Overview of genetic research in anorexia nervosa: The past, the present and the future

Disordered Eating among People with Schizophrenia Spectrum Disorders: A Systematic Review

Disordered eating, or abnormal eating behaviours that do not meet the criteria for an independent eating disorder, have been reported among people with schizophrenia. We aimed to systemati-cally review literature on disordered eating among people with schizophrenia spectrum disorder (SSD). Seven databases were systematically searched for studies that described the prevalence and correlates of disordered eating among patients with SSD from January 1984 to 15 February 2021. Qualitative analysis was performed using the National Institutes of Health scales. Of 5504 records identified, 31 studies involving 471,159 subjects were included in the systematic review. The ma-jority of studies (17) rated fair on qualitative analysis and included more men, and participants in their 30s and 40s, on antipsychotics. The commonest limitations include lack of sample size or power calculations, poor sample description, not using valid tools, or not adjusting for con-founders. The reported rates were 4.4% to 45% for binge eating, 16.1% to 64%, for food craving, 27% to 60.6% for food addiction, and 4% to 30% for night eating. Positive associations were re-ported for binge eating with antipsychotic use and female gender, between food craving and weight gain, between food addiction and increased dietary intake, and between disordered eating and female gender, mood and psychotic symptoms. Reported rates for disordered eating among people with SSD are higher than those in the general population. We will discuss the clinical, treatment and research implications of our findings.

Mental health dished up-the use of iPSC models in neuropsychiatric research

Genetic and molecular mechanisms that play a causal role in mental illnesses are challenging to elucidate, particularly as there is a lack of relevant in vitro and in vivo models. However, the advent of induced pluripotent stem cell (iPSC) technology has provided researchers with a novel toolbox. We conducted a systematic review using the PRISMA statement. A PubMed and Web of Science online search was performed (studies published between 2006–2020) using the following search strategy: hiPSC OR iPSC OR iPS OR stem cells AND schizophrenia disorder OR personality disorder OR antisocial personality disorder OR psychopathy OR bipolar disorder OR major depressive disorder OR obsessive compulsive disorder OR anxiety disorder OR substance use disorder OR alcohol use disorder OR nicotine use disorder OR opioid use disorder OR eating disorder OR anorexia nervosa OR attention-deficit/hyperactivity disorder OR gaming disorder. Using the above search criteria, a total of 3515 studies were found. After screening, a final total of 56 studies were deemed eligible for inclusion in our study. Using iPSC technology, psychiatric disease can be studied in the context of a patient’s own unique genetic background. This has allowed great strides to be made into uncovering the etiology of psychiatric disease, as well as providing a unique paradigm for drug testing. However, there is a lack of data for certain psychiatric disorders and several limitations to present iPSC-based studies, leading us to discuss how this field may progress in the next years to increase its utility in the battle to understand psychiatric disease.

Features of schizophrenia following premorbid eating disorders

OBJECTIVE

Eating disorders (ED) and schizophrenia are frequently comorbid and schizophrenia shares genetic susceptibility with anorexia. Many factors associated with schizophrenia can disrupt eating, but ED can present years before schizophrenia. If premorbid ED distinguishes a particular subtype of schizophrenia, then phenotypic features may differ between schizophrenia cases with and without premorbid ED.

METHOD

This secondary analysis used data from an inpatient schizophrenia research study that comprehensively assessed life course psychiatric disorders (DIGS interview), intelligence (WAIS), global assessments of function (GAF) and assessed symptoms during medication-free and fixed dose neuroleptic phases (PANSS).

RESULTS

Premorbid ED was identified in 27 of the 288 schizophrenia cases (9.4%). This group had more females than the group without premorbid ED (74.1% vs. 30%); premorbid ED was 5-fold more common in female than male cases (χ² (17.9, P < .0001). Only the premorbid ED group had gustatory hallucinations. They also demonstrated significantly more severe psychotic and disorganization symptoms during medication-free and fixed dose treatment phases, despite similar negative symptoms and GAF scores, as other cases. The premorbid ED group had significantly better cognition overall, but relatively lower nonverbal than verbal intelligence.

DISCUSSION

Premorbid ED may define a specific subtype of schizophrenia that is common in females. Their more severe psychotic symptoms and better IQ, despite similarly impaired function and negative symptoms as other cases, suggests a distinct pathophysiology. Premorbid ED should be considered in evaluating risk states for schizophrenia, and as a relevant phenotype for treatment resistant schizophrenia.

Rigor and reproducibility in genetic research on eating disorders

OBJECTIVE

We explored both within-method and between-method rigor and reproducibility in the field of eating disorders genetics.

METHOD

We present critical evaluation and commentary on component methods of genetic research (family studies, twin studies, molecular genetic studies) and discuss both successful and unsuccessful efforts in the field.

RESULTS

Eating disorders genetics has had a number of robust results that converge across component methodologies. Familial aggregation of eating disorders, twin-based heritability estimates of eating disorders, and genome-wide association studies (GWAS) all point toward a substantial role for genetics in eating disorders etiology and support the premise that genes do not act alone. Candidate gene and linkage studies have been less informative historically.

DISCUSSION

The eating disorders field has entered the GWAS era with studies of anorexia nervosa. Continued growth of sample sizes is essential for rigorous discovery of actionable variation. Molecular genetic studies of bulimia nervosa, binge-eating disorder, and other eating disorders are virtually nonexistent and lag seriously behind other major psychiatric disorders. Expanded efforts are necessary to reveal the fundamental biology of eating disorders, inform clinical practice, and deliver new therapeutic targets.

[Anorexia nervosa in males]

Anorexia nervosa in males Abstract. Anorexia nervosa (AN) is a rare disorder in boys and men with limited data and studies available. The recent update of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) will in all likelihood lead to an increase in the prevalence of AN in boys and men. This study aims to give an overview of the existing data in regards to gender differences in epidemiology, etiology, and symptoms of AN. We aim to highlight the differences in AN between the sexes, from a clinical point of view, and underline the need for further research on AN in boys.

Updates on Genome-Wide Association Findings in Eating Disorders and Future Application to Precision Medicine

Heterogeneity, frequent diagnostic fluctuation across presentations, and global concerns with the absence of effective treatments all encourage science that moves the field toward individualized or precision medicine in eating disorders. We review recent advances in psychiatric genetics focusing on genome-wide association studies (GWAS) in eating disorders. Given that the only eating disorder to be the subject of GWAS to date is anorexia nervosa, we review anorexia GWAS and enumerate the prospects and challenges of a genomics-driven approach towards personalized intervention in eating disorders.

Modeling anorexia nervosa: transcriptional insights from human iPSC-derived neurons

Anorexia nervosa (AN) is a complex and multifactorial disorder occurring predominantly in women. Despite having the highest mortality among psychiatric conditions, it still lacks robust and effective treatment. Disorders such as AN are most likely syndromes with multiple genetic contributions, however, genome-wide studies have been underpowered to reveal associations with this uncommon illness. Here, we generated induced pluripotent stem cells (iPSCs) from adolescent females with AN and unaffected controls. These iPSCs were differentiated into neural cultures and subjected to extensive transcriptome analysis. Within a small cohort of patients who presented for treatment, we identified a novel gene that appears to contribute to AN pathophysiology, TACR1 (tachykinin 1 receptor). The participation of tachykinins in a variety of biological processes and their interactions with other neurotransmitters suggest novel mechanisms for how a disrupted tachykinin system might contribute to AN symptoms. Although TACR1 has been associated with psychiatric conditions, especially anxiety disorders, we believe this report is its first association with AN. Moreover, our human iPSC approach is a proof-of-concept that AN can be modeled in vitro with a full human genetic complement, and represents a new tool for understanding the elusive molecular and cellular mechanisms underlying the disease.

Prevention of eating disorders: A systematic review and meta-analysis

OBJECTIVE

To systematically review and quantify the effectiveness of Eating Disorder (ED) prevention interventions.

METHODS

Electronic databases (including the Cochrane Controlled Trial Register, MEDLINE, PsychInfo, EMBASE, and Scopus) were searched for published randomized controlled trials of ED prevention interventions from 2009 to 2015. Trials prior to 2009 were retrieved from prior reviews.

RESULTS

One hundred and twelve articles were included. Fifty-eight percent of trials had high risk of bias. Findings indicated small to moderate effect sizes on reduction of ED risk factors or symptoms which occurred up to three-year post-intervention. For universal prevention, media literacy (ML) interventions significantly reduced shape and weight concerns for both females (-0.69, confidence interval (CI): -1.17 to -0.22) and males (-0.32, 95% CI -0.57 to -0.07). For selective prevention, cognitive dissonance (CD) interventions were superior to control interventions in reducing ED symptoms (-0.32, 95% CI -0.52 to -0.13). Cognitive behavioural therapy (CBT) interventions had the largest effect size (-0.40, 95% CI -0.55 to -0.26) on dieting outcome at 9-month follow-up while the healthy weight intervention reduced ED risk factors and body mass index. No indicated prevention interventions were found to be effective in reducing ED risk factors.

CONCLUSIONS

There are a number of promising preventive interventions for ED risk factors including CD, CBT and ML. Whether these actually lower ED incidence is, however, uncertain. Combined ED and obesity prevention interventions require further research.

Neurobiochemical and psychological factors influencing the eating behaviors and attitudes in anorexia nervosa

The aim of this study was to determine the characteristic features which contribute to inappropriate eating attitudes in people suffering from anorexia nervosa, based on an analysis of recent data. Factors influencing these attitudes have a genetic, neurobiological, biochemical, affective-motivational, cognitive, and behavioral background. Another important issue addressed in the paper is a description of the mechanism leading to continuous dietary restrictions. The altered activity of neurotransmitters modulating patients’ moods after the consumption of food and a disturbed responsiveness to enterohormones enhance affective-motivational and cognitive aspects which, in turn, impede the improvement of eating behaviors. An understanding of the mechanisms behind the factors affecting the maintenance of inappropriate eating attitudes may contribute to greater effectiveness in the treatment of anorexia nervosa.

Epidemiology of eating disorders in Latin America: a systematic review and meta-analysis

PURPOSE OF REVIEW

Eating disorders are currently not considered to be limited to Western culture. We systematically reviewed the existing literature on the prevalence of eating disorders in Latin America.

RECENT FINDINGS

Of 1583 records screened, 17 studies from Argentina, Brazil, Chile, Colombia, Mexico, and Venezuela were included in the analysis. Most studies reported point-prevalence rates and only three studies provided lifetime and 12-month prevalence rates. We found a mean point-prevalence rate of 0.1% for anorexia nervosa, 1.16% for bulimia nervosa, and 3.53% for binge-eating disorder (BED) in the general population. Heterogeneity for bulimia nervosa and BED was large. This meta-analysis indicates that the prevalence of anorexia nervosa seems to be lower, whereas the prevalence of bulimia nervosa and especially of BED seems to be higher in Latin America than in Western countries.

SUMMARY

Our findings show that eating disorders are common mental disorders in Latin America. However, some facets of Latin American culture might be protective for the development of anorexia nervosa and increase the risk for bulimia nervosa and BED. Further studies investigating the epidemiology of eating disorders and their relation to culture in Latin America are needed.

VIDEO ABSTRACT

SPANISH ABSTRACT.

The Role of Psychotropic Medications in the Management of Anorexia Nervosa: Rationale, Evidence and Future Prospects

Anorexia nervosa (AN) is a severe psychiatric disorder without approved medication intervention. Every class of psychoactive medication has been tried to improve treatment outcome; however, randomized controlled trials have been ambiguous at best and across studies have not shown robust improvements in weight gain and recovery. Here we review the available literature on pharmacological interventions since AN came to greater public recognition in the 1960s, including a critical review of why those trials may not have been successful. We further provide a neurobiological background for the disorder and discuss how cognition, learning, and emotion-regulating circuits could become treatment targets in the future. Making every effort to develop effective pharmacological treatment options for AN is imperative as it continues to be a complex psychiatric disorder with high disease burden and mortality.

Physical and Psychological Morbidity in Adolescents With Atypical Anorexia Nervosa

BACKGROUND AND OBJECTIVE

Adolescents with atypical anorexia nervosa (AN) have lost significant weight but are not underweight. This study aimed to describe the physical and psychological morbidity of adolescents diagnosed with atypical AN, and to compare them with underweight adolescents with AN.

METHODS

All first presentations of atypical AN (n = 42) and full-threshold AN (n = 118) to a specialist pediatric eating disorder program between July 2010 and June 2014 were examined. Diagnosis was assessed by using the Eating Disorder Examination and anthropometric measurement. Psychological morbidity measures included eating and weight concerns, bingeing, purging, compulsive exercise, and psychiatric comorbidity.

RESULTS

Compared with AN, more adolescents with atypical AN were premorbidly overweight or obese (71% vs 12%). They had lost more weight (17.6 kg vs 11.0 kg) over a longer period (13.3 vs 10.2 months). There was no significant difference in the frequency of bradycardia (24% vs 33%;) or orthostatic instability (43% vs 38%). We found no evidence of a difference in frequency of psychiatric comorbidities (38% vs 45%) or suicidal ideation (43% vs 39%). Distress related to eating and body image was more severe in atypical AN.

CONCLUSIONS

Atypical AN considerably affects physical and psychological functioning, despite adolescents presenting within or above the normal weight range. There was little evidence that the morbidity of adolescents with atypical AN was any less severe than that of adolescents with full-threshold AN. The findings support the need for vigilance around weight loss in adolescents, regardless of body size.

Contemporary views on the genetics of anorexia nervosa

Anorexia nervosa (AN) is a serious mental illness characterized by severe dietary restriction that leads to high rates of morbidity, chronicity, and mortality. Unfortunately, effective treatment is lacking and few options are available. High rates of familial aggregation and significant heritability suggested that the complex etiology of AN is affected by both genetic and environmental factors. In this paper, we review studies that reported common and rare genetic variation that influence susceptibility of AN through candidate gene studies, genome-wide association studies, and sequencing-based studies. We also discuss gene expression, methylation, imaging genetics, and pharmacogenetics to demonstrate that these studies have collectively advanced our knowledge of how genetic variation contributes to AN susceptibility and clinical course. Lastly, we highlight the importance of gene by environment interactions (G×E) and share our enthusiasm for the use of nutritional genomic approaches to elucidate the interaction among nutrients, metabolic intermediates, and genetic variation in AN. A deeper understanding of how nutrition alters genome stability, how genetic variation influences uptake and metabolism of nutrients, and how response to food components affects disordered eating, will lead to personalized dietary interventions and effective nutraceutical and pharmacological treatments for AN.