Persistent alterations in behavior and serotonin activity after recovery from anorexia and bulimia nervosa

Epigenetic alterations in patients with anorexia nervosa-a systematic review

Anorexia nervosa (AN) is a complex metabolic and psychological disorder that is influenced by both heritable genetic components and environmental factors. Exposure to various environmental influences can lead to epigenetically induced changes in gene expression. Epigenetic research in AN is still in its infancy, and studies to date are limited in determining clear, valid links to disease onset and progression are limited. Therefore, the aim of this systematic review was to compile and critically evaluate the available results of epigenetic studies specifically in AN and to provide recommendations for future studies. In accordance with the PRISMA guidelines, a systematic literature search was performed in three different databases (PubMed, Embase, and Web of Science) through May 2023. Twenty-three original papers or conference abstracts on epigenetic studies in AN were collected. Epigenome-wide association studies (EWASs), which analyze DNA methylation across the genome in patients with AN and identify potential disease-relevant changes in promoter/regulatory regions of genes, are the most promising for future research. To date, five EWASs on AN have been published, suggesting a potential reversibility of malnutrition-induced epigenetic changes once patients recover. Hence, determining differential DNA methylation levels could serve as a biomarker for disease status or early diagnosis and might be involved in disease progression or chronification. For future research, EWASs with a larger sample size, longitudinal study design and uniform methods should be performed to contribute to the understanding of the pathophysiology of AN, the development of individual interventions and a better prognosis for affected patients.

Prevalence of eating disorders and disordered eating in Western Asia: a systematic review and meta-Analysis

This study aimed to systematically synthesize and appraise existing literature on the prevalence of eating disorders and disordered eating in Western Asia. A systematic literature search of major English and Arabic databases, i.e., PubMed/Medline, EMBASE, PsychInfo, Web of Science and Scopus (English), Al-Manhal (Arabic) and grey literature was done to obtain the prevalence of disordered eating and eating disorders in Western Asia. The literature search was conducted on June 12^th, 2020, and included papers from 1990-2020. Out of the 249 unduplicated original studies reviewed, 27 were included in the final meta-analysis. Data were then categorized according to the tools used to identify the presence of disordered eating or eating disorders. The pooled prevalence of disordered eating as solicited by both the Eating Attitudes Scale 26 and the Eating Attitudes Scale 40 (N = 11841) was 22.07%, the Sick, Control, One stone, Fat, Food Questionnaire (n = 3160) was 22.28% and the Eating Disorder Examination-Questionnaire (n = 425) was 7.95%. The pooled prevalence obtained from those studies using semi-structured interviews for anorexia nervosa (n = 118190) was 1.59%, bulimia nervosa (n = 118513) was 2.41% and the estimated prevalence of Eating Disorder Not Otherwise Specified (EDNOS) (n = 118087) was 3.51%. Although the prevalence rate of eating disorders solicited using semi-structured interviews appeared to parallel the international range, the overall prevalence rate of disordered eating appeared to be slightly higher than the global rates of prevalence. A significant number of the suspected/detected cases of disordered eating appear to fulfill the criteria for EDNOS. This study is classified as evidence obtained from systematic reviews and meta-analyses (i.e. Level 1).

Antipsychotic agents in the treatment of anorexia nervosa: neuropsychopharmacologic rationale and evidence from controlled trials

The search for an effective psychopharmacologic strategy in the treatment of anorexia nervosa (AN) has been elusive for decades and has run the gamut from reserpine to typical antipsychotics, to lithium, to tetrahydrocannabinol, to growth hormone, to anticonvulsants, to antidepressants, to atypical antipsychotics. Only recently has there arisen a potential "diamond in the rough" in the form of the atypical antipsychotic agent, olanzapine, which, in four randomized clinical trials, has shown superiority to placebo (two studies), chlorpromazine (one study), and aripiprazole (one study) in terms of weight gain and/or reduction in obsessional symptoms. The pharmacologic profile of olanzapine and other antipsychotic medications is discussed in light of the known pathophysiology of AN involving serotonin and dopamine systems, as well as brain-derived neurotrophic factor.

Emotional eating in adolescents: a gene (SLC6A4/5-HTT) - depressive feelings interaction analysis

Eating in response to distress--i.e. emotional eating--is highly prevalent in (female) adults with binge eating, but has only a very low prevalence in young children. The present study addresses the emergence of emotional eating in adolescence in relation to depressive feelings. Because a reduction of food intake is considered the biologically natural response to distress, we tested whether the a-typical stress-response of emotional eating develops in interaction with genetic vulnerability. We hypothesized that the short allele of the 5-HTTLPR polymorphism in the serotonin transporter gene, which is associated with lower serotonin activity, would moderate the relation between depressive feelings and the increase in emotional eating, particularly in females. A sample of Dutch families with two adolescents was included in a longitudinal study with a four-year follow-up. A moderator effect of 5-HTTLPR genotype on the relation between depressive feelings and the increase in emotional eating was found in both sexes in the youngest siblings (n = 286). In the older siblings (n = 298), this specific moderator effect was only found in the girls. Younger adolescents and older adolescent girls showed a higher increase in emotional eating if they carried the 5-HTTLPR short allele. This is the first study that found support for a gene × depressive feelings interaction on emergence of emotional eating in (female) adolescents.

The endomorphin system and its evolving neurophysiological role

Endomorphin-1 (Tyr-Pro-Trp-Phe-NH2) and endomorphin-2 (Tyr-Pro-Phe-Phe-NH2) are two endogenous opioid peptides with high affinity and remarkable selectivity for the mu-opioid receptor. The neuroanatomical distribution of endomorphins reflects their potential endogenous role in many major physiological processes, which include perception of pain, responses related to stress, and complex functions such as reward, arousal, and vigilance, as well as autonomic, cognitive, neuroendocrine, and limbic homeostasis. In this review we discuss the biological effects of endomorphin-1 and endomorphin-2 in relation to their distribution in the central and peripheral nervous systems. We describe the relationship between these two mu-opioid receptor-selective peptides and endogenous neurohormones and neurotransmitters. We also evaluate the role of endomorphins from the physiological point of view and report selectively on the most important findings in their pharmacology.

The developmental association between eating disorders symptoms and symptoms of depression and anxiety in juvenile twin girls

OBJECTIVE

We investigated the role of genetic and environmental factors in the developmental association among symptoms of eating disorders, depression, and anxiety syndromes in 8-13-year-old and 14-17-year-old twin girls.

METHODS

Multivariate genetic models were fitted to child-reported longitudinal symptom data gathered from clinical interview on 408 MZ and 198 DZ female twin pairs from the Virginia Twin Study of Adolescent Behavioural Development (VTSABD).

RESULTS

Model-fitting revealed distinct etiological patterns underlying the association among symptoms of eating disorders, depression, overanxious disorder (OAD), and separation anxiety disorder (SAD) during the course of development: 1) a common genetic factor influencing liability to all symptoms - of early and later OAD, depression, SAD, and eating symptoms; 2) a distinct genetic factor specifically indexing liability to early eating disorders symptoms; 3) a shared environmental factor specifically influencing early depression and early eating disorders symptoms; and 4) a common environmental factor affecting liability to symptoms of later eating disorders and both early and later separation anxiety.

CONCLUSIONS

These results suggest a pervasive genetic effect that influences liability to symptoms of over-anxiety, separation anxiety, depression, and eating disorder throughout development, a shared environmental influence on later adolescent eating problems and persistent separation anxiety, genetic influences specific to early eating disorders symptoms, and a shared environmental factor influencing symptoms of early eating and depression.

Gene-gene interaction between the monoamine oxidase A gene and solute carrier family 6 (neurotransmitter transporter, noradrenalin) member 2 gene in anorexia nervosa (restrictive subtype)

We earlier found an association between anorexia nervosa (AN) restrictive subtype (AN-R) and an inserted sequence within the NETpPR, a polymorphic region located in the promoter of the solute carrier family 6 (neurotransmitter transporter, noradrenalin) member 2 (SLC6A2) gene. To further examine the noradrenergic system in AN-R we performed an association study with a functional polymorphism (MAOA-uVNTR) in the promoter of the monoamine oxidase A (MAOA) gene. Since monoamine oxidase A metabolises noradrenalin, a positive association with the MAOA gene would be biologically plausible. The transmission disequilibrium test and 95 trios/duos (AN-R females+biological parents) showed the main effect of the longer, more transcriptionally active form of the MAOA-uVNTR (MAOA-L) to be statistically non-significant (McNemar's chi(2)=1.4, df=1, P=0.238, odds ratio: 1.4, 95% CI 0.8-2.7). A case-control approach supported this finding. We then stratified the MAOA-uVNTR TDT data according to the (a) NETpPR genotype of the AN-R females, and (b) NETpPR allele transmitted from NETpPR-S4/L4 heterozygous mothers. In both cases, contingency table analysis revealed previously unreported gene-gene interaction between the MAOA and SLC6A2 genes (P=0.019 and 0.019, respectively). Receiving an MAOA-L allele more than doubles the risk for developing AN-R, conditional on an individual also being a NETpPR-L4 homozygote (stratum-specific odds ratio: 2.4, 95% CI 1.1-6.0). These results suggest important involvement of the noradrenergic system in the biological underpinnings of AN-R.

Etiologia dos transtornos alimentares: aspectos biológicos, psicológicos e sócio-culturais

Os transtornos alimentares possuem uma etiologia multifatorial, composta de predisposições genéticas, socioculturais e vulnerabilidades biológicas e psicológicas. Entre os fatores predisponentes, destacam-se a história de transtorno alimentar e (ou) transtorno do humor na família, os padrões de interação presentes no ambiente familiar, o contexto sociocultural, caracterizado pela extrema valorização do corpo magro, disfunções no metabolismo das monoaminas centrais e traços de personalidade. A dieta é o comportamento precursor que geralmente antecede a instalação de um transtorno alimentar. Contudo, a presença isolada da dieta não é suficiente para desencadear o transtorno alimentar, tornando-se necessária uma interação entre os fatores de risco e outros eventos precipitantes. Por último, o curso transitório ou crônico de um transtorno alimentar está relacionado à persistência de distorções cognitivas, à ocorrência de eventos vitais significativos e a alterações secundárias ao estado de desnutrição.

The 5-HT(2A) -1438G/A polymorphism in anorexia nervosa: a combined analysis of 316 trios from six European centres

Several case-control association studies have raised the possibility that the A allele of a -1438 G/A polymorphism in the type 2A serotonin receptor (HTR2A) gene may be a risk factor for anorexia nervosa. However the absence of linkage and the existence of negative association studies raise the possibility of false positive findings, resulting from population stratification or lack of statistical power. To address this controversy we recruited a sample of 316 patients with anorexia nervosa from six European centres, and utilised a family-based transmission disequilibrium (TDT) approach to analyse the HTR2A-1438 G/A polymorphism. Age at onset and minimal BMI were also taken into consideration in order to detect clinical heterogeneity or a quantitative trait effect. The TDT approach showed that the A allele was transmitted 133 times and not transmitted 148 times (McNemar chi(2) = 0.29, df = 1, P = 0.59). Also, the haplotype-based haplotype relative risk method showed no evidence for association of the A allele, in samples from each centre (chi(2) < 2.15, df = 1, P > 0.14) and in the total sample (chi(2) = 0.55, df = 1; P = 0.46). Furthermore, we found no evidence for heterogeneity of the A allele frequency between samples (chi(2) = 2.54, df = 4, P = 0.64), either according to minimal-BMI (F1/242 = 2.14, P = 0.45) or age at onset (F1/224 = 2.39; P = 0.12). QTL-TDT analyses also showed no direct role of the A allele on these traits. We thus found no evidence for a significant role of the 5-HT(2A) gene in anorexia nervosa. Previous results may have been exposed to stratification bias (which we controlled by the TDT method) and/or the risk of type 1 error (from which we were less exposed because of the sample size).

The children of mothers with eating disorders

There is good evidence that children of parents with psychological disorders are themselves at increased risk of disturbances in their development. Although there has been considerable research on a variety of disorders such as depression and alcohol, research on the children of parents with eating disorders has been relatively recent. This paper aims to review the evidence and covers a number of areas, including genetic factors, pregnancy, the perinatal and postpartum period, infancy, and the early years of life, focusing on feeding and mealtimes, general parenting functions, and growth. This is followed by a consideration of psychopathology in the children, parental attitudes to children's weight and shape, and adolescence. What is clear is that although there are numerous case reports and case series, the number of systematic controlled studies is relatively small, and almost nothing has been written about the children of fathers with eating disorders. What is evident from the available evidence is that children of mothers with eating disorders are at increased risk of disturbance, but that the risk depends on a variety of factors, and that difficulties in the children are far from invariable. The paper concludes by summarizing five broad categories of putative mechanisms, based on the evidence to date, by which eating disturbance in parents can influence child development.

Anorexia nervosa: manifestations and management for the gastroenterologist

Anorexia nervosa is a complex psychiatric disorder with significant morbidity and mortality. It is important for gastroenterologists to be aware of the physiological effects and potential complications of anorexia nervosa, as they are frequently involved in treating patients with this disorder. We review the classic, GI, and neuroendocrinological features of anorexia nervosa. We also discuss gender differences and treatment options in anorexia nervosa. Further studies of GI physiology and pharmacology are needed to determine whether any disturbances may be amenable to therapeutic intervention. Future treatments directed at improving GI sensorimotor function and neurohormonal abnormalities in patients with anorexia nervosa may impact their nutritional rehabilitation and may have important health economic implications as patients avoid hospitalization and are restored to full activities in society. The current team approach, which incorporates psychiatrists, psychologists, nutritionists, pediatricians, internists, and gastroenterologists in the treatment of patients with anorexia nervosa, will continue to be essential.

Modulation of 5-hydroxytryptamine efflux from rat cortical synaptosomes by opioids and nociceptin

The modulation of [(3)H]-5-hydroxytryptamine ([(3)H]-5-HT) efflux from superfused rat cortical synaptosomes by delta, kappa, mu and ORL(1) opioid receptor agonists and antagonists was studied. Spontaneous [(3)H]-5-HT efflux was reduced (20% inhibition) by either 0.5 microM tetrodotoxin or Ca(2+)-omission. Ten mM K(+)-evoked [(3)H]-5-HT overflow was largely Ca(2+)-dependent (90%) and tetrodotoxin-sensitive (50%). The delta receptor agonist, deltorphin-I, failed to modulate the K(+)-evoked neurotransmitter efflux up to 0.3 microM. The kappa and the mu receptor agonists, U-50,488 and endomorphin-1, inhibited K(+)-evoked [(3)H]-5-HT overflow (EC(50)=112 and 7 nM, respectively; E(max)=28 and 29% inhibition, respectively) in a norBinaltorphimine- (0.3 microM) and naloxone- (1 microM) sensitive manner, respectively. None of these agonists significantly affected spontaneous [(3)H]-5-HT efflux. The ORL(1) receptor agonist nociceptin inhibited both spontaneous (EC(50)=67 nM) and K(+)-evoked (EC(50)=13 nM; E(max)=52% inhibition) [(3)H]-5-HT efflux. The effect of NC was insensitive to naloxone (up to 10 microM), but was antagonized by [Nphe(1)]nociceptin(1-13)NH(2) (a novel selective ORL(1) receptor antagonist; pA(2)=6.7) and by naloxone benzoylhydrazone (pA(2)=6.3). The ORL(1) ligand [Phe(1)psi(CH(2)-NH)Gly(2)]nociceptin(1-13)NH(2) also inhibited K(+) stimulated [(3)H]-5-HT overflow (EC(50)=64 nM; E(max)=31% inhibition), but its effect was partially antagonized by 10 microM naloxone. It is concluded that the ORL(1) receptor is the most important presynaptic modulator of neocortical 5-HT release within the opioid receptor family. This suggests that the ORL(1)/nociceptin system may have a powerful role in the control of cerebral 5-HT-mediated biological functions.

Hypothalamic serotonin in control of eating behavior, meal size, and body weight

Serotonin (5-HT) has been implicated in the control of eating behavior and body weight. Stimulants of this monoamine reduce food intake and weight gain and increase energy expenditure, both in animals and in humans. This article reviews evidence that supports a role for hypothalamic serotonergic receptor mechanisms in the mediation of these effects. A variety of studies in rodents indicate that, at low doses, 5-HT or drugs that enhance the release of this neurotransmitter preferentially inhibit the ingestion of carbohydrate, more than fat or protein. This phenomenon is mediated, in part, by 5-HT receptors located in various medial hypothalamic nuclei. A negative feedback loop exists between the consumption of this macronutrient and the turnover of 5-HT in the hypothalamus. That is, carbohydrate ingestion enhances the synthesis and release of hypothalamic 5-HT, which in turn serves to control the size of carbohydrate-rich meals. A model is described that proposes the involvement of circulating hormones and glucose in this feedback process. These hormones, including insulin, corticosterone, and the adipose tissue-derived hormone, leptin, have impact on serotonergic function as well as satiety. This model further suggests that 5-HT exerts its strongest effect on appetite at the start of the natural feeding cycle, when carbohydrate is normally preferred. Clinical studies provide evidence that is consistent with the proposed model and that implicates 5-HT in disturbances of eating and body weight disorders.