Examination of the shared genetic basis of anorexia nervosa and obsessive-compulsive disorder

Obsessive-compulsive disorder with compulsive exercise leading to intensive care treatment in an adolescent male: a case report

Obsessive-compulsive disorder (OCD) and eating disorders (ED) are compulsive disorders with overlapping symptoms. However, weight loss and over-exercise causing secondary medical complications are rarely seen in OCD. We report the case of a 15-year-old male who presented with atypical symptoms of OCD leading to severe medical compromise. Covid-19 related team sport restrictions led to compulsive exercise associated with intrusive thoughts. The onset of stress fractures limited exercise ability, prompting compensatory food restriction. Bradycardia, hypothermia and hypoglycaemia resulted from severe malnourishment and weight loss in the context of OCD. His weight was 85.8% of ideal body weight on admission, reflective of a weight 10-15 kg lower than his premorbid weight. During admission, he developed exercise-induced rhabdomyolysis with significantly elevated creatinine kinase and required intensive care unit treatment. Psychotropic medication included lamotrigine, olanzapine and high dose fluoxetine alongside cognitive-behavioural therapy. Medical stabilisation and weight restoration allowed discharge to an outpatient Child and Adolescent Mental Health Service. This atypical case of OCD highlights the potentially life-threatening risks associated with excessive exercise and malnutrition. This paper highlights the complexities of treatment in a patient who cannot adhere to bed rest and the differential diagnoses of anorexia nervosa, orthorexia nervosa and exercise addiction.

Association between childhood maltreatment and obsessive-compulsive disorder comorbid with eating disorders: a cross-sectional study

BACKGROUND

Obsessive-compulsive disorder (OCD) and eating disorders (ED) share common features, including the presence of obsessions and compulsions, and they often co-occur. Additionally, there is a significant comorbidity between ED and childhood traumatic experiences (CTE), as well as between CTE and OCD. Various biological and environmental factors have been proposed to explain the connection between ED, OCD, and CTE. This study explores the link between CTE and the comorbidity of ED and OCD, with the hypothesis that specific types of CTE may increase the risk of developing OCD in individuals with ED.

METHODS

Participants (N = 562) were enrolled at an eating disorder unit in Montpellier, France, between March 2013 and January 2020. The Childhood Trauma Questionnaire (CTQ), Eating Disorder Examination Questionnaire (EDE-Q), and Mini International Neuropsychiatric Interview (MINI) were used to evaluate childhood maltreatment, assess clinical characteristics associated with ED, and categorize participants into two groups: patients with and without OCD.

RESULTS

Bivariate analysis revealed that patients with comorbid ED and OCD had higher EDE-Q scores (p < 0.001), more anxiety disorders (p < 0.001), depressive disorders (p = 0.02), post-traumatic stress disorder (PTSD) (p < 0.001), and a higher incidence of sexual abuse (p < 0.001) and physical neglect (p = 0.04) compared to those without OCD. Multivariate analysis showed that the association between CTE and OCD was influenced by the presence of an anxiety disorder (p = 0.01) and a higher EDE-Q total score (p = 0.03), with a significant association with a history of sexual abuse (p = 0.04).

CONCLUSIONS

This demonstrates that CTE increases the risk of comorbid OCD in ED patients, correlating with more clinically severe ED and a higher likelihood of anxiety disorders.

Therapeutic ketogenic diet as treatment for anorexia nervosa

Anorexia nervosa (AN) is a severe psychiatric disorder. However, we lack neurobiological models and interventions to explain and treat the core characteristics of food restriction, feeling fat, and body size overestimation. Research has made progress in understanding brain function involved in the pathophysiology of AN, but translating those results into biological therapies has been challenging. Studies have suggested that metabolic factors could contribute to developing and maintaining AN pathophysiology. Here, we describe a neurobiological model for why using a therapeutic ketogenic diet could address key alterations in brain function in AN and prevent the desire for weight loss and associated eating disorder-specific symptoms. This translational model is based on animal studies and human data and integrates behavioral traits, brain neural energy metabolism, and neurotransmitter function. Pilot data indicate that the intervention can dramatically reduce eating and body-related fears, although larger studies across illness stages still need to be conducted.

Genome-Wide Association Study of Obsessive-Compulsive Symptoms including 33,943 individuals from the general population

While 1-2% of individuals meet the criteria for a clinical diagnosis of obsessive-compulsive disorder (OCD), many more (~13-38%) experience subclinical obsessive-compulsive symptoms (OCS) during their life. To characterize the genetic underpinnings of OCS and its genetic relationship to OCD, we conducted the largest genome-wide association study (GWAS) meta-analysis of parent- or self-reported OCS to date (N = 33,943 with complete phenotypic and genome-wide data), combining the results from seven large-scale population-based cohorts from Sweden, the Netherlands, England, and Canada (including six twin cohorts and one cohort of unrelated individuals). We found no genome-wide significant associations at the single-nucleotide polymorphism (SNP) or gene-level, but a polygenic risk score (PRS) based on the OCD GWAS previously published by the Psychiatric Genetics Consortium (PGC-OCD) was significantly associated with OCS (Pfixed = 3.06 × 10-5). Also, one curated gene set (Mootha Gluconeogenesis) reached Bonferroni-corrected significance (Ngenes = 28, Beta = 0.79, SE = 0.16, Pbon = 0.008). Expression of genes in this set is high at sites of insulin mediated glucose disposal. Dysregulated insulin signaling in the etiology of OCS has been suggested by a previous study describing a genetic overlap of OCS with insulin signaling-related traits in children and adolescents. We report a SNP heritability of 4.1% (P = 0.0044) in the meta-analyzed GWAS, and heritability estimates based on the twin cohorts of 33-43%. Genetic correlation analysis showed that OCS were most strongly associated with OCD (rG = 0.72, p = 0.0007) among all tested psychiatric disorders (N = 11). Of all 97 tested phenotypes, 24 showed a significant genetic correlation with OCS, and 66 traits showed concordant directions of effect with OCS and OCD. OCS have a significant polygenic contribution and share genetic risk with diagnosed OCD, supporting the hypothesis that OCD represents the extreme end of widely distributed OCS in the population.

A transdiagnostic and translational framework for delineating the neuronal mechanisms of compulsive exercise in anorexia nervosa

OBJECTIVE

The development of novel treatments for anorexia nervosa (AN) requires a detailed understanding of the biological underpinnings of specific, commonly occurring symptoms, including compulsive exercise. There is considerable bio-behavioral overlap between AN and obsessive-compulsive disorder (OCD), therefore it is plausible that similar mechanisms underlie compulsive behavior in both populations. While the association between these conditions is widely acknowledged, defining the shared mechanisms for compulsive behavior in AN and OCD requires a novel approach.

METHODS

We present an argument that a better understanding of the neurobiological mechanisms that underpin compulsive exercise in AN can be achieved in two critical ways. First, by applying a framework of the neuronal control of OCD to exercise behavior in AN, and second, by taking better advantage of the activity-based anorexia (ABA) rodent model to directly test this framework in the context of feeding pathology.

RESULTS

A cross-disciplinary approach that spans preclinical, neuroimaging, and clinical research as well as compulsive neurocircuitry and behavior can advance our understanding of when, why, and how compulsive exercise develops in the context of AN and provide targets for novel treatment strategies.

DISCUSSION

In this article, we (i) link the expression of compulsive behavior in AN and OCD via a transition between goal-directed and habitual behavior, (ii) present disrupted cortico-striatal circuitry as a key substrate for the development of compulsive behavior in both conditions, and (iii) highlight the utility of the ABA rodent model to better understand the mechanisms of compulsive behavior relevant to AN.

PUBLIC SIGNIFICANCE

Individuals with AN who exercise compulsively are at risk of worse health outcomes and have poorer responses to standard treatments. However, when, why, and how compulsive exercise develops in AN remains inadequately understood. Identifying whether the neural circuitry underlying compulsive behavior in OCD also controls hyperactivity in the activity-based anorexia model will aid in the development of novel eating disorder treatment strategies for this high-risk population.

EEG Spatial-temporal Dynamics of Resting-state Activity in Young Women with Anorexia Nervosa: Preliminary Evidence

The aim of this study was to provide preliminary evidence on temporal dynamics of resting-state brain networks in youth with anorexia nervosa (AN) using electroencephalography (EEG). Resting-state EEG data were collected in 18 young women with AN and 18 healthy controls (HC). Between-group differences in brain networks were assessed using microstates analyses. Five microstates were identified across all subjects (A, B, C, D, E). Using a single set of maps representative of the whole dataset, group differences were identified for microstates A, C, and E. A common-for-all template revealed a relatively high degree of consistency in results for reduced time coverage of microstate C, but also an increased presence of microstate class E. AN and HC had different microstate transition probabilities, largely involving microstate A. Using LORETA, for microstate D, we found that those with AN had augmented activations in the left frontal inferior operculum, left insula, and bilateral paracentral lobule, compared with HC. For microstate E, AN had augmented activations in the para-hippocampal gyrus, caudate, pallidum, cerebellum, and cerebellar vermis. Our findings suggest altered microstates in young women with AN associated with integration of sensory and bodily signals, monitoring of internal/external mental states, and self-referential processes. Future research should examine how EEG-derived microstates could be applied to develop diagnostic and prognostic models of AN.

Taking better advantage of the activity-based anorexia model

The lack of specific treatments for anorexia nervosa (AN) is partly driven by an inadequate understanding of the neurobiological drivers of the condition. The activity-based anorexia (ABA) model recapitulates key characteristics of AN in rats and mice, and can be used to understand factors that predispose, maintain, and rescue anorectic behaviour. With the rapidly evolving suite of technologies to manipulate and record neural activity during the development of ABA, we are better placed than ever before to take advantage of this unique biobehavioural model in order to develop and refine novel treatments for AN. This will require a collective effort to bridge research disciplines in order to capitalise on knowledge gains from genetics, neurobiology, metabolism, and cognition.

The High Rates of Comorbidity among Neurodevelopmental Disorders: Reconsidering the Clinical Utility of Distinct Diagnostic Categories

The boundaries between neurodevelopmental disorders are often indistinct, even among specialists. But do these boundaries exist, or do experts struggle to distinguish and categorize symptoms in order to arrive at a dominant diagnosis while comorbidity continually leaves questions about where each disorder ends and begins? What should be reconsidered? The introduction of the term 'spectrum of neurodevelopmental disorders' could pave the way for a re-appraisal of the clinical continuum of neurodevelopmental disorders. This study aims to highlight the problems that emerge in the field of the differential diagnosis of neurodevelopmental disorders and propose a renegotiation of the distinctiveness criteria.

Task fMRI studies investigating inhibitory control in patients with obsessive-compulsive disorder and eating disorders: A comparative meta-analysis

BACKGROUND

Obsessive-compulsive disorder (OCD) and eating disorders (EDs) share similarities in terms of clinical characteristics and deficits in inhibitory control.

OBJECTIVE

To investigate whether inhibitory control could serve as a common behavioural phenotype between OCD and EDs and whether it might be underpinned by shared and/or distinct neural signatures.

METHOD

We performed a quantitative meta-analysis of brain function abnormalities during the inhibitory control task-based functional Magnetic Resonance Imaging (fMRI) scan across patients with OCD and EDs using seed-based d mapping (SDM).

RESULTS

The meta-analysis included sixteen OCD fMRI studies and ten EDs fMRI studies. And findings revealed that patients with OCD showed hypoactivation relative to healthy controls and patients with EDs in the anterior cingulate cortex, while compared to healthy controls and patients with OCD, patients with EDs showed hypoactivation in the right insula.

CONCLUSIONS

Patients with OCD and EDs are inclined to exhibit impaired inhibitory control, which may be attributed to different abnormal patterns of neural activation.

Genome-wide analysis of anorexia nervosa and major psychiatric disorders and related traits reveals genetic overlap and identifies novel risk loci for anorexia nervosa

Anorexia nervosa (AN) is a heritable eating disorder (50-60%) with an array of commonly comorbid psychiatric disorders and related traits. Although significant genetic correlations between AN and psychiatric disorders and related traits have been reported, their shared genetic architecture is largely understudied. We investigated the shared genetic architecture of AN and schizophrenia (SCZ), bipolar disorder (BIP), major depression (MD), mood instability (Mood), neuroticism (NEUR), and intelligence (INT). We applied the conditional false discovery rate (FDR) method to identify novel risk loci for AN, and conjunctional FDR to identify loci shared between AN and related phenotypes, to summarize statistics from relevant genome-wide association studies (GWAS). Individual GWAS samples varied from 72,517 to 420,879 participants. Using conditional FDR we identified 58 novel AN loci. Furthermore, we identified 38 unique loci shared between AN and major psychiatric disorders (SCZ, BIP, and MD) and 45 between AN and psychological traits (Mood, NEUR, and INT). In line with genetic correlations, the majority of shared loci showed concordant effect directions. Functional analyses revealed that the shared loci are involved in 65 unique pathways, several of which overlapped across analyses, including the "signal by MST1" pathway involved in Hippo signaling. In conclusion, we demonstrated genetic overlap between AN and major psychiatric disorders and related traits, and identified novel risk loci for AN by leveraging this overlap. Our results indicate that some shared characteristics between AN and related disorders and traits may have genetic underpinnings.

Predicting eating disorder and anxiety symptoms using disorder-specific and transdiagnostic polygenic scores for anorexia nervosa and obsessive-compulsive disorder

BACKGROUND

Clinical, epidemiological, and genetic findings support an overlap between eating disorders, obsessive-compulsive disorder (OCD), and anxiety symptoms. However, little research has examined the role of genetics in the expression of underlying phenotypes. We investigated whether the anorexia nervosa (AN), OCD, or AN/OCD transdiagnostic polygenic scores (PGS) predict eating disorder, OCD, and anxiety symptoms in a large developmental cohort in a sex-specific manner.

METHODS

Using summary statistics from Psychiatric Genomics Consortium AN and OCD genome-wide association studies, we conducted an AN/OCD transdiagnostic genome-wide association meta-analysis. We then calculated AN, OCD, and AN/OCD PGS in participants from the Avon Longitudinal Study of Parents and Children to predict eating disorder, OCD, and anxiety symptoms, stratified by sex (combined N = 3212-5369 per phenotype).

RESULTS

The PGS prediction of eating disorder, OCD, and anxiety phenotypes differed between sexes, although effect sizes were small. AN and AN/OCD PGS played a more prominent role in predicting eating disorder and anxiety risk than OCD PGS, especially in girls. AN/OCD PGS provided a small boost over AN PGS in the prediction of some anxiety symptoms. All three PGS predicted higher compulsive exercise across different developmental timepoints [β = 0.03 (s.e. = 0.01) for AN and AN/OCD PGS at age 14; β = 0.05 (s.e. = 0.02) for OCD PGS at age 16] in girls.

CONCLUSIONS

Compulsive exercise may have a transdiagnostic genetic etiology, and AN genetic risk may play a role in the presence of anxiety symptoms. Converging with prior twin literature, our results also suggest that some of the contribution of genetic risk may be sex-specific.

Obsessive-Compulsive Disorder and Metabolic Disorders: Overview and Future Perspective

Obsessive-compulsive disorder (OCD) has a bidirectional relationship with metabolic disorders. The purposes of this review are to decipher the links between OCD and metabolic disorders and to explore the etiological mechanism of OCD in metabolism, which may aid in early identification of and tailored interventions for OCD and metabolic disorders.

Childhood behavioral inhibition and overcontrol: Relationships with cognitive functioning, error monitoring, anxiety and obsessive-compulsive symptoms

Anxiety and obsessive-compulsive disorders are common childhood psychiatric disorders. Behavioral inhibition (BI) is a widely studied risk factor for anxiety. Less is known about overcontrol, a related behavioral phenotype characterized by concern for errors, perfectionism, and inflexibility and also associated with anxiety and obsessive-compulsive disorder. Both BI and overcontrol show associations with aberrant cognitive control and neural error responding (via the error-related negativity; ERN) yet it is unknown whether each imparts differential risk. Understanding whether overcontrol demonstrates independent associations from BI with cognitive functioning, neural error monitoring, and childhood anxiety and obsessive-compulsive presentations could aid in identifying a novel mechanistic treatment target. We assessed BI, overcontrol, cognitive functioning and psychopathology in a cross-sectional sample of 5-6 year old children (N = 126). Children completed an electroencephalogram (EEG) to assess the ERN. Overcontrol was associated with worse cognitive shifting, worse inhibitory control and higher anxiety and obsessive-compulsive symptoms, beyond BI. BI was associated with worse cognitive shifting, better inhibitory control and higher anxiety symptoms, beyond overcontrol. When assessed simultaneously, only overcontrol demonstrated a significant relationship with a blunted ERN. Moreover, overcontrol mediated (cross-sectionally) the well-established relationship between ERN and anxiety and obsessive-compulsive symptoms. BI and overcontrol impart differential risk for child cognitive functioning and anxiety while overcontrol demonstrates additional risk for aberrant neural error monitoring, anxiety and obsessive-compulsive presentations. Overcontrol may also be a mechanistic pathway between the ERN and transdiagnostic anxiety and obsessive-compulsive symptoms. Overcontrol may be a target warranted for early-childhood intervention in anxiety and OCD.

Genetic investigation of the contribution of body composition to anorexia nervosa in an electronic health record setting

Anorexia nervosa (AN) is a psychiatric disorder defined by anthropometric symptoms, such as low body weight, and cognitive-behavioral symptoms, such as restricted eating, fear of weight gain, and distorted body image. Recent studies have identified a genetic association between AN and metabolic/anthropometric factors, including body mass index (BMI). Although the reported associations may be under pleiotropic genetic influences, they may represent independent risk factors for AN. Here we examined the independent contributions of genetic predisposition to low body weight and polygenic risk (PRS) for AN in a clinical population (Vanderbilt University Medical Center biobank, BioVU). We fitted logistic and linear regression models in a retrospective case-control design (123 AN patients, 615 age-matched controls). We replicated the genetic correlations between PRS_BMI and AN (p = 1.12 × 10^-3, OR = 0.96), but this correlation disappeared when controlling for lowest BMI (p = 0.84, OR = 1.00). Additionally, we performed a phenome-wide association analysis of the PRS_AN and found that the associations with metabolic phenotypes were attenuated when controlling for PRS_BMI. These findings suggest that the genetic association between BMI and AN may be a consequence of the weight-related diagnostic criteria for AN and that genetically regulated anthropometric traits (like BMI) may be independent of AN psychopathology. If so, individuals with cognitive-behavioral symptomatology suggestive of AN, but with a higher PRS_BMI, may be under-diagnosed given current diagnostic criteria. Furthermore, PRS_BMI may serve as an independent risk factor for weight loss and weight gain during recovery.

Early intervention in obsessive-compulsive disorder: From theory to practice

Obsessive-compulsive disorder (OCD) is frequent and often disabling. Yet, correct diagnosis and appropriate treatment implementation are usually delayed, with undesirable consequences. In this paper we review the rationale for early intervention in OCD and provide recommendations for early intervention services. Two scenarios are discussed, i.e., subclinical (prodromal) obsessive-compulsive symptoms (OCS) and full-blown OCD. Although the typical patient with OCD reports a long history of subclinical OCS, longitudinal studies suggest most individuals with OCS in the community do not convert to full-blown OCD. Thus, research on "at risk" phenotypes for OCD and how they should incorporate different risk factors (e.g., polygenic risk scores) are badly needed. For this specific scenario, preventative treatments that are cheap, well tolerated and highly scalable (e.g., lifestyle interventions) are of major interest. On the other hand, increasing evidence suggests OCD to be a progressive disorder and the severity and duration of illness to be associated with both biological changes and increased clinical complexity, including greater number of physical and psychiatric comorbidities, increased family accommodation and worse treatment response. Therefore, prompt identification and early treatment implementation for full-blown OCD are also critical for ethical, clinical and therapeutic reasons. Based on the existing findings, we argue that, regardless of focusing on subclinical OCS or clinical OCD, early intervention services need to target a childhood age group. In addition to delivering well established treatments to people with full-blown OCD early on their illness, early intervention services also need to provide psychoeducation for patients, families and teachers.

The global assessment of OCD

Obsessive Compulsive Disorder (OCD) is a common mental disorder that often causes great sufferance, with substantial impairment in social functioning and quality of life and affects family and significant relationships. Notwithstanding its severity, OCD is often not adequately diagnosed, or it is diagnosed with delay, leading often to a long latency between onset of the OCD symptoms and the start of adequate treatments. Several factors contribute to the complexity of OCD's clinical picture: early age of onset, chronic course, heterogeneity of symptoms, high rate of comorbidity with other psychiatric disorders, slow or partial response to therapy. Therefore, it is of primary importance for clinicians involved in diagnosing OCD, to assess all aspects of the disorder. This narrative review focuses on the global assessment of OCD, highlighting crucial areas to explore, pointing out the clinical features which are relevant for the treatment of the disorder, and giving an overview of the psychometric tools that can be useful during the screening procedure.

Increased Habit Frequency in the Daily Lives of Patients with Acute Anorexia Nervosa

Strict eating routines and frequent rigid behavior patterns are commonly observed in patients with anorexia nervosa (AN). A recent theory proposes that while these behaviors may have been reinforced initially, they later become habitual. To date, however, research has been overly focused on eating-disorder (ED)-related habits. Over the course of seven days, we applied an ecological momentary assessment (EMA) to investigate the habit frequency and strength of ED-specific (food intake) and ED-unspecific (hygiene) habits in the daily lives of a sample of n = 57 AN and n = 57 healthy controls (HC). The results of the hierarchical models revealed that habits were significantly more likely in patients compared with HC for both categories, independently. Furthermore, a lower body mass index (BMI) was associated with increased habit frequency in AN. Our study strengthens the habit theory of AN by showing the relevance of habits beyond ED-specific behavioral domains. This also supports the development of innovative therapeutic interventions targeting habitual behavior in EDs.

Restlessness and an Increased Urge to Move (Drive for Activity) in Anorexia Nervosa May Strengthen Personal Motivation to Maintain Caloric Restriction and May Augment Body Awareness and Proprioception: A Lesson From Leptin Administration in Anorexia Nervosa

Anorexia nervosa (AN), a disorder of voluntary food restriction leading to severe weight loss in female adolescents, remains an enigma. In particular, the appropriation of the starved thin body into the self-concept in AN is a process insufficiently researched and still poorly understood. Healthy humans undergoing starvation experience a slowing of movements and avoid voluntary exercise. By contrast, AN tends to be not infrequently associated with voluntary, sometimes excessive and/or compulsive exercise. Such deliberate exercise, not reported in starvation, seems to be facilitated by an increased urge for movement and physical restlessness, particular to AN. The increased urge to move would reflect spontaneous daily activity, the energy expended for everything that is not sleeping, eating, or voluntary exercise. Our hypothesis is that the starvation-induced increased urge to move and restlessness may promote the development of AN. Reversal of the fasting state, by either high caloric food or by leptin administration, would be expected to reduce restlessness and the increased urge to move along with improvement in other symptoms in AN. This review explores the idea that such restless activation in AN, in itself and through accelerating body weight loss, might foster the integration of the starving body into the self-concept by (1) enhancing the person’s sense of self-control and sense of achievement and (2) through invigorating proprioception and through intensifying the perception of the changing body shape. (3) Tentative evidence from studies piloting leptin administration in chronic AN patients which support this hypothesis is reviewed. The findings show that short term administration of high doses of leptin indeed mitigated depressive feelings, inner tension, intrusive thoughts of food, and the increased urge to be physically active, easing the way to recovery, yet had little influence on the patients’ personal commitment to remain at a low weight. Full recovery then requires resolution of the individuals’ personal unresolved psychological conflicts through psychotherapy and frequently needs specialized treatment approaches to address psychiatric co-morbidities. AN might be conceptualized as a hereditary form of starvation resistance, facilitated by the effects of starvation on fitness allowing for an exceptionally intense personal commitment to perpetuate food restriction.

Changes in obsessive-compulsive symptoms during inpatient treatment of anorexia nervosa

BACKGROUND

Obsessive-compulsive disorder (OCD) is one of the most prevalent comorbidities in anorexia nervosa (AN). As AN is a severe, life-threatening condition, reducing obsessive-compulsive symptomatology is not the primary objective during treatment of AN and, thus, these symptoms may remain unchanged or may even increase in terms of a "symptom shift".

METHODS

In this retrospective analysis, we examined clinical records of 149 adolescents (n = 96, 64%) and adults (n = 53, 36%) with AN (6 males, 4%) who received inpatient treatment and completed the Obsessive-Compulsive Inventory-Revised at admission and discharge.

RESULTS

Obsessive-compulsive symptoms decreased from admission to discharge, irrespective of whether patients had comorbid OCD or not. Within-person decreases in obsessive-compulsive symptoms weakly correlated with increases in body weight.

CONCLUSIONS

These results indicate that obsessive-compulsive symptoms decrease during inpatient treatment of AN although they are not primarily targeted during treatment. Furthermore, these improvements seem to be associated with general improvements in AN symptomatology, suggesting the absence of a "symptom shift". Yet, effect sizes were small and obsessive-compulsive symptoms were still clinically elevated in patients with comorbid OCD at discharge, suggesting that these patients need OCD-specific, psychotherapeutic aftercare.

Psychiatric Comorbidity Among Eating Disorders and Obsessive-Compulsive Disorder and Underlying Shared Mechanisms and Features: An Updated Review

Eating disorders (EDs) are highly comorbid with obsessive-compulsive disorder (OCD), with comorbidity rates as high as 41%. In the current review, we summarize the literature regarding the prevalence of ED-OCD comorbidity. We also identify and review the literature assessing shared features (i.e., shared characteristics or symptoms) and mechanisms (i.e., variables that may explain ED or OCD symptoms) of EDs and OCD. Potential shared features of EDs and OCD include age of onset, course of illness, obsessions, compulsions and ritualistic behaviors, and thought action fusion. Shared mechanisms that may explain ED-OCD comorbidity include genetic and neurobiological mechanisms, anxiety and fear, repetitive negative thinking, perfectionism, intolerance of uncertainty, distress tolerance, and impulsivity. Based on these shared features and mechanisms, a theoretical conceptualization of ED and OCD comorbidity is developed, and outline considerations for assessment, differential diagnosis, treatment, and future research regarding ED-OCD comorbidity are described.

Efficacy and safety of antipsychotics and antidepressants in the treatment of anorexia nervosa: a systematic review

INTRODUCTION

The recommendations of the current guidelines are based on low quality evidence. Periodic updating is required, taking recent evidence into consideration.

OBJECTIVE

To synthesise the best available clinical evidence on the efficacy and safety of second-generation antidepressants and antipsychotics in patients with anorexia nervosa.

METHODS

Systematic review (CRD42020150577). We searched PubMed, SCOPUS, Ovid(Cochrane), EMBASE and LILACS for randomised clinical trials performed in patients with anorexia nervosa that evaluated the use of second-generation antipsychotics or oral antidepressants, at any dose and for any length of time, in outpatient and/or hospital treatment, taking weight (body mass index), psychopathological entities and safety as results.

RESULTS

Five studies were included, with four assessed as having a high risk of bias. The evidence indicates that patients receiving treatment with olanzapine or fluoxetine tend to stay in treatment programmes for longer. Olanzapine showed favourable results (one study) in terms of weight gain, but did not show the same results in psychopathology, where the evidence is contradictory.

CONCLUSIONS

In accordance with previous reviews, our work allows us to conclude that there is contradictory information on the efficacy of psychotropic drugs in the treatment of anorexia nervosa. Future work should focus on developing clinical trials of high methodological quality.

Neural Correlates of Executive Functioning in Anorexia Nervosa and Obsessive-Compulsive Disorder

Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) are commonly reported to co-occur and present with overlapping symptomatology. Executive functioning difficulties have been implicated in both mental health conditions. However, studies directly comparing these functions in AN and OCD are extremely limited. This review provides a synthesis of behavioral and neuroimaging research examining executive functioning in AN and OCD to bridge this gap in knowledge. We outline the similarities and differences in behavioral and neuroimaging findings between AN and OCD, focusing on set shifting, working memory, response inhibition, and response monitoring. This review aims to facilitate understanding of transdiagnostic correlates of executive functioning and highlights important considerations for future research. We also discuss the importance of examining both behavioral and neural markers when studying transdiagnostic correlates of executive functions.

Higher-Order Inputs Involved in Appetite Control

The understanding of the neural control of appetite sheds light on the pathogenesis of eating disorders such as anorexia nervosa and obesity. Both diseases are a result of maladaptive eating behaviors (overeating or undereating) and are associated with life-threatening health problems. The fine regulation of appetite involves genetic, physiological, and environmental factors, which are detected and integrated in the brain by specific neuronal populations. For centuries, the hypothalamus has been the center of attention in the scientific community as a key regulator of appetite. The hypothalamus receives and sends axonal projections to several other brain regions that are important for the integration of sensory and emotional information. These connections ensure that appropriate behavioral decisions are made depending on the individual's emotional state and environment. Thus, the mechanisms by which higher-order brain regions integrate exteroceptive information to coordinate feeding is of great importance. In this review, we will focus on the functional and anatomical projections connecting the hypothalamus to the limbic system and higher-order brain centers in the cortex. We will also address the mechanisms by which specific neuronal populations located in higher-order centers regulate appetite and how maladaptive eating behaviors might arise from altered connections among cortical and subcortical areas with the hypothalamus.

Genetics and neurobiology of eating disorders

Eating disorders (anorexia nervosa, bulimia nervosa and binge-eating disorder) are a heterogeneous class of complex illnesses marked by weight and appetite dysregulation coupled with distinctive behavioral and psychological features. Our understanding of their genetics and neurobiology is evolving thanks to global cooperation on genome-wide association studies, neuroimaging, and animal models. Until now, however, these approaches have advanced the field in parallel, with inadequate cross-talk. This review covers overlapping advances in these key domains and encourages greater integration of hypotheses and findings to create a more unified science of eating disorders. We highlight ongoing and future work designed to identify implicated biological pathways that will inform staging models based on biology as well as targeted prevention and tailored intervention, and will galvanize interest in the development of pharmacologic agents that target the core biology of the illnesses, for which we currently have few effective pharmacotherapeutics.

In pursuit of biomarkers for predicting susceptibility to activity-based anorexia in adolescent female rats

OBJECTIVE

Identifying risk factors that contribute to the development of anorexia nervosa (AN) is critical for the implementation of early intervention strategies. Anxiety, obsessive-compulsive behavior, and immune dysfunction may be involved in the development of AN; however, their direct influence on susceptibility to the condition remains unclear. Here, we used the activity-based anorexia (ABA) model to examine whether activity, anxiety-like behavior, compulsive behavior, and circulating immune markers predict the subsequent development of pathological weight loss.

METHOD

Female Sprague-Dawley rats (n = 44) underwent behavioral testing before exposure to ABA conditions after which they were separated into susceptible and resistant subpopulations. Blood was sampled before behavioral testing and after recovery from ABA to screen for proinflammatory cytokines.

RESULTS

Rats that were vulnerable to pathological weight loss differed significantly from resistant rats on all key ABA parameters. While the primary measures of anxiety-like or compulsive behavior were not shown to predict vulnerability to ABA, increased locomotion and anxiety-like behavior were both associated with the extent of weight loss in susceptible but not resistant animals. Moreover, the change in expression of proinflammatory markers IL-4 and IL-6 evoked by ABA was associated with discrete vulnerability factors. Intriguingly, behavior related to risk assessment was shown to predict vulnerability to ABA.

DISCUSSION

We did not find undisputable behavioral or immune predictors of susceptibility to pathological weight loss in the ABA rat model. Future research should examine the role of cognition in the development of ABA, dysfunction of which may represent an endophenotype linking anorectic, anxiety-like and compulsive behavior.

PUBLIC SIGNIFICANCE

Anorexia nervosa (AN) has among the highest mortality rates of all psychiatric disorders and treatment options remain limited in their efficacy. Understanding what types of risk factors contribute to the development of AN is essential for implementing early intervention strategies. This study describes how some of the most common psychological features of AN could be used to predict susceptibility to pathological weight loss in a well-established animal model.

The role of early-life family composition and parental socio-economic status as risk factors for obsessive-compulsive disorder in a Danish national cohort

Research on early-life family environment on obsessive-compulsive disorder (OCD) risk is limited, and sex differences have not been sufficiently studied. We investigated early-life family composition and parental socio-economic status (SES) as OCD risk factors while stratifying for sex in a sample of 1,154,067 individuals from the Danish population (7550 of whom had OCD). Data on early-life family composition (birth order, number of siblings, number of parents in household at proband age 6), parental SES at age 6 (parental income, occupation, and education level), history of parental psychiatric illness, and parental age at birth on OCD risk (i.e., an ICD-10 diagnosis of F42.x) were obtained from Danish population registers. Survival analyses using Cox regression were performed with age as the underlying time variable. Analyses were adjusted for calendar time, and differential effect by sex was tested for exposures. We found that birth order and advanced maternal age were risk factors for OCD in males, and being an only child was associated with increased OCD risk in both sexes. Early childhood SES variables including parental education, occupation, and income were associated with OCD risk, and these effects were more pronounced in females. Significant interaction effects for parental education/occupation and the presence of non-OCD psychiatric diagnoses in the proband also emerged. Our results suggest that early-life SES and family composition may be important risk factors for OCD, and heterogeneity in OCD cases in terms of psychiatric comorbidities, as well as sex differences should be carefully examined in relation to risk factors.

Obsessive-compulsive symptoms in young women affected with anorexia nervosa, and their relationship with personality, psychopathology, and attachment style

PURPOSE

Obsessive-compulsive symptoms (OC) are associated with greater morbidity and worse prognosis in anorexia nervosa (AN). We assessed the presence of non-eating OC in participants with AN and related them with their psychopathology, personality, and attachment style features.

METHODS

Young women with AN (N = 41, 30 restrictor and 11 binge-purging type) were assessed on the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). These participants with AN and 82 healthy controls (HC) completed the Temperament and Character Inventory (TCI), Eating Disorder Inventory-2 (EDI-2), Symptom Checklist-90 (SCL-90), Toronto Alexithymia Scale (TAS-20), and Attachment Style Questionnaire (ASQ). The association between Y-BOCS scores and indexes of psychopathology, personality, and attachment were examined.

RESULTS

AN had significantly higher scores than HC on the EDI-2, SCL-90, TAS-20, ASQ-Need for Approval, and TCI-Harm Avoidance and Self-directedness. The Y-BOCS scores were significantly correlated with ASQ-Need for Approval, TAS-20-Difficulty in Describing Feelings, SCL-90-Phobic Anxiety, and Anxiety, EDI-2-Drive to Thinness, and Asceticism. Need for Approval displayed the strongest correlation with OC symptoms. Difficulty in describing feelings displayed the strongest correlation with compulsive OC symptoms.

CONCLUSIONS

OC traits in AN were primarily associated with measures of insecure attachment rather than to their eating disorder or general psychopathology. Therapeutic approaches to correcting insecure attachment may be considered as a possible approach to treating AN patients with OC. The study supports a new psychopathological perspective for understanding the meaning of OC symptoms in AN.

LEVEL OF EVIDENCE

III: Evidence obtained from cohort or case-control analytic studies.

A scoping review and comparison of approaches for measuring genetic heterogeneity in psychiatric disorders

An improved understanding of genetic etiological heterogeneity in a psychiatric condition may help us (a) isolate a neurophysiological 'final common pathway' by identifying its upstream genetic origins and (b) facilitate characterization of the condition's phenotypic variation. This review aims to identify existing genetic heterogeneity measurements in the psychiatric literature and provides a conceptual review of their mechanisms, limitations, and assumptions. The Scopus database was searched for studies that quantified genetic heterogeneity or correlation of psychiatric phenotypes with human genetic data. Ninety studies were included. Eighty-seven reports quantified genetic correlation, five applied genomic structural equation modelling, three evaluated departure from the Hardy-Weinberg equilibrium at one or more loci, and two applied a novel approach known as MiXeR. We found no study that rigorously measured genetic etiological heterogeneity across a large number of markers. Developing such approaches may help better characterize the biological diversity of psychopathology.

The Rise and Fall of Dopamine: A Two-Stage Model of the Development and Entrenchment of Anorexia Nervosa

Dopamine has long been implicated as a critical neural substrate mediating anorexia nervosa (AN). Despite nearly 50 years of research, the putative direction of change in dopamine function remains unclear and no consensus on the mechanistic role of dopamine in AN has been achieved. We hypothesize two stages in AN- corresponding to initial development and entrenchment- characterized by opposite changes in dopamine. First, caloric restriction, particularly when combined with exercise, triggers an escalating spiral of increasing dopamine that facilitates the behavioral plasticity necessary to establish and reinforce weight-loss behaviors. Second, chronic self-starvation reverses this escalation to reduce or impair dopamine which, in turn, confers behavioral inflexibility and entrenchment of now established AN behaviors. This pattern of enhanced, followed by impaired dopamine might be a common path to many behavioral disorders characterized by reinforcement learning and subsequent behavioral inflexibility. If correct, our hypothesis has significant clinical and research implications for AN and other disorders, such as addiction and obesity.

Cognitive and Experienced Flexibility in Patients With Anorexia Nervosa and Obsessive Compulsive Disorder

OBJECTIVE

Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) share a neuropsychological profile characterized by cognitive inflexibility as evident in set-shifting problems, and by strong detail focus. Clinically, both patient groups display a strong rigidity which may be explained by these neurocognitive difficulties. Cognitive inflexibility may hinder treatment uptake and help explain suboptimal treatment outcomes in both AN and OCD. This is the first study to compare clinical AN and OCD groups andto examine similarities and differences in cognitive flexibility. Specifically, this study aims to investigate neuropsychological outcomes and self-reported difficulties in both clinical groups and a control group, and explore associations between the different flexibility outcomes and illness.

METHOD

Two hundred participants (61 AN, 72 OCD and 67 HC) performed neuropsychological tasks on set-shifting abilities (Trail Making Task, Stroop color-word interference, Intradimensional-Extradimensional shift task), detail focus (Group Embedded Figures Test) and self-reported set-shifting abilities and attention to detail (DFlex).

RESULTS

Similarities between patient groups were found in terms of reduced set-shifting ability on the Trail Making Task and detail focus. Moreover, both patient groups self-reported more set-shifting problems but a less strong detail focus than HC, which in turn were not related to neuropsychological task outcomes in either of the groups. In both patient groups longer illness duration was associated to longer reaction times in the switching tasks and for both groups symptom severity was associated to higher experienced inflexibility and attention to detail.

CONCLUSION

Cognitive inflexibility processes are largely similar in patients with AN and OCD. Both patient groups report inflexibility, yet this is unrelated to neuropsychological outcomes. Illness duration seems to contribute to poorer set-shifting and higher illness severity is linked to more experienced inflexibility. Findings highlight the need for entangling different domains of cognitive flexibility and detail focus and examining self-report measures for a cohesive understanding of clinically relevant flexibility weaknesses in AN and OCD.

Suppression of Corticostriatal Circuit Activity Improves Cognitive Flexibility and Prevents Body Weight Loss in Activity-Based Anorexia in Rats

BACKGROUND

The ability to adapt behavior to changing environmental circumstances, or cognitive flexibility, is impaired in multiple psychiatric conditions, including anorexia nervosa (AN). Exaggerated prefrontal cortical activity likely underpins the inflexible thinking and rigid behaviors exhibited by patients with AN. A better understanding of the neural basis of cognitive flexibility is necessary to enable treatment approaches that may target impaired executive control.

METHODS

Utilizing the activity-based anorexia (ABA) model and touchscreen operant learning paradigms, we investigated the neurobiological link between pathological weight loss and cognitive flexibility. We used pathway-specific chemogenetics to selectively modulate activity in neurons of the medial prefrontal cortex (mPFC) projecting to the nucleus accumbens shell (AcbSh) in female Sprague Dawley rats.

RESULTS

DREADD (designer receptor exclusively activated by designer drugs)-based inhibition of the mPFC-AcbSh pathway prevented weight loss in ABA and improved flexibility during early reversal learning by reducing perseverative responding. Modulation of activity within the mPFC-AcbSh pathway had no effect on running, locomotor activity, or feeding under ad libitum conditions, indicating the specific involvement of this circuit in conditions of dysregulated reward.

CONCLUSIONS

Parallel attenuation of weight loss in ABA and improvement of cognitive flexibility following suppression of mPFC-AcbSh activity align with the relationship between disrupted prefrontal function and cognitive rigidity in AN patients. The identification of a neurobiological correlate between cognitive flexibility and pathological weight loss provides a unique insight into the executive control of feeding behavior. It also highlights the utility of the ABA model for understanding the biological bases of cognitive deficits in AN and provides context for new treatment strategies.

A comprehensive gene-centric pleiotropic association analysis for 14 psychiatric disorders with GWAS summary statistics

BACKGROUND

Recent genome-wide association studies (GWASs) have revealed the polygenic nature of psychiatric disorders and discovered a few of single-nucleotide polymorphisms (SNPs) associated with multiple psychiatric disorders. However, the extent and pattern of pleiotropy among distinct psychiatric disorders remain not completely clear.

METHODS

We analyzed 14 psychiatric disorders using summary statistics available from the largest GWASs by far. We first applied the cross-trait linkage disequilibrium score regression (LDSC) to estimate genetic correlation between disorders. Then, we performed a gene-based pleiotropy analysis by first aggregating a set of SNP-level associations into a single gene-level association signal using MAGMA. From a methodological perspective, we viewed the identification of pleiotropic associations across the entire genome as a high-dimensional problem of composite null hypothesis testing and utilized a novel method called PLACO for pleiotropy mapping. We ultimately implemented functional analysis for identified pleiotropic genes and used Mendelian randomization for detecting causal association between these disorders.

RESULTS

We confirmed extensive genetic correlation among psychiatric disorders, based on which these disorders can be grouped into three diverse categories. We detected a large number of pleiotropic genes including 5884 associations and 2424 unique genes and found that differentially expressed pleiotropic genes were significantly enriched in pancreas, liver, heart, and brain, and that the biological process of these genes was remarkably enriched in regulating neurodevelopment, neurogenesis, and neuron differentiation, offering substantial evidence supporting the validity of identified pleiotropic loci. We further demonstrated that among all the identified pleiotropic genes there were 342 unique ones linked with 6353 drugs with drug-gene interaction which can be classified into distinct types including inhibitor, agonist, blocker, antagonist, and modulator. We also revealed causal associations among psychiatric disorders, indicating that genetic overlap and causality commonly drove the observed co-existence of these disorders.

CONCLUSIONS

Our study is among the first large-scale effort to characterize gene-level pleiotropy among a greatly expanded set of psychiatric disorders and provides important insight into shared genetic etiology underlying these disorders. The findings would inform psychiatric nosology, identify potential neurobiological mechanisms predisposing to specific clinical presentations, and pave the way to effective drug targets for clinical treatment.

Cultural shifts in the symptoms of Anorexia Nervosa: The case of Orthorexia Nervosa

Orthorexia Nervosa (ON) is a term describing a fixation on food purity, involving ritualized eating patterns and a rigid avoidance of "unhealthy foods." Those self-identified as having ON tend to focus on food composition and feel immense guilt after eating food deemed "unhealthy." Although not formally recognized as a psychiatric disorder by the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), ON has received increasing attention since its identification in 1997. There is ongoing work to establish diagnostic and empirical tools for measuring ON; embedded in this is the question as to whether or not ON is a new eating disorder. In this paper, we argue ON is not a new psychiatric disorder but rather a new cultural manifestation of anorexia nervosa (AN). We begin by providing an overview of historical representations and classification of eating disorders, with a specific focus on AN. This is followed by discussion of the rise in diet culture and healthism since the 19th century. We conclude by examining the diagnostic validity and utility of ON through a discussion of empirical evidence. Classifying ON under the diagnostic umbrella of AN may improve our understanding of factors underlying restrictive eating behaviors.

Variability in the antioxidant MSRA gene affects the psychopathology of patients with anorexia nervosa

The objective is to determine whether variability in the MSRA gene, related to obesity and several psychiatric conditions, may be relevant for psychopathological symptoms common in Anorexia Nervosa (AN) and/or for the susceptibility to the disorder. A total of 629 women (233 AN patients and 396 controls) were genotyped for 14 tag-SNPs. Psychometric evaluation was performed with the EDI-2 and SCL-90R questionnaires. Genetic associations were carried out by logistic regression controlling for age and adjusting for multiple comparisons (FDR method). Two tag-SNPs, rs11249969 and rs81442 (with a pairwise r2 value of 0.41), were associated with the global EDI-2 score, which measures EDI-related psychopathology (adjusted FDR-q = 0.02 and 0.04, respectively). Moreover, rs81442 significantly modulated all the scales of the SCL-90R test that evaluates general psychopathology (FDR-q values ranged from 4.1E-04 to 0.011). A sliding-window analysis using adjacent 3-SNP haplotypes revealed a proximal region of the MSRA gene spanning 187.8 Kbp whose variability deeply affected psychopathological symptoms of the AN patients. Depression was the symptom that showed the strongest association with any of the constructed haplotypes (FDR-q = 3.60E-06). No variants were found to be linked to AN risk or anthropometric parameters in patients or controls. Variability in the MSRA gene locus modulates psychopathology often presented by AN patients.

Genomics of Obsessive-Compulsive Disorder-Toward Personalized Medicine in the Era of Big Data

Pathogenesis of obsessive-compulsive disorder (OCD) mainly involves dysregulation of serotonergic neurotransmission, but a number of other factors are involved. Genetic underprints of OCD fall under the category of "common disease common variant hypothesis," that suggests that if a disease that is heritable is common in the population (a prevalence >1-5%), then the genetic contributors-specific variations in the genetic code-will also be common in the population. Therefore, the genetic contribution in OCD is believed to come from multiple genes simultaneously and it is considered a polygenic disorder. Genomics offers a number of advanced tools to determine causal relationship between the exposure and the outcome of interest. Particularly, methods such as polygenic risk score (PRS) or Mendelian Randomization (MR) enable investigation of new pathways involved in OCD pathogenesis. This premise is also facilitated by the existence of publicly available databases that include vast study samples. Examples include population-based studies such as UK Biobank, China Kadoorie Biobank, Qatar Biobank, All of US Program sponsored by National Institute of Health or Generations launched by Yale University, as well as disease-specific databases, that include patients with OCD and co-existing pathologies, with the following examples: Psychiatric Genomics Consortium (PGC), ENIGMA OCD, The International OCD Foundation Genetics Collaborative (IOCDF-GC) or OCD Collaborative Genetic Association Study. The aim of this review is to present a comprehensive overview of the available Big Data resources for the study of OCD pathogenesis in the context of genomics and demonstrate that OCD should be considered a disorder which requires the approaches offered by personalized medicine.

Genetics of anorexia nervosa: an overview of genome-wide association studies and emerging biological links

Anorexia nervosa (AN) is a complex disorder with a strong genetic component. Comorbidities are frequent and there is substantial overlap with other disorders. The lack of understanding of the molecular and neuroanatomical causes has made it difficult to develop effective treatments and it is often difficult to treat in clinical practice. Recent advances in genetics have changed our understanding of polygenic diseases, increasing the possibility of understanding better how molecular pathways are intertwined. This review synthetizes the current state of genetic research providing an overview of genome-wide association studies (GWAS) findings in AN as well as overlap with other disorders, traits, pathways, and imaging results. This paper also discusses the different putative global pathways that are contributing to the disease including the evidence for metabolic and psychiatric origin of the disease.

Genetics of obsessive-compulsive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is a psychiatric disorder with multiple symptom dimensions (e.g. contamination, symmetry). OCD clusters in families and decades of twin studies clearly demonstrate an important role for genetics in the etiology of the disorder.

METHODS

In this review, we summarize the genetic epidemiology and molecular genetic studies of OCD and obsessive-compulsive symptoms.

RESULTS

OCD is a heritable, polygenic disorder with contributions from both common and rare variants, including de novo deleterious variations. Multiple studies have provided reliable support for a large additive genetic contribution to liability to OCD, with discrete OCD symptom dimensions having both shared and unique genetic risks. Genome-wide association studies have not produced significant results yet, likely because of small sample sizes, but larger meta-analyses are forthcoming. Both twin and genome-wide studies show that OCD shares genetic risk with its comorbid conditions (e.g. Tourette syndrome and anorexia nervosa).

CONCLUSIONS

Despite significant efforts to uncover the genetic basis of OCD, the mechanistic understanding of how genetic and environmental risk factors interact and converge at the molecular level to result in OCD's heterogeneous phenotype is still mostly unknown. Future investigations should increase ancestral genetic diversity, explore age and/or sex differences in genetic risk for OCD and expand the study of pharmacogenetics, gene expression, gene × environment interactions and epigenetic mechanisms for OCD.

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.

Comorbid obsessive-compulsive disorder in individuals with eating disorders: An epidemiological meta-analysis

The present study aimed to provide a precise, meta-analytic estimate of the prevalence of obsessive-compulsive disorder (OCD) amongst those with a current primary eating disorder (ED) diagnosis, and to isolate its predictors. An online search of PubMed and PsycINFO was conducted with a Boolean search phrase incorporating keywords related to OCD, EDs, comorbidity, prevalence, and epidemiology, complemented by references coded from related review articles and contact with experts in the field. Articles were included if they (a) reported an observational study examining current ED diagnoses, (b) used a semi-structured or structured diagnostic interview for OCD and ED diagnosis, (c) applied DSM or ICD criteria, (d) included adolescent or adult samples (age > 12), (e) included patient or community samples, and (f) reported lifetime or current OCD comorbidity. From the 846 articles identified, 35 lifetime and 42 current estimates were calculated. OCD prevalence was extracted from each study for each ED diagnostic category, along with eleven additional potential moderators. Analyses revealed an aggregate lifetime OCD prevalence of 13.9% CI_95% [10.4 to 18.1] and current OCD prevalence of 8.7% CI_95% [5.8 to 11.8] across EDs. Moderator analyses revealed the prevalence of and risk for OCD in EDs to be greatest in anorexia nervosa binge-eating purging type (ANBP). Further, OCD is most prevalent amongst patient samples than samples recruited from the community.

Deep brain stimulation for psychiatric disorders: role of imaging in identifying/confirming DBS targets, predicting, and optimizing outcome and unravelling mechanisms of action

Following the established application of deep brain stimulation (DBS) in the treatment of movement disorders, new non-neurological indications have emerged, such as for obsessive-compulsive disorders, major depressive disorder, dementia, Gilles de la Tourette Syndrome, anorexia nervosa, and addictions. As DBS is a network modulation surgical treatment, the development of DBS for both neurological and psychiatric disorders has been partly driven by advances in neuroimaging, which has helped explain the brain networks implicated. Advances in magnetic resonance imaging connectivity and electrophysiology have led to the development of the concept of modulating widely distributed, complex brain networks. Moreover, the increasing number of targets for treating psychiatric disorders have indicated that there may be a convergence of the effect of stimulating different targets for the same disorder, and the effect of stimulating the same target for different disorders. The aim of this paper is to review the imaging studies of DBS for psychiatric disorders. Imaging, and particularly connectivity analysis, offers exceptional opportunities to better understand and even predict the clinical outcomes of DBS, especially where there is a lack of objective biomarkers that are essential to properly guide DBS pre- and post-operatively. In future, imaging might also prove useful to individualize DBS treatment. Finally, one of the most important aspects of imaging in DBS is that it allows us to better understand the brain through observing the changes of the functional connectome under neuromodulation, which may in turn help explain the mechanisms of action of DBS that remain elusive.

Associations of observed preschool performance monitoring with brain functional connectivity in adolescence

Monitoring one's performance helps detect errors and adapt to prevent future mistakes. However, elevated performance monitoring is associated with increased checking behaviors and perfectionism and is characteristic of multiple psychiatric disorders. Understanding how heightened performance monitoring in early childhood relates to subsequent brain connectivity may elucidate mechanistic risk factors that influence brain and psychiatric outcomes. The aim of this study was to examine the association between performance monitoring in preschool-aged children and functional connectivity during adolescence. In the current prospective longitudinal study, we performed seed-based functional connectivity analysis using a dorsal anterior cingulate cortex (dACC) seed to assess brain-behavior relationships between observationally coded performance monitoring in preschool-aged children and adolescent functional connectivity (n = 79). We also utilized enrichment analysis to investigate network-level connectome-wide associations. Seed-based analysis revealed negative correlations between preschool performance monitoring and adolescent fc between dACC and orbitofrontal and dorsolateral prefrontal cortex while a positive correlation was observed between dACC-occipital cortex connectivity. Enrichment analysis revealed a negative correlation between preschool performance monitoring and connectivity between motor (MOT) - cingulo-opercular (CO) and salience (SN) - Reward (REW) and a positive correlation with MOT-DMN, and cerebellum (CB) - motor connectivity. Elevated performance monitoring in early childhood is associated with functional connectivity during adolescence in regions and networks associated with cognitive control, sensorimotor processing and cortico-striatal-thalamic-cortico (CTSC) aberrations. These regions and networks are implicated in psychiatric disorders characterized by elevated performance monitoring. Findings shed light on a mechanistic risk factor in early childhood with long-term associations with neural functioning.

Comorbid mental disorders during long-term course in a nationwide cohort of patients with anorexia nervosa

OBJECTIVE

Comorbid mental disorders in anorexia nervosa during long-term course require detailed studies.

METHOD

This matched cohort study was based on nationwide Danish register data of all patients born 1961-2008 with a first-time ICD-10 diagnosis of anorexia nervosa (AN) between 1994 and 2018 at age 8-32 and matched controls taken from all individuals without an eating disorder (ED). For nine categories of non-eating mental disorders, time from date of first AN-diagnosis (inclusion date) to time of first diagnosis, accounting for censoring, was studied by use of time-stratified Cox models.

RESULTS

A total of 9,985 patients with AN (93.5% females) and 49,351 matched controls were followed for a median (IQR) of 9.0 (4.4-15.7) years. For patients, there was about 25% and 55% risk of receiving any non-ED disorder during the first 2 years and two decades after inclusion, respectively. A hazard ratio (HR) of seven for any non-ED was found for the first 12 months after inclusion, a ratio that reduced to two at five or more years after inclusion. During the first years, large HRs ranging in 6-9 were found for affective, autism spectrum, personality, and obsessive-compulsive disorders with the latter displaying the highest continuous increased risk. The HR at 12 months after inclusion was highest for any non-ED disorder and affective disorders in patients aged 8-13 at diagnosis.

DISCUSSION

Comorbid mental disorders in AN are most frequently diagnosed in the first years after diagnosis of AN and on longer terms imply a double immediate risk.

Polygenic Heterogeneity Across Obsessive-Compulsive Disorder Subgroups Defined by a Comorbid Diagnosis

Among patients with obsessive-compulsive disorder (OCD), 65-85% manifest another psychiatric disorder concomitantly or at some other time point during their life. OCD is highly heritable, as are many of its comorbidities. A possible genetic heterogeneity of OCD in relation to its comorbid conditions, however, has not yet been exhaustively explored. We used a framework of different approaches to study the genetic relationship of OCD with three commonly observed comorbidities, namely major depressive disorder (MDD), attention-deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD). First, using publicly available summary statistics from large-scale genome-wide association studies, we compared genetic correlation patterns for OCD, MDD, ADHD, and ASD with 861 somatic and mental health phenotypes. Secondly, we examined how polygenic risk scores (PRS) of eight traits that showed heterogeneous correlation patterns with OCD, MDD, ADHD, and ASD partitioned across comorbid subgroups in OCD using independent unpublished data from the Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSYCH). The comorbid subgroups comprised of patients with only OCD (N = 366), OCD and MDD (N = 1,052), OCD and ADHD (N = 443), OCD and ASD (N = 388), and OCD with more than 1 comorbidity (N = 429). We found that PRS of all traits but BMI were significantly associated with OCD across all subgroups (neuroticism: p = 1.19 × 10-32, bipolar disorder: p = 7.51 × 10-8, anorexia nervosa: p = 3.52 × 10-20, age at first birth: p = 9.38 × 10-5, educational attainment: p = 1.56 × 10-4, OCD: p = 1.87 × 10-6, insomnia: p = 2.61 × 10-5, BMI: p = 0.15). For age at first birth, educational attainment, and insomnia PRS estimates significantly differed across comorbid subgroups (p = 2.29 × 10-4, p = 1.63 × 10-4, and p = 0.045, respectively). Especially for anorexia nervosa, age at first birth, educational attainment, insomnia, and neuroticism the correlation patterns that emerged from genetic correlation analysis of OCD, MDD, ADHD, and ASD were mirrored in the PRS associations with the respective comorbid OCD groups. Dissecting the polygenic architecture, we found both quantitative and qualitative polygenic heterogeneity across OCD comorbid subgroups.

A dimensional perspective on the genetics of obsessive-compulsive disorder

This review covers recent findings in the genomics of obsessive-compulsive disorder (OCD), obsessive-compulsive symptoms, and related traits from a dimensional perspective. We focus on discoveries stemming from technical and methodological advances of the past five years and present a synthesis of human genomics research on OCD. On balance, reviewed studies demonstrate that OCD is a dimensional trait with a highly polygenic architecture and genetic correlations to multiple, often comorbid psychiatric phenotypes. We discuss the phenotypic and genetic findings of these studies in the context of the dimensional framework, relying on a continuous phenotype definition, and contrast these observations with discoveries based on a categorical diagnostic framework, relying on a dichotomous case/control definition. Finally, we highlight gaps in knowledge and new directions for OCD genetics research.

Disrupted pathways from frontal-parietal cortex to basal ganglia and cerebellum in patients with unmedicated obsessive compulsive disorder as observed by whole-brain resting-state effective connectivity analysis - a small sample pilot study

OBJECTIVE

To date, a systematic characterization of abnormalities in resting-state effective connectivity (rsEC) in obsessive-compulsive disorder (OCD) is lacking. The present study aimed to systematically characterize whole-brain rsEC in OCD patients as compared to healthy controls.

METHODS

Using resting-state fMRI data of 50 unmedicated patients with OCD and 50 healthy participants, we constructed whole-brain rsEC networks using Granger causality analysis followed by univariate and multivariate comparisons between patients and controls. Similar analyses were performed for resting-state functional connectivity (rsFC) networks to examine how rsFC and rsEC differentially capture abnormal brain connectivity in OCD.

RESULTS

Univariate comparisons identified 10 rsEC networks that were significantly disrupted in patients, and which were mainly associated with frontal-parietal cortex, basal ganglia, and cerebellum. Conversely, abnormal rsFC networks were widely distributed throughout the whole brain. Multivariate pattern analysis revealed a classification accuracy as high as 80.5% for distinguishing patients from controls using combined whole-brain rsEC and rsFC.

CONCLUSIONS

The results of the present study suggest disrupted communication of information from frontal-parietal cortex to basal ganglia and cerebellum in OCD patients. Using combined whole-brain rsEC and rsFC, multivariate pattern analysis revealed a classification accuracy as high as 80.5% for distinguishing patients from controls. The alterations observed in OCD patients could aid in identifying treatment mechanisms for OCD.

The Polygenic Nature and Complex Genetic Architecture of Specific Learning Disorder

Specific Learning Disorder (SLD) is a multifactorial, neurodevelopmental disorder which may involve persistent difficulties in reading (dyslexia), written expression and/or mathematics. Dyslexia is characterized by difficulties with speed and accuracy of word reading, deficient decoding abilities, and poor spelling. Several studies from different, but complementary, scientific disciplines have investigated possible causal/risk factors for SLD. Biological, neurological, hereditary, cognitive, linguistic-phonological, developmental and environmental factors have been incriminated. Despite worldwide agreement that SLD is highly heritable, its exact biological basis remains elusive. We herein present: (a) an update of studies that have shaped our current knowledge on the disorder’s genetic architecture; (b) a discussion on whether this genetic architecture is ‘unique’ to SLD or, alternatively, whether there is an underlying common genetic background with other neurodevelopmental disorders; and, (c) a brief discussion on whether we are at a position of generating meaningful correlations between genetic findings and anatomical data from neuroimaging studies or specific molecular/cellular pathways. We conclude with open research questions that could drive future research directions.

Genetic and epigenetic architecture of Obsessive-Compulsive Disorder: In search of possible diagnostic and prognostic biomarkers

Obsessive-Compulsive Disorder (OCD) is a prevalent and severe clinical condition whose hallmarks are excessive, unwanted thoughts (obsessions) and repetitive behaviors (compulsions). The onset of symptoms generally occurs during pre-adult life and typically affects subjects in different aspects of their life's, compromising social and professional relationships. Although robust evidence suggests a genetic component in the etiopathogenesis of OCD, the causes of the disorder are still not completely understood. It is thus of relevance to take into account how genes interact with environmental risk factors, thought to be mediated by epigenetic mechanisms. We here provide an overview of genetic and epigenetic mechanisms of OCD, focusing on the modulation of key central nervous system genes, in the attempt to suggest possible disease biomarkers.

Dissection of the Genetic Association between Anorexia Nervosa and Obsessive-Compulsive Disorder at the Network and Cellular Levels

Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) exhibit a high co-morbidity rate, similar symptoms, and a shared genetic basis. However, an understanding of the specific underlying mechanisms of these commonalities is currently limited. Here, we collected Genome-Wide Association Analysis results for AN and OCD, and obtained genes hit by the top SNPs as the risk genes. We then carried out an integrative coexpression network analysis to explore the convergence and divergence of AN and OCD risk genes. At first, we observed that the AN risk genes were enriched in coexpression modules that involved extracellular matrix functions and highly are expressed in the postnatal brain, limbic system, and non-neuronal cell types, while the OCD risk genes were enriched in modules of synapse function, the prenatal brain, cortex layers, and neurons. Next, by comparing the expressions from the eating disorder and OCD postmortem patient brain tissues, we observed both disorders have similar prefrontal cortex expression alterations influencing the synapse transmission, suggesting that the two diseases could have similar functional pathways. We found that the AN and OCD risk genes had distinct functional and spatiotemporal enrichment patterns but carried similar expression alterations as a disease mechanism, which may be one of the key reasons they had similar but not identical clinical phenotypes.

Genomic relationships across psychiatric disorders including substance use disorders

BACKGROUND

A recent study investigated the genetic associations and latent genetic structure among eight psychiatric disorders using findings from genome-wide association studies (GWASs). No data from substance use disorders were included, while these represent an important category of mental disorders and could influence the latent genetic structure. We extended the original paper by recreating the genetic relationship matrix, graph, and latent genetic factor structure, including additional data from substance use disorders.

METHODS

We used GWAS summary statistics of 11 psychiatric disorders, including alcohol dependence, nicotine dependence, and cannabis use disorder. We estimated genetic correlations between all traits in Linkage Disequilibrium-Score Regression. A graph was created to illustrate the network of genetic correlations. We then used the genetic relationships to model a latent genetic factor structure.

RESULTS

Alcohol and nicotine dependence showed significant genetic correlations with several other psychiatric disorders, including ADHD, schizophrenia, and major depression. Cannabis use disorder was only significantly associated with ADHD. The addition of substance use disorders resulted in some changes in the latent structure of the factor model when compared to the original model including eight disorders. All substance use disorders contributed mostly to Factor 3, a heterogeneous factor with also loadings from ADHD, major depression, Autism Spectrum Disorders, and Tourette Syndrome.

CONCLUSIONS

Alcohol and nicotine dependence show widespread genetic correlations with other psychiatric disorders. Including substance use disorders in the factor analysis results in some changes in the underlying genetic factor structure. Given the instability of such models, identified structures should be interpreted with caution.