Endophenotypes: A conceptual link between anorexia nervosa and autism spectrum disorder

Disease-specific prioritization of non-coding GWAS variants based on chromatin accessibility

Non-protein-coding genetic variants are a major driver of the genetic risk for human disease; however, identifying which non-coding variants contribute to diseases and their mechanisms remains challenging. In silico variant prioritization methods quantify a variant's severity, but for most methods, the specific phenotype and disease context of the prediction remain poorly defined. For example, many commonly used methods provide a single, organism-wide score for each variant, while other methods summarize a variant's impact in certain tissues and/or cell types. Here, we propose a complementary disease-specific variant prioritization scheme, which is motivated by the observation that variants contributing to disease often operate through specific biological mechanisms. We combine tissue/cell-type-specific variant scores (e.g., GenoSkyline, FitCons2, DNA accessibility) into disease-specific scores with a logistic regression approach and apply it to ∼25,000 non-coding variants spanning 111 diseases. We show that this disease-specific aggregation significantly improves the association of common non-coding genetic variants with disease (average precision: 0.151, baseline = 0.09), compared with organism-wide scores (GenoCanyon, LINSIGHT, GWAVA, Eigen, CADD; average precision: 0.129, baseline = 0.09). Further on, disease similarities based on data-driven aggregation weights highlight meaningful disease groups, and it provides information about tissues and cell types that drive these similarities. We also show that so-learned similarities are complementary to genetic similarities as quantified by genetic correlation. Overall, our approach demonstrates the strengths of disease-specific variant prioritization, leads to improvement in non-coding variant prioritization, and enables interpretable models that link variants to disease via specific tissues and/or cell types.

Social attention in anorexia nervosa and autism spectrum disorder: Role of social motivation

LAY ABSTRACT

Research suggests a relationship between autism and anorexia nervosa. For example, rigid and inflexible behaviour, a preference for routine and social difficulties are seen in both conditions. In this study, we examined whether people with anorexia and people with autism show similarities in social attention (where they look while engaging in social interactions or watching a scene with people interacting). This could help us understand why people with anorexia and autism experience difficulties in social situations. Participants with either anorexia or autism, as well as participants with no mental health problems watched a video of a social scene while we recorded which parts of the scene they looked at with an eye-tracker. Participants also completed questionnaires to assess characteristics of autism. We found that autistic participants looked at faces less than typically developing participants. However, participants with anorexia did not show a similar reduction in attention to faces, contrary to our predictions. Autistic features were not related to attention in either group. The results suggest that autistic people may miss important social cues (like facial expressions), potentially contributing to social difficulties. However, this mechanism does not appear explain social difficulties in people with anorexia.

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.

Cognitive flexibility and attention to detail in adolescents and adults with severe forms of anorexia nervosa

OBJECTIVE

To determine if adolescents and adults diagnosed with anorexia nervosa differ in their levels of cognitive flexibility and attention to detail independently of potential confounds.

METHOD

Sixty-two adolescents and 54 adults were assessed while receiving inpatient treatment and completed the following self-reports: Eating Disorders Examination Questionnaire, Maudsley Obsessive Compulsive Inventory and Hospital Anxiety and Depression scale. Performance-based evaluations included the Wisconsin Card Sorting Test Computerised Version, the Comprehensive Trail Making Test, the Brixton Spatial Anticipation Test, the Rey Complex Figure and the Group Embedded Figures Test.

RESULTS

Comparisons of the adolescents and adults with anorexia nervosa revealed no significant differences for any of the neuropsychological test scores even after adjusting for potential confounding factors. Neither cognitive flexibility nor attention to detail were associated with level of eating disorder symptomatology, depression, anxiety or obsessive-compulsive symptomatology. Unlike age, illness duration was found weakly associated with perseverative errors Wisconsin Card Sorting Test and with the central coherence index of the Rey Complex Figure recall condition.

CONCLUSIONS

Set-shifting and central coherence performance were independent of age, clinical symptoms severity and emotional status. Additional studies on the relationship between the duration of anorexia nervosa and neuropsychological difficulties are needed.

Do orthorexia and intolerance of uncertainty mediate the relationship between autism spectrum traits and disordered eating symptoms?

PURPOSE

Autism spectrum disorder traits have been implicated in the psychopathology of eating disorders and may also be relevant for the development of orthorexia symptoms. Further, intolerance of uncertainty (IUS) may indirectly contribute to the development of disordered eating, as the displacement of anxiety onto food may help achieve a sense of control and maximise certainty. We examined a new cognitive model of eating pathology which assessed the role of IU and orthorexia symptoms as potential mediators of the relationship between autistic traits and disordered eating in a community sample.

METHODS

Three-hundred-and-ninety-six female participants (M = 20.07, SD = 4.52 years old) completed an online self-report questionnaire which assessed the variables of interest.

RESULTS

Despite finding significant bivariate correlations, our model results showed that autistic traits did not directly predict disordered eating or orthorexia symptoms. Significant indirect relationships were found between autistic traits and eating disorder symptoms through both IU and orthorexia symptoms.

CONCLUSION

The findings provide partial support for our proposed model suggesting that autistic traits may increase the vulnerability for disordered eating, not directly, but through their associations with mechanisms such as IU and the development of problematic eating behaviours typical of orthorexia. Future research should focus on whether targeting IU may assist in preventing the development of disordered eating.

LEVEL OF EVIDENCE

Level V, cross-sectional descriptive study.

Exploring neuropsychological and socio-emotional task performance in anorexia nervosa: A cluster analytic approach

OBJECTIVE

The aim of this study was to characterise heterogeneity in neuropsychological and socio-emotional task performance in young women with anorexia nervosa (AN) using hierarchical cluster analysis. Further, we aimed to test whether cognitive profiles were associated with differences in clinical variables (body mass index, illness duration and age at diagnosis), psychopathology (eating disorder, autistic symptoms, anxiety and depression) and functional impairment.

METHOD

Set-shifting, central coherence and theory of mind abilities were measured in 118 women with acute or remitted AN. A hierarchical cluster analysis using Ward's method with a Euclidean distance measure was performed with the neuropsychological and socio-emotional variables. Differences between clusters were assessed using ANOVAs.

RESULTS

Four clusters emerged, with significant differences in neuropsychological and socio-emotional task performance. There were no significant differences between clusters in clinical variables, psychopathology or functional impairment, however, these analyses lacked power due to small cluster sizes.

CONCLUSIONS

Our results demonstrate significant heterogeneity in cognitive profiles in AN, supporting a more personalised approach to treatment. Studies in larger samples are required to establish whether these variables map onto clinically significant differences in aetiology, clinical presentation, comorbidity patterns and/or treatment responses.

Subjective cognitive rigidity and attention to detail: A cross-cultural validation of the Detail and Flexibility Questionnaire (DFlex) in a French clinical sample

Introduction: People diagnosed with Anorexia Nervosa (AN) are at risk for poor cognitive flexibility and excessive attention to detail. These difficulties are traditionally quantified using neuropsychological tests. These tests do not capture the subjective repercussions of these cognitive styles. The Detail and Flexibility Questionnaire (DFlex) has been specifically developed to measure these repercussions. The aim of this study was to evaluate the psychometric properties of the French version of this scale (F-DFlex) and to adapt it if needed. Methods: The instrument factor structure, internal consistency, convergent, and discriminant validity were assessed in a sample of 107 French women AN inpatients. For convergent validity, associations between F-DFlex scores, perceived levels of autistic traits (Autism Quotient questionnaire - AQ) and eating disorders symptomatology (Eating Disorder Examination Questionnaire - EDE-Q), as well as neuropsychological evaluations (Wisconsin Card Sorting Test - WCST, Rey Complex Figure - RCF) were tested. Discriminant validity was assessed by comparing F-DFlex scores of the patients with a chronic versus non-chronic illness. Results: The results of the exploratory factorial analysis led to the removal of four items. Internal consistency indices of this shortened version were good. Correlation coefficients directions and values between F-DFlex factors and relevant AQ Switching and Detail subscores were satisfactory, indicating good convergent validity. F-DFlex Rigidity scores were associated with the WCST percentage of perseverative errors, but the F-DFlex Attention to Detail scores were not associated with the RCF central coherence index. F-DFlex scores were associated with the severity of eating disorders symptomatology independently of BMI, illness duration, or anxiety, and depression. Conclusion: This study indicates good psychometric properties of this new version of the DFlex. The F-DFlex appears as a promising self-report screening tool of important cognitive dimensions for use in clinical management of people diagnosed with AN.

Alexithymia may explain the relationship between autistic traits and eating disorder psychopathology

BACKGROUND

Autistic people are disproportionately vulnerable to anorexia nervosa and other eating disorders (ED), and within the general population, autistic traits correlate with ED psychopathology. A putative mechanism which may underpin this heightened risk is alexithymia, a difficulty identifying and describing emotional states which is observed in both autism and ED. In two experiments with independent non-clinical samples, we explored whether alexithymia might mediate the heightened risk of eating psychopathology in individuals high in autistic traits.

METHODS

Our first experiment used the PROCESS macro for SPSS to examine relationships between alexithymia (measured by the Toronto Alexithymia Scale (TAS-20)), autistic traits (autism quotient (AQ)), and eating psychopathology (Eating Attitudes Test (EAT-26)) in 121 participants. Our second experiment (n = 300) replicated and furthered this analysis by examining moderating effects of sex and controlling for anxiety and depression as covariates. We also included an additional performance-based measure of alexithymia, the Levels of Emotional Awareness Scale (LEAS).

RESULTS

Study 1 suggested that TAS-20 scores mediated the relationship between heightened autistic traits and eating psychopathology. Replication and further scrutiny of this finding, in study 2, revealed that this mediation effect was partial and specific to the female participants in this sample. The mediation effect appeared to be carried by the difficulty identifying feelings subscale of the TAS-20, even when depression and anxiety were controlled for. LEAS scores, however, were not significantly related to autistic traits or eating psychopathology.

LIMITATIONS

Cross-sectional data prevents any conclusions around the direction and causality of relationships between alexithymia, autistic traits, and eating psychopathology (alongside depression and anxiety), necessitating longitudinal research. Our non-clinical sample was predominantly Caucasian undergraduate students, so it remains to be seen if these results would extrapolate to clinical and/or autistic samples. Divergence between the TAS-20 and LEAS raises crucial questions regarding the construct validity of these measures.

CONCLUSIONS

Our findings with respect to autistic traits suggest that alexithymia could partially explain the prevalence of ED in autistic people and may as such be an important consideration in the pathogenesis and treatment of ED in autistic and non-autistic people alike. Further research with clinical samples is critical to explore these ideas. Differences between men and women, furthermore, emphasize the importance of looking for sex-specific as well as generic risk factors in autistic and non-autistic men and women.

Characteristics of autism spectrum disorders are associated with longer duration of anorexia nervosa: A systematic review and meta-analysis

OBJECTIVE

Anorexia nervosa (AN) is associated with neuropsychological characteristics such as impairments in central coherence, cognitive flexibility, and emotion recognition. The same features also manifest in autism spectrum disorders (ASD) and have been suggested to be associated with illness prolongation in AN. The purpose of this meta-analysis was to examine whether pronounced neuropsychological characteristics related to ASD are associated with illness duration in AN.

METHOD

Four databases (Medline, PsycINFO, Scopus, PubMed) were searched for eligible studies. Search terms were (a) "anorexia nervosa" and (b) "cognitive flexibility" or "set-shifting" or "central coherence" or "emotion recognition" or "theory of mind". The final sample consisted of 53 studies. Duration of AN was divided into three categories in order to investigate differences between the groups with varying illness duration. The meta-analysis was performed with Review Manager using a random-effects model.

RESULTS

Deficits in central coherence, cognitive flexibility, and emotion recognition were pronounced among individuals with prolonged AN compared to those with shorter illness duration.

DISCUSSION

A prolonged course of AN appears to be associated with underlying neuropsychological characteristics that are also distinctive to ASD. Neuropsychological impairments may lead to prolonged AN, and prolonged illness may contribute to the subsequent "neurological scar effect," further strengthening these impairments.

Prominent autistic traits and subthreshold bipolar/mixed features of depression in severe anorexia nervosa

OBJECTIVE

Autistic traits are associated with a burdensome clinical presentation of anorexia nervosa (AN), as is AN with concurrent depression. The aim of the present study was to explore the intertwined association between complex psychopathology combining autistic traits, subthreshold bipolarity, and mixed depression among people with AN.

METHOD

Sixty patients with AN and concurrent major depressive episode (mean age, 22.2±7 years) were cross-sectionally assessed using the Autism-Spectrum Quotient test (AQ-test), the Hamilton depression scales for depression and anxiety, the Young Mania Rating Scale (YMRS), the Hypomania-Checklist-32 (HCL-32), second revision (for subthreshold bipolarity), the Brown Assessment and Beliefs Scale (BABS), the Yale-Brown-Cornell Eating Disorders Scale (YBC-EDS), and the Eating Disorder Examination Questionnaire (EDE-Q). Cases were split into two groups depending on body mass index (BMI): severe AN (AN+) if BMI < 16, not severe (AN-) if BMI ≥ 16.

RESULTS

The "subthreshold bipolarity with prominent autistic traits" pattern correctly classified 83.6% of AN patients (AN+ = 78.1%; AN- = 91.3%, Exp(B) = 1.391). AN+ cases showed higher rates of positive scores for YMRS items 2 (increased motor activity-energy) and 5 (irritability) compared to AN- cases.

CONCLUSIONS

In our sample, depressed patients with severe AN had more pronounced autistic traits and subtly mixed bipolarity. Further studies with larger samples and prospective follow-up of treatment outcomes are warranted to replicate these findings.

Sex-Gender Comparisons in Comorbidities of Children and Adolescents With High-Functioning Autism Spectrum Disorder

Over the last few years, new studies focused their attention on the gender-related features in high-functioning autism spectrum disorder (HFA), often leading to controversial results. Another interesting aspect of these subtype of patients is linked to the complexity of clinical presentation, where besides core symptoms, other co-occurrence disorders may complicate the diagnostic evaluation. Therefore, we retrospectively studied 159 HFA patients, male and female, investigating their comorbidities and to find any gender difference. For each patient, were evaluated the presence/absence, type and gender distribution of psychopathological comorbidities, according to DSM-5 diagnostic criteria. The total sample was divided in 100 male and 59 female patients, age and intelligence quotient matched. In our sample, the psychiatric comorbidities observed were Attention Deficit Hyperactivity Disorder, Anxiety Disorders, Depressive Disorders, Bipolar Disorder, Obsessive-Compulsive Disorder, and Anorexia Nervosa. No statistical significant differences were found between male and female HFA patients comorbidities except for Anorexia Nervosa. In both male and female patients, attention deficit and hyperactivity disorder and anxiety disorders were found in high percentage. In conclusion, our investigation showed that a statistical significant difference of comorbidity between male and female HFA patients was found only for AN diagnosis. However, the question about the distinction between female and male HFA patients remains quite interesting and an open area of research for future studies.

An exploration of the association between matrix reasoning and eating disturbance behavior in girls with autism spectrum disorder

Background

Although there have been suggestions that central coherence may be associated with eating disturbances (EBD) in children with autism spectrum disorder (ASD), relatively little attention has been given to specific aspects of IQ and EDB.

Methods

The association between total IQ, perceptual and verbal composite scores and subtests was explored in a sample of 50 high-functioning girls with ASD (mean age = 9.7 years, SD = 2.4 years, range = 6 years to 14 years). Self-reports and mothers' reports were collected about the girls' EDB.

Results

There were only isolated associations between mothers' data and the girls' IQ. Selected aspects of the girls' self-reported EDB were significantly associated with matrix reasoning.

Conclusion

The role of IQ, particularly matrix reasoning, in the assessment and treatment of EDB in girls with ASD, is highlighted by these findings.