countries provided poor model fit. Freeing of 22% of parameters across countries provided excellent fit and a satisfactory compromise for country-invariant and country-variant parameters in the model. Overall, predictors accounted for between 15% and 60% of variance in the outcome measures, with lowest explained variance for the disordered eating outcomes. Significant unique contributions to prediction were observed for each of the five risk factor variable types and across the eight countries. Thus, the findings show strong support for this model as an explanatory framework of both disordered eating and weight status.

Genetics of eating disorders in the genome-wide era

Enabled by advances in high throughput genomic sequencing and an unprecedented level of global data sharing, molecular genetic research is beginning to unlock the biological basis of eating disorders. This invited review provides an overview of genetic discoveries in eating disorders in the genome-wide era. To date, five genome-wide association studies on eating disorders have been conducted - all on anorexia nervosa (AN). For AN, several risk loci have been detected, and ~11-17% of the heritability has been accounted for by common genetic variants. There is extensive genetic overlap between AN and psychological traits, especially obsessive-compulsive disorder, and intriguingly, with metabolic phenotypes even after adjusting for body mass index (BMI) risk variants. Furthermore, genetic risk variants predisposing to lower BMI may be causal risk factors for AN. Causal genes and biological pathways of eating disorders have yet to be elucidated and will require greater sample sizes and statistical power, and functional follow-up studies. Several studies are underway to recruit individuals with bulimia nervosa and binge-eating disorder to enable further genome-wide studies. Data collections and research labs focused on the genetics of eating disorders have joined together in a global effort with the Psychiatric Genomics Consortium. Molecular genetics research in the genome-wide era is improving knowledge about the biology behind the established heritability of eating disorders. This has the potential to offer new hope for understanding eating disorder etiology and for overcoming the therapeutic challenges that confront the eating disorder field.

Association of 5-HTR2A -1438A/G polymorphism with anorexia nervosa and bulimia nervosa: A meta-analysis

Although a number of studies have been conducted on the association of -1438A/G polymorphism in serotonin 2A receptor (5-HTR2A) gene with anorexia nervosa (AN) and bulimia nervosa (BN), the results remained inconsistent. We thus performed a meta-analysis to clarify the effects of -1438A/G polymorphism on the risk of AN and BN. PubMed, Embase, the Cochrane Library, CNKI, Weipu and Wanfang databases were searched for eligible studies. Pooled odds ratio (OR) and 95 % confidence interval (CI) were calculated to estimate the strength of the association. Subgroup analysis was also performed by ethnicity. In total, 17 studies were included for the meta-analysis, of which 15 studies containing 2028 cases and 2725 controls were used for AN analysis and 7 studies containing 505 cases and 1129 controls for BN analysis. The results showed -1438A/G polymorphism was significantly associated with the risk of AN in four genetic models (allele model, A vs. G: OR = 1.31, 95 % CI = 1.11-1.64, P = 0.003; recessive model, AA vs. GA + GG: OR = 1.69, 95 % CI = 1.28-2.23, P = 0.000; dominant model, AA + GA vs. GG: OR = 1.35, 95 % CI = 1.02-1.79, P = 0.037; co-dominant model, AA vs. GG: OR = 1.94, 95 % CI = 1.29-2.92, P = 0.002) in Caucasians, but not in Asians. We failed to observe a significant association between -1438A/G polymorphism and the risk of BN either in overall or in Caucasian population. The present meta-analysis indicated that A allele and AA genotype of 5-HTR2A -1438A/G polymorphism may contribute to higher risk of AN, especially in Caucasians. However, this polymorphism was not associated with the susceptibility to BN.

Genetic and environmental contributions to diagnostic fluctuation in anorexia nervosa and bulimia nervosa

BACKGROUND

Anorexia nervosa and bulimia nervosa are two severe eating disorders associated with high premature mortality, suicidal risk and serious medical complications. Transition between anorexia nervosa and bulimia nervosa over the illness course and familial co-aggregation of the two eating disorders imply aetiological overlap. However, genetic and environmental liabilities to the overlap are poorly understood. Quantitative genetic research using clinical diagnosis is needed.

METHODS

We acquired a clinical diagnosis of anorexia nervosa (prevalence = 0.90%) and bulimia nervosa (prevalence = 0.48%) in a large population-based sample (N = 782 938) of randomly selected full-sisters and maternal half-sisters born in Sweden between 1970 and 2005. Structural equation modelling was applied to quantify heritability of clinically diagnosed anorexia nervosa and bulimia nervosa and the contributions of genetic and environmental effects on their overlap.

RESULTS

The heritability of clinically diagnosed anorexia nervosa and bulimia nervosa was estimated at 43% [95% confidence interval (CI) (36-50%)] and 41% (31-52%), respectively, in the study population, with the remaining variance explained by variance in unique environmental effects. We found statistically significant genetic [0.66, 95% CI (0.49-0.82)] and unique environmental correlations [0.55 (0.43-0.66)] between the two clinically diagnosed eating disorders; and their overlap was about equally explained by genetic and unique environmental effects [co-heritability 47% (35-58%)].

CONCLUSIONS

Our study supports shared mechanisms for anorexia nervosa and bulimia nervosa and extends the literature from self-reported behavioural measures to clinical diagnosis. The findings encourage future molecular genetic research on both eating disorders and emphasize clinical vigilance for symptom fluctuation between them.

5-HT2AR and BDNF gene variants in eating disorders susceptibility

Evidence from family and twin studies points to a genetic contribution to the etiology of eating disorders (EDs), confirmed by the association of several single nucleotide polymorphisms (SNPs) with this group of disorders. Previous reports have suggested that the serotonin receptor (5-HT2AR) and brain-derived neurotrophic factor (BDNF) genes could be both involved in EDs susceptibility. In order to provide further evidence about such association, we focused our attention on two SNPs located in these genes carrying out a genetic association study on a large Italian cohort composed of 556 ED patients and 355 controls (CTRs). Obtained results confirm the presence of an association between 5-HT2AR and BDNF genes and the susceptibility to EDs.

Associations Between Attention-Deficit/Hyperactivity Disorder and Various Eating Disorders: A Swedish Nationwide Population Study Using Multiple Genetically Informative Approaches

BACKGROUND

Although attention-deficit/hyperactivity disorder (ADHD) and eating disorders (EDs) frequently co-occur, little is known about the shared etiology. In this study, we comprehensively investigated the genetic association between ADHD and various EDs, including anorexia nervosa (AN) and other EDs such as bulimia nervosa.

METHODS

We applied different genetically informative designs to register-based information of a Swedish nationwide population (N = 3,550,118). We first examined the familial coaggregation of clinically diagnosed ADHD and EDs across multiple types of relatives. We then applied quantitative genetic modeling in full-sisters and maternal half-sisters to estimate the genetic correlations between ADHD and EDs. We further tested the associations between ADHD polygenic risk scores and ED symptoms, and between AN polygenic risk scores and ADHD symptoms, in a genotyped population-based sample (N = 13,472).

RESULTS

Increased risk of all types of EDs was found in individuals with ADHD (any ED: odds ratio [OR] = 3.97, 95% confidence interval [CI] = 3.81, 4.14; AN: OR = 2.68, 95% CI = 2.15, 2.86; other EDs: OR = 4.66, 95% CI = 4.47, 4.87; bulimia nervosa: OR = 5.01, 95% CI = 4.63, 5.41) and their relatives compared with individuals without ADHD and their relatives. The magnitude of the associations decreased as the degree of relatedness decreased, suggesting shared familial liability between ADHD and EDs. Quantitative genetic models revealed stronger genetic correlation of ADHD with other EDs (.37, 95% CI = .31, .42) than with AN (.14, 95% CI = .05, .22). ADHD polygenic risk scores correlated positively with ED symptom measures overall and with the subscales Drive for Thinness and Body Dissatisfaction despite small effect sizes.

CONCLUSIONS

We observed stronger genetic association with ADHD for non-AN EDs than for AN, highlighting specific genetic correlation beyond a general genetic factor across psychiatric disorders.

Genetic risk factors for eating disorders: an update and insights into pathophysiology

Genome-wide-association studies (GWASs), epigenetic, gene-expression and gene-gene interaction projects, nutritional genomics and investigations of the gut microbiota have increased our knowledge of the pathophysiology of eating disorders (EDs). However, compared with anorexia nervosa, genetic studies in patients with bulimia nervosa and binge-eating disorder are relatively scarce, with the exception of a few formal genetic and small-sized candidate-gene-association studies. In this article, we review important findings derived from formal and molecular genetics in order to outline a genetics-based pathophysiological model of EDs. This model takes into account environmental and nutritional factors, genetic factors related to the microbiome, the metabolic and endocrine system, the immune system, and the brain, in addition to phenotypical traits of EDs. Shortcomings and advantages of genetic research in EDs are discussed against the historical background, but also in light of potential future treatment options for patients with EDs.

Association of socio-culture factors with disordered eating behavior: An empirical study on urban young girls of West Bengal, India

A shift towards the concept of thin body image is occurring among the urban girls, as an outcome of mass media exposure. A large section of the girls are involved in attaining thin body image which at times develops dissatisfaction over body weight. Body weight dissatisfaction gives rise to the development of body weight concern and disordered eating behavior. The present research aimed to find out the association of socio-cultural factors with disordered eating behavior among a group of urban girls. The study group included 400 girls aged between 14 and 21 years, residing in the city of Howrah, West Bengal, eastern state of India. Information on socio-demographic characteristics, body weight concern, media habits, and family-peer environments was collected using standard pretested questionnaires. A cross-culturally tested questionnaire developed by Srinivasan and colleagues in 1998, was used to measure disordered eating behavior. Bivariate analyses found significant associations between eating behavior and several socio-cultural factors. Multivariate analysis revealed that education level of fathers and birth order of the participants, body weight concern and peers’ influence were the significant predictors of disordered eating behavior of the study participants. Socio-cultural factors have significant associations with the disordered eating behavior of the study participants.

Weighted Gene Co-Expression Network Analysis Reveals Dysregulation of Mitochondrial Oxidative Phosphorylation in Eating Disorders

The underlying mechanisms of eating disorders (EDs) are very complicated and still poorly understood. The pathogenesis of EDs may involve the interplay of multiple genes. To investigate the dysregulated gene pathways in EDs we analyzed gene expression profiling in dorsolateral prefrontal cortex (DLPFC) tissues from 15 EDs cases, including 3 with anorexia nervosa (AN), 7 with bulimia nervosa (BN), 2 AN-BN cases, 3 cases of EDs not otherwise specified, and 102 controls. We further used a weighted gene co-expression network analysis to construct a gene co-expression network and to detect functional modules of highly correlated genes. The functional enrichment analysis of genes in co-expression modules indicated that an altered mitochondrial oxidative phosphorylation process may be involved in the pathogenesis of EDs.

Common adult psychiatric disorders in Swedish primary care where most mental health patients are treated

BACKGROUND

The overall aim of this study is to present descriptive data regarding the treated prevalence of nine common psychiatric and substance use disorders in the first Primary Care Registry (PCR) in Sweden: Major Depression (MD), Anxiety Disorders (AD), Obsessive-Compulsive Disorder (OCD), Adjustment Disorder (AdjD), Eating Disorders (ED), Personality Disorder (PD), Attention Deficit Hyperactivity Disorder (ADHD), Alcohol Use Disorder (AUD) and Drug Abuse (DA).

METHOD

We selected 5,397,675 individuals aged ≥18. We examined patterns of comorbidity among these disorders and explored the association between diagnoses in the PCR and diagnoses obtained from Hospital and Specialist care. We explored the proportion of patients with these nine disorders that are only treated in primary health care.

RESULTS

For four of our disorders, 80% or more of the cases were present only in the PCR: AdjD, DA, AD and MD. For two disorders (OCD and ED), 65-70% of cases were only found in the PCR. For three disorders (PD, AUD, and ADHD), 45-55% of the patients were only present in the PCR.

CONCLUSION

The PCR will, in the future, likely prove to be an important tool for studies in psychiatric epidemiology.

A Comparison of Personality, Life Events, Comorbidity, and Health in Monozygotic Twins Discordant for Anorexia Nervosa

Genetic and environmental factors contribute to the etiology of anorexia nervosa (AN). The co-twin control design is one of the most powerful methods available to evaluate environmental factors that could contribute to differences between monozygotic (MZ) twins who are discordant for AN. Using available data from a unique and rare sample of 22 Swedish female MZ pairs discordant for AN, we compared personality, life events, comorbidity, and health factors. Twins with AN had significantly higher perfectionism scores than unaffected co-twins and reported younger ages at first diet than unaffected co-twins who had dieted. Consistent with previous literature, more twins with AN reported gastrointestinal problems than unaffected co-twins. Although not significant due to low statistical power, more unaffected co-twins reported experiencing emotional neglect than twins with AN. Early dieting may be a harbinger of the development of AN or an early symptom. Higher perfectionism may represent a risk factor, sequela, or both. Sibling perception of neglect is noteworthy given the impact of an ill child with AN on family function and wellbeing. The health and wellbeing of siblings should be addressed clinically when one child in the family suffers from AN.

Common Etiological Sources of Anxiety, Depression, and Somatic Complaints in Adolescents: A Multiple Rater twin Study

Somatic complaints in children and adolescents may be considered part of a broader spectrum of internalizing disorders that include anxiety and depression. Previous research on the topic has focused mainly on the relationship between anxiety and depression without investigating how common somatic symptoms relate to an underlying factor and its etiology. Based on the classical twin design with monozygotic and dizygotic twins reared together, our study aimed to explore the extent to which the covariation between three phenotypes in adolescent girls and boys can be represented by a latent internalizing factor, with a focus on both common and specific etiological sources. A population-based sample of twins aged 12-18 years and their mothers and fathers (N = 1394 families) responded to questionnaire items measuring the three phenotypes. Informants' ratings were collapsed using full information maximum likelihood estimated factor scores. Multivariate genetic analyses were conducted to examine the etiological structure of concurrent symptoms. The best fitting model was an ACE common pathway model without sex limitation and with one substantially heritable (44%) latent factor shared by the phenotypes. Concurrent symptoms also resulted from shared (25%) and non-shared (31%) environments. The factor loaded most on depression symptoms and least on somatic complaints. Trait-specific influences explained 44% of depression variance, 59% of anxiety variance, and 65% of somatic variance. Our results suggest the presence of a general internalizing factor along which somatic complaints and mental distress can be modeled. However, specific influences make the symptom types distinguishable.

Etiology of Eating Disorders in Women

Eating disorders have been studied extensively over the past several decades, yet research of their etiology has lagged behind treatment outcome research. This article reviews the challenges inherent in this research. It illustrates the epidemiologic designs that have been used to test risk factor hypotheses and describes the major studies designed to answer the question of what causes eating disorders. It points to significant gaps in knowledge, chief among them the absence of representative data on prevalence and correlates of eating disorders, and the lack of data regarding eating disorders in ethnic minority populations.

Genetic and environmental contributions to perfectionism and its common factors

The aims of this study: (1) To evaluate the relative contributions of genetics and environment to perfectionism and it's two constructs: self-oriented, and socially prescribed perfectionism. (2) To clarify genetic and environmental common origins of both personal and social components.

METHODS

Participants were 258 pairs of adolescent Spanish twins. Socially prescribed and self-oriented perfectionism were assessed using the perfectionism subscale of the Eating Disorder Inventory.

STATISTICS

univariate and bivariate twin models, according to sex. Results; Heritability of self-oriented perfectionism was 23% in boys and 30% in girls, and of socially prescribed perfectionism 39% in boys and 42% in girls. Bivariate analysis suggested a common genetic and environmental pathway model. The genetic correlation between both perfectionisms was 0.981 in boys and 0.704 in girls. The non-shared environmental correlation was 0.254 in boys and 0.259 in girls. Conclusions; genetic influences on perfectionism are moderate during adolescence. Our results point toward a shared genetic component underlying both kind of perfectionism. These findings generate doubts about the hypothesis of a leading role of genetics in the pathogenesis of Self-oriented perfectionism and of environment in socially prescribed. The high genetic correlation seems to indicate that self-oriented and socially prescribed are the same dimension of perfectionism.

Changes in genetic and environmental influences on disordered eating between early and late adolescence: a longitudinal twin study

BACKGROUND

We investigated the genetic and environmental contributions to disordered eating (DE) between early and late adolescence in order to determine whether different sources of heritability and environmental risk contributed to these peak times of emergence of eating disorders.

METHOD

Adolescent female twins from the Australian Twin Registry were interviewed over the telephone with the Eating Disorder Examination (EDE). Data were collected at 12-15 and 16-19 years (wave 1: N = 699, 351 pairs; wave 3: N = 499, 247 pairs). Assessments also involved self-report measures related to negative life events and weight-related peer teasing.

RESULTS

Unstandardized estimates from the bivariate Cholesky decomposition model showed both genetic influences and non-shared environmental influences increased over adolescence, but shared environmental influences decreased. While non-shared environmental sources active at ages 12-15 years continued to contribute at 16-19 years, new sources of both additive genetic and non-shared environmental risk were introduced at ages 16-19 years. Weight-related peer teasing in early-mid adolescence predicted increases of DE in later adolescence, while negative life events did not.

CONCLUSIONS

Two-thirds of the heritable influence contributing to DE in late adolescence was unique to this age group. During late adolescence independent sources of genetic risk, as well as environmental influences are likely to be related in part to peer teasing, appear key antecedents in growth of DE.

[Genetic and environmental contributions to body mass index in a Spanish adolescent twin sample]

BACKGROUND AND OBJECTIVE

Twin and family studies support large genetic influences on variability in body mass index (BMI), with heritability estimates ranging from 47% to over 90%. Our objective was to study the relative contributions of genetics and environment to BMI, evaluating sex differences, in an adolescent twin sample from Valencia, Spain.

MATERIAL AND METHODS

Five hundred eighty-four pairs of adolescent twins between 13 and 18 years of age completed the study (82 monozygotic [MZ] and 87 dizygotic [DZ] pairs of male twins, 118 MZ and 102 DZ pairs of female twins, and 195 opposite-sex pairs of DZ twins). To determine zygosity, teachers responded a questionnaire on physical similarity. They also measured the participant's height and weight. BMI was calculated and weight status was determined according to age. We used twin models to assess genetic and environmental (common and unique) factors affecting BMI.

RESULTS

There was a 7.1% frequency of overweight and 2.8% of obesity. The estimated heritability of BMI was 88.0% in boys and 72.1% in girls, with the remaining variance attributable to non-shared environment in boys (12.0%) and 8.8% in girls. It was only in girls that common environment had an effect on BMI.

CONCLUSIONS

Genetics appears to play an important role in explaining the variability in BMI in the adolescence, with slight variations between boys and girls. Common environmental factors exert their influence on BMI only in girls.

Genetic and environmental influences on psychological traits and eating attitudes in a sample of Spanish schoolchildren

INTRODUCTION

The heritability of eating disorders has been estimated to range from 22% to over 62%.The aim of this study is to determine the relative influence of genetics and environment that contribute to the drive for thinness, body dissatisfaction, perfectionism, and ineffectiveness, by evaluating sex differences in a sample of adolescent twins from Valencia, Spain.

MATERIAL AND METHODS

Five hundred eighty-four pairs of adolescent twins between 13 and 18 years of age completed the study. To determine zygosity, teachers responded to a questionnaire on physical similarity. Psychological traits of eating disorders were assessed with four sub-scales of the Eating Disorder Inventory (EDI); drive for thinness, body dissatisfaction, perfectionism, and ineffectiveness. Twin models were used to assess genetic and environmental (common and unique) factors affecting these four psychological traits.

RESULTS

All four traits showed significant genetic contributions among girls, with heritability estimates of 37.7% for ineffectiveness, 42.8% for perfectionism, 56.9% for drive for thinness, and 65.5% for body dissatisfaction. Among boys, body dissatisfaction showed no additive genetic contributions, indicating significant shared and individual specific environment effects. The three other traits in boys showed significant additive genetic contributions, but were lower than in girls.

CONCLUSIONS

With the exception of body dissatisfaction in boys, psychological traits of eating disorders show heritability patterns that differ according to sex.

Discussing the putative role of obesity-associated genes in the etiopathogenesis of eating disorders

In addition to the identification of mutations clearly related to Mendelian forms of obesity; genome-wide association studies and follow-up studies have in the last years pinpointed several loci associated with BMI. These genetic alterations are located in or near genes expressed in the hypothalamus that are involved in the regulation of eating behavior. Accordingly, it seems plausible that these SNPs, or others located in related genes, could also help develop aberrant conduct patterns that favor the establishment of eating disorders should other susceptibility factors or personality dimensions be present. However, and somewhat surprisingly, with few exceptions such as BDNF, the great majority of the genes governing these pathways remain untested in patients with anorexia nervosa, bulimia nervosa or binge-eating disorder. In the present work, we review the few existing studies, but also indications and biological concepts that point to these genes in the CNS as good candidates for association studies with eating disorder patients.

Predictive factors of disordered eating and body image satisfaction in cyprus

OBJECTIVE

This study aimed to assess possible relationships and predictor variables between disordered eating attitudes and behaviors, the internalization of the thin ideal construct, body image satisfaction, body image investment, weight-related anxiety, and body mass index (BMI) among Greek-Cypriot female university students in Cyprus.

METHOD

A total of 243 female university students responded to self-report measures assessing disordered eating, internalization of the thin ideal, body satisfaction, body image investment, and weight-related anxiety.

RESULTS

Disordered eating was positively correlated to the internalization of the thin ideal, body image investment, weight-related anxiety, and BMI and negatively correlated with body image satisfaction. The internalization of the thin ideal was also positively correlated to weight-related anxiety and body image investment and negatively correlated to body image satisfaction. Furthermore, weight-related anxiety and internalization of the thin ideal have been found to be significant predictors of disordered eating attitudes.

DISCUSSION

Possible explanations and vulnerability factors are addressed, as well as implication for prevention strategies and future research.

Neuropsychological function in patients with anorexia nervosa or bulimia nervosa

OBJECTIVE

This study explored the neuropsychological performance of patients diagnosed with anorexia nervosa (AN) or bulimia nervosa (BN) compared with healthy controls (HCs). An additional aim was to investigate the effect of several possible mediators on the association between eating disorders (EDs) and cognitive function.

METHOD

Forty patients with AN, 39 patients with BN, and 40 HCs who were comparable in age and education were consecutively recruited to complete a standardized neuropsychological test battery covering the following cognitive domains: verbal learning and memory, visual learning and memory, speed of information processing, visuospatial ability, working memory, executive function, verbal fluency, attention/vigilance, and motor function.

RESULTS

The AN group scored significantly below the HCs on eight of the nine measured cognitive domains. The BN group also showed inferior performance on six cognitive domains. After adjusting for possible mediators, the nadir body mass index (lowest lifetime BMI) and depressive symptoms explained all findings in the BN group. Although this adjustment reduced the difference between the AN and HC groups, the AN group still performed worse than the HCs regarding verbal learning and memory, visual learning and memory, visuospatial ability, working memory, and executive functioning.

DISCUSSION

Patients with EDs scored below the HCs on several cognitive function measures, this difference being most pronounced for the AN group. The nadir BMI and depressive symptoms had strong mediating effects. Longitudinal studies are needed to identify the importance of weight restoration and treatment of depressive symptoms in the prevention of a possible cognitive decline.

Practice parameter for the assessment and treatment of children and adolescents with eating disorders

This Practice Parameter reviews evidence-based practices for the evaluation and treatment of eating disorders in children and adolescents. Where empirical support is limited, clinical consensus opinion is used to supplement systematic data review. The Parameter focuses on the phenomenology of eating disorders, comorbidity of eating disorders with other psychiatric and medical disorders, and treatment in children and adolescents. Because the database related to eating disorders in younger patients is limited, relevant literature drawn from adult studies is included in the discussion.

Weight-for-length trajectories in the first year of life in children of mothers with eating disorders in a large Norwegian Cohort

OBJECTIVE

To describe weight-for-length (WFL) trajectories in the children (birth-12 months) of mothers with and without eating disorders.

METHOD

This study is based on the Norwegian Mother and Child Cohort Study (MoBa) conducted by the Norwegian Institute of Public Health. We categorized women (N = 57,185) based on diagnosis prior to and during pregnancy: anorexia nervosa, bulimia nervosa, eating disorder not otherwise specified-purging subtype, binge eating disorder, or no eating disorder. The primary analysis included a shape invariant model fitted with nonlinear mixed effects to compare growth rates across eating disorder subtypes.

RESULTS

The children of mothers reporting any eating disorder had a lower WFL growth rate from birth to 12 months than the children of mothers without eating disorders, even after adjusting for relative birth weight and some confounders known to affect growth.

DISCUSSION

In this cohort, child WFL was related to maternal eating disorder status before and/or during pregnancy. These differences in growth trajectories warrant further study of long-term health outcomes and, if replicated, tailoring counseling to mothers with eating disorders during pregnancy.

"Not Just Right Experiences" are specific to obsessive-compulsive disorder: further evidence from Italian clinical samples

Not Just Right Experiences (NJREs) are considered to be a perceptually tinged phenomenon mainly related to obsessive-compulsive disorder (OCD). The evidence of an association between NJREs and OCD or OC symptoms have been accumulating in the last few years, whereas there is a paucity of studies about the role of this construct in other clinical conditions considered part of the "OCD spectrum". In the current study, the NJRE-Q-R Severity scale (a well-validated measure of NJREs) was administered to 41 patients with OCD, 53 with hair-pulling disorder (HPD), 38 with gambling disorder (GD) and 43 with eating disorders (ED) along with measures of OC symptoms and general distress. In each group, NJREs were consistently associated with OC symptoms; moreover, the pattern of associations appeared coherent with the main clinical features of each disorder. The OCD group reported higher levels of NJREs severity than GD and ED, whereas there were no differences between the OCD and HPD groups. However, HPD patients did not have higher scores of NJREs severity than GD and ED counterparts. NJREs appear to be specific to OCD, but further study is needed to establish the role of this construct in OCD-related disorders.

Eating Disorders, Pregnancy, and the Postpartum Period: Findings from the Norwegian Mother and Child Cohort Study (MoBa)

This review summarizes studies on eating disorders in pregnancy and the postpartum period that have been conducted as part of the broader Norwegian Mother and Child Cohort Study (MoBa). Prior to the 2000s, empirical literature on eating disorders in pregnancy was sparse and consisted mostly of studies in small clinical samples. MoBa has contributed to a new era of research by making population-based and large-sample research possible. To date, MoBa has led to 19 studies on diverse questions including the prevalence, course, and risk correlates of eating disorders during pregnancy and the postpartum. The associations between eating disorder exposure and pregnancy, birth and obstetric outcomes, and maternal and offspring health and well-being, have also been areas of focus. The findings indicate that eating disorders in pregnancy are relatively common and appear to confer health risks to mother and her child related to sleep, birth outcomes, maternal nutrition, and child feeding and eating.

Intellectual function in patients with anorexia nervosa and bulimia nervosa

OBJECTIVE

This study aimed to examine cognitive function in individuals with anorexia nervosa (AN) and bulimia nervosa (BN) on the basis of IQ measures, indexes and subtests of the Wechsler Adult Intelligence Scale – Third Edition (WAIS-III).

METHODS

A total of 41 patients with AN, 40 patients with BN and 40 healthy controls (HC), matched for sex, age and education, were recruited consecutively to complete the WAIS-III.

RESULTS

The AN group showed a significantly lower performance than the HC group on most global measures and on eight of the 13 administered subtests. Minor differences in verbal function were detected between the BN group and the HC group.

CONCLUSION

The patients with eating disorders showed normal intellectual functions compared with the normative population. However, the AN group displayed a consistently lower performance than the matched HC group, which performed above normative means. The BN group performed at a level between that of the AN and HC groups.

Anorexia nervosa and bulimia nervosa: brains, bones and breeding

Recent research has modified both the conceptualization and treatment of eating disorders. New diagnostic criteria reducing the "not otherwise specified" category should facilitate the early recognition and treatment of anorexia nervosa (AN) and bulimia nervosa (BN). Technology-based studies identify AN and BN as "brain circuit" disorders; epidemiologic studies reveal that the narrow racial, ethnic and income profile of individuals no longer holds true for AN. The major organs affected long term-the brain and skeletal system-both respond to improved nutrition, with maintenance of body weight the best predictor of recovery. Twin studies have revealed gene x environment interactions, including both the external (social) and internal (pubertal) environments of boys and of girls. Family-based treatment has the best evidence base for effectiveness for younger patients. Medication plays a limited role in AN, but a major role in BN. Across diagnoses, the most important medicine is food.

Genetic and environmental causes of variation in adolescent anxiety symptoms: a multiple-rater twin study

Heritability estimates for adolescent anxiety vary across studies, partly depending on who is rating the symptoms. The goal of our study was to estimate genetic and environmental influences using a multi-informant design with responses from a population-based sample of adolescent twins, their mothers and their fathers (N=1394 families). Results from multivariate biometrical modeling indicated quantitative, but no qualitative sex differences in etiology. The best fitting model was an AE Common Pathway model, defining anxiety as a latent factor common to all informants. This model offers error free estimates of genetic and environmental influences explaining the latent factor variance. Variation in the latent factor was highly genetic, with heritability estimates of 65% for boys and 74% for girls. Non-shared environmental effects explained the remaining variance. In addition, there were significant rater-specific genetic and environmental effects for both sexes. The observed rater differences underline the importance of using several informants when studying adolescent anxiety.

A multivariate twin study of the dimensions of religiosity and common psychiatric and substance use disorders

The authors sought to decompose the covariance between seven dimensions of religiosity and two internalizing psychiatric disorders (major depression and phobia) and two externalizing substance use disorders (alcohol dependence and nicotine dependence). Significant negative correlations, accounted for by shared additive genetic effects, were found between alcohol dependence and six of the seven religiosity factors. Additive genetic effects accounted for significant negative correlations between nicotine dependence and one religiosity factor, social religiosity, and between phobia and unvengefulness. Common environmental effects accounted for a significant positive correlation between phobia and the factor God as judge. No statistically significant covariance due to genetic or environmental effects was found for major depression and any of the seven religiosity factors. Overall, although several statistically significant bivariate relationships were found, the estimates of covariance due to additive genetic effects were modest.

Genetic and environmental factors underlying comorbid bulimic behaviours and alcohol use disorders: a moderating role for the dysregulated personality cluster?

Women with bulimia nervosa (BN) frequently have co-occurring alcohol use disorders (AUDs). Studies of shared genetic transmission of these disorders have been mixed. Personality heterogeneity among individuals with BN may explain discrepant findings. Cluster analysis has characterized women with BN in groups on the basis of personality profiles. One group, the Dysregulated cluster, characterized largely by behavioural disinhibition and emotional dysregulation may be more closely linked etiologically to AUDs. This study examined whether genetic associations between BN and AUDs are the strongest among the Dysregulated cluster. Symptoms of BN and AUDs were assessed in female twins at ages 17 and 25 years from the Minnesota Twin Family Study. Personality clusters were defined using the Multidimensional Personality Questionnaire. Twin moderation models suggested small-to-moderate common genetic transmission between BN and AUDs. However, shared genetic effects did not differ by personality cluster. Findings suggest that personality clusters are unlikely to account for inconsistent findings regarding their shared aetiology.

The role of reproductive hormones in the development and maintenance of eating disorders

Much remains to be understood about the etiology of eating disorders. There is substantial evidence that reproductive hormones, specifically estrogens, play a direct role in normal food intake. Evidence is increasing that the reproductive hormones play a role in the abnormal food intake associated with eating disorders. For example, there is an inverse association between estradiol and eating disorder symptoms. Preliminary studies also suggest that hormone augmentation may be a beneficial adjunct to the standard treatment of choice for eating disorders. However, research is limited, so definitive conclusions about the benefit of hormone augmentation in treatment cannot be drawn. Future research, with a focus on translational studies, should continue to explore the role of reproductive hormones in the vulnerability to and maintenance of eating disorders.

Genetics of eating disorders

Disordered eating behavior is the core symptom of the complex disorders anorexia nervosa and bulimia nervosa. Twin and family studies derive high heritability estimates. Hence, substantial genetic influences on the etiology can be assumed for both. Initially, candidate gene studies pertaining to the monoaminergic neurotransmitter systems and to body weight regulation comprised the core of the genetic analyses. Unfortunately, confirmed, solid findings substantiated in meta-analyses are rare, so that eventually none of these associations is unequivocal. Thus, systematic, genome-wide approaches emerged to identify genes with no a priori evidence for their involvement in eating disorders. Genome-wide association studies have hinted to formerly unknown genetic regions. However, significant genome-wide findings have not yet been reported.

The genetics of eating disorders

Over the past decade, considerable advances have been made in understanding genetic influences on eating pathology. Eating disorders aggregate in families, and twin studies reveal that additive genetic factors account for approximately 40% to 60% of liability to anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). Molecular genetics studies have been undertaken to identify alterations in deoxyribonucleic acid sequence and/or gene expression that may be involved in the pathogenesis of disordered eating behaviors, symptoms, and related disorders and to uncover potential genetic variants that may contribute to variability of treatment response. This article provides an in-depth review of the scientific literature on the genetics of AN, BN, and BED including extant studies, emerging hypotheses, future directions, and clinical implications.

Overview of Behavioral Genetics Research for Family Researchers

This article provides an overview of the methods, assumptions, and key findings of behavioral genetics methodology for family researchers with a limited background. We discuss how family researchers can utilize and contribute to the behavioral genetics field, particularly in terms of conducting research that seeks to explain shared environmental effects. This can be done, in part, by theoretically controlling for genetic confounds in research that seeks to determine cause-and-effect relationships among family variables and individual outcomes. Gene-environment correlation and interaction are especially promising areas for the family researcher to address. Given the methodological advancements in the field, we also briefly comment on new methods in molecular genetics for studying psychological mental health disorders.

Set shifting and central coherence as neurocognitive endophenotypes in eating disorders: a preliminary investigation in twins

OBJECTIVES

Weak central coherence and poor set shifting are risk markers for eating disorders that are present post recovery and in first degree relatives. The aim of this study was to examine these traits in twins with eating disorders.

METHODS

Neuropsychological tests were administered to 114 female twins (n = 53 met lifetime DSM-IV eating disorder criteria, n = 19 non-eating disorder cotwins and n = 42 controls). Within pair correlations for monozygotic (MZ) and dizygotic (DZ) twins were calculated and generalised estimating equations (GEE) compared probands, with non-eating disorder cotwins and controls.

RESULTS

The genetic basis was highest for the central coherence tasks (Rey-Osterrieth Complex Figure Task: MZ twins r = 0.44 [CI: 0.07-0.70, P = 0.01] and Group Embedded Figures Test: MZ twins r = 0.58 [CI: 0.26-0.79, P = 0.00]). Poor set shifting was related to obsessive compulsive symptoms in both individuals with eating disorders and their non-eating disorder cotwins (r = 0.2-0.5).

CONCLUSION

Set shifting abilities and central coherence appear to be endophenotypes associated with eating disorders.

Sex differences in the physiology of eating

Hypothalamic-pituitary-gonadal (HPG) axis function fundamentally affects the physiology of eating. We review sex differences in the physiological and pathophysiological controls of amounts eaten in rats, mice, monkeys, and humans. These controls result from interactions among genetic effects, organizational effects of reproductive hormones (i.e., permanent early developmental effects), and activational effects of these hormones (i.e., effects dependent on hormone levels). Male-female sex differences in the physiology of eating involve both organizational and activational effects of androgens and estrogens. An activational effect of estrogens decreases eating 1) during the periovulatory period of the ovarian cycle in rats, mice, monkeys, and women and 2) tonically between puberty and reproductive senescence or ovariectomy in rats and monkeys, sometimes in mice, and possibly in women. Estrogens acting on estrogen receptor-α (ERα) in the caudal medial nucleus of the solitary tract appear to mediate these effects in rats. Androgens, prolactin, and other reproductive hormones also affect eating in rats. Sex differences in eating are mediated by alterations in orosensory capacity and hedonics, gastric mechanoreception, ghrelin, CCK, glucagon-like peptide-1 (GLP-1), glucagon, insulin, amylin, apolipoprotein A-IV, fatty-acid oxidation, and leptin. The control of eating by central neurochemical signaling via serotonin, MSH, neuropeptide Y, Agouti-related peptide (AgRP), melanin-concentrating hormone, and dopamine is modulated by HPG function. Finally, sex differences in the physiology of eating may contribute to human obesity, anorexia nervosa, and binge eating. The variety and physiological importance of what has been learned so far warrant intensifying basic, translational, and clinical research on sex differences in eating.

Common genetic background in anorexia nervosa and obsessive compulsive disorder: preliminary results from an association study

Several lines of evidence, including psychopathological, neurobiological, pharmacological and epidemiological data, supported the association between Anorexia Nervosa (AN) and Obsessive-Compulsive Disorder (OCD). The aim of the present study is to test the hypothesis of partial common genetic background of both disease, AN and OCD. A total of 116 patients with AN, 74 patients with OCD and 91 controls participated in this study. 213 single-nucleotide polymorphisms (SNPs) in 28 candidate genes were analyzed. Five SNPs achieved 0.004 (the nominal p-value expected by chance), 3 with empirical significant p-values (rs10070190 (CDH9) p = 1 × 10(-3), rs4825476 (GRIA3) p = 4 × 10(-4), and rs1074815 (TPH2) p = 8 × 10(-4)) and 2 additional polymorphisms showing nominal significance (rs2834070 (OLIG2) p = 2 × 10(-3) and rs11783752 (SCL18A1) p = 3 × 10(-3)), were found to be related to both AN and OCD. In addition, rs3825885 (NTRK3, p = 9 × 10(-4)) was identified as an AN risk variant, and rs11179027 (TPH2, p = 2 × 10(-3)) as an OCD marker. The ROC analysis confirmed these results and showed interaction among the significant SNPs. The preliminary results we report here reveal a partial common genetic background in AN and OCD, in agreement with previous clinical findings of common symptomathology between these two diseases and open the field of possible treatments for AN. The interaction observed between the associated polymorphisms, could indicate that there is a biological interaction between the serotonin (TPH2 and SLC18A1) and glutamate (GRIA3) pathways and the factors related to neurogenesis (CDH9, OLIG2 and NTRK3) for the explanation of etiopathophysiology in both diseases. However, the results must be replicated in studies with larger cohorts in order to confirm these associations.

Self-efficacy is mainly genetic, not learned: a multiple-rater twin study on the causal structure of general self-efficacy in young people

Social learning theory postulates that self-efficacy is learned through the person's interaction with his/her physical and social environment. In this genetically informative, population-based, multi-informant study of 1,394 adolescent twin pairs, self-efficacy was modeled as one latent psychometric self-efficacy factor with genetic and environmental effects common to all informants, as well as for effects specific for each informant. The results showed that 75% of variation in self-efficacy was due to genetic factors. Non-shared environmental causes explained the remaining 25% of the variance in the latent factor, with no effect of common environment. Some informant-specific effects were also found. The present study challenges the theoretical assumption of learning as the dominant etiological factor behind self-efficacy in young people.

Evaluating new severity dimensions in the DSM-5 for bulimic syndromes using mixture modeling

OBJECTIVE

Proposed DSM-5 severity dimensions reveal ambiguity regarding the extent to which certain features define boundaries between similar diagnoses or represent underlying dimensions within a broader category of bulimic syndromes. The current study utilized a novel mixed modeling approach that can simultaneously model latent dimensions and latent categories to address this ambiguity.

METHOD

Data from structured clinical interviews in 528 adult participants were analyzed.

RESULTS

A three-class solution with one severity dimension that was invariant across groups provided the best-fitting model. Both latent Classes 1 and 2 included bulimic syndromes but were distinguished by greater purging and weight phobia in latent Class 1. Latent Class 3 resembled a noneating disorder class. External validation analyses supported significant differences among empirically derived groups.

DISCUSSION

Weight phobia contributes to categorical distinctiveness among bulimic syndromes whereas other features (purging, binge eating, and weight) may do so only in specific combinations. Uniform severity criteria may be appropriate across bulimic syndromes.

Genetic and environmental influences on thin-ideal internalization

OBJECTIVE

Current research on the etiology of thin-ideal internalization focuses on psychosocial influences (e.g., media exposure). The possibility that genetic influences also account for variance in thin-ideal internalization has never been directly examined. This study used a twin design to estimate genetic effects on thin-ideal internalization and examine if environmental influences are primarily shared or nonshared in origin.

METHOD

Participants were 343 postpubertal female twins (ages: 12-22 years; M = 17.61) from the Michigan State University Twin Registry. Thin-ideal internalization was assessed using the Sociocultural Attitudes toward Appearance Questionnaire-3.

RESULTS

Twin modeling suggested significant additive genetic and nonshared environmental influences on thin-ideal internalization. Shared environmental influences were small and non-significant.

DISCUSSION

Although prior research focused on psychosocial factors, genetic influences on thin-ideal internalization were significant and moderate in magnitude. Research is needed to investigate possible interplay between genetic and nonshared environmental factors in the development of thin-ideal internalization.

A systematic review of obstetric complications as risk factors for eating disorder and a meta-analysis of delivery method and prematurity

OBJECTIVE

The aim of this study was to systematically review the literature on obstetric factors at birth and their role as risk factors for a subsequent eating disorder (ED) and where possible to perform a meta-analysis of case-control studies of EDs and obstetric complications (OCs).

METHOD

Studies were ascertained by computer searches of electronic databases (Medline, PsycINFO, Web of Science and CINAHL), searches of reference lists and from raw data obtained upon request from the authors. A total of 14 studies were identified for the systematic review, of which 6 were eligible for the subsequent meta-analysis. Of the selected 6 studies, 5 reported on the same OCs, namely vaginal instrumental delivery and prematurity. Accordingly, meta-analyses were run on these two variables. Both analyses were conducted on anorexia nervosa (AN) patients.

RESULTS

Findings from the systematic review were conflicting, with some studies reporting a significant relationship between OCs and ED diagnoses and/or ED symptomatology and others refuting it. A non-significant association of instrumental delivery [pooled odds ratio (OR) 1.06, 95%CI: 0.69, 1.65] and prematurity [pooled OR 1.17, 95%CI: 0.91, 1.52] with AN was revealed in our meta-analysis.

CONCLUSION

The current literature on OCs as risk factors for a later ED is contradictory. The range of different occurrences considered as OCs and methodological limitations hinder ultimate conclusions. Upcoming studies should pool datasets together to obtain sufficient power to assess OCs and EDs in combination.

Shared genetic effects between age at menarche and disordered eating

PURPOSE

An early age at menarche is associated with disordered eating in women. However, it is unclear whether they share genetic factors. The goal of the current study was to delineate the genetic correlation between age at menarche and disordered eating.

METHODS

Participants included 427 monozygotic and 329 dizygotic 16-17-year-old female twins from the Swedish Twin Study of Child and Adolescent Development. Disordered eating was assessed with the Eating Disorder Inventory-2. Age at menarche was assessed through self-report. A bivariate correlated factors model was used to delineate the genetic correlation between age at menarche and disordered eating.

RESULTS

The analysis revealed a negative genetic correlation of -.18 in the best-fit model, indicating that the genetic factors that influence younger age at menarche are associated with increased liability for disordered eating.

CONCLUSIONS

Future research should examine possible causes for this correlation, such as the estrogen system and gene-environment interactions.

Nine-year follow-up of girls with anorexia nervosa and their siblings: retrospective perceptions of parental bonding and the influence of illness on their everyday life

BACKGROUND

Few previous anorexia nervosa (AN) studies include siblings.

OBJECTIVE

To investigate if adolescents with AN retrospectively perceived their parents as less caring and more controlling than their siblings, whether perceived parenting was related to psychological problems, and how AN had influenced their everyday lives.

METHOD

Forty-six former patients (mean age 23.1 years) and 21 siblings participated in the study by completing the Parental Bonding Inventory (PBI) and a questionnaire on the influence of AN during the acute phase.

RESULTS

Former patients and their siblings had similar PBI results. Better adaptive functioning and lower levels of internalising psychological problems were correlated with higher ratings of parental care in both patients and siblings. Both patients and siblings reported that the illness had created conflict and caused concern, but had also provided valuable experiences.

CONCLUSION

Perceived parenting was associated with psychological problems in young adulthood but not with eating disorders. Our PBI results for both former patients and siblings were quite similar to non-clinical control groups. Health personnel treating adolescent AN should be aware of siblings' perspectives and needs.

Genetic and environmental causes of variation in perceived loneliness in young people

Loneliness is prevalent in adolescence, despite the widespread expectation directed to young people to start building close relationships beyond the nuclear family. The aim of the present study was to explore the causal genetic and environmental structure behind variability in adolescents' perceived loneliness. Seven national cohorts (ages 12-18 years) of Norwegian twins reared together (1,394 twin pairs) participated. Perceived loneliness was measured with five items from the UCLA Loneliness Scale. Data were collected from mothers, fathers, and twins' self ratings by means of a posted questionnaire. Biometric analyses were applied, testing the causal architecture of loneliness within a psychometric model with one common latent factor in addition to specific genetic and environmental sources influencing the scores of each informant. The results showed a heritability (h(2)) of 75% on the latent perceived loneliness factor, and nonshared environmental effects (e(2)) explaining the remaining 25% of the latent factor variance. There were also significant rater-specific genetic and nonshared environmental effects. No shared environmental effects were found in the model, and there were no sex differences in the estimates. This study showed that variation in perceived loneliness in adolescents is highly genetic. Additional genetic and nonshared environmental etiological sources are to some extent represented in the scores of the specific rater.

Longitudinal stability in genetic effects on children's conversational language productivity

PURPOSE

The authors examined the longitudinal stability of genetic and environmental influences on children's productive language sample measures during the early school-age years.

METHOD

Twin study methodology with structural equation modeling was used to derive univariate estimates of additive genetic (A), shared environmental (C), and nonshared environmental (E) effects on language measures at each of 2 time points, based on 487 twins at the 1st-grade time point and 387 twins at the 2nd-grade time point. To address questions of stability over time, the authors used longitudinal latent factor analysis.

RESULTS

Stability in the Conversational Language factor was accounted for almost entirely by shared genetic effects between 1st and 2nd grade, meaning no new genetic effects were observed at the 2nd time point. In contrast, nonshared environmental effects were entirely time point specific, meaning whatever nonshared environmental influences were operating at the first time point were not influencing individual variation in the language factor at the second time point.

CONCLUSION

The discussion in this article centers on possible candidates for both genetic and nonshared environmental effects as well as implications for clinical practice and future research.