What can cognitive neuroscience teach us about anorexia nervosa?

Histone deacetylase 4 (HDAC4): a new player in anorexia nervosa?

Anorexia nervosa (AN) and other eating disorders continue to constitute significant challenges for individual and public health. AN is thought to develop as a result of complex interactions between environmental triggers, psychological risk factors, sociocultural influences, and genetic vulnerability. Recent research developments have highlighted a novel potentially relevant component in the AN etiology-activity of the histone deacetylase 4 (HDAC4) gene that has emerged in several recent studies related to AN. HDAC4 is a member of the ubiquitously important family of epigenetic modifier enzymes called histone deacetylases and has been implicated in processes related to the formation and function of the central nervous system (CNS), bone, muscle, and metabolism. In a family affected by eating disorders, a missense mutation in HDAC4 (A786T) was found to segregate with the illness. The relevance of this mutation in eating-related behaviors was further confirmed with mouse models. Despite  the fact that HDAC4 has not been identified as a significant signal in genome-wide association studies in AN, several studies have found significant or near-significant methylation differences in HDAC4 locus in peripheral tissues of actively ill AN patients in comparison with different control groups. Limitations of these studies include a lack of understanding of to what extent the changes in methylation are predictive of AN as such changes might also occur as a consequence of the disease. It remains to be determined how methylation in peripheral tissues correlates with that in the CNS and how different methylation patterns affect HDAC4 expression. The present review discusses the findings and potential roles of HDAC4 in AN. Its emerging roles in learning and neuroplasticity may be specific and relevant for the etiology of AN and potentially lead to novel therapeutic approaches.

The improvement in neurocognitive functioning in anorexia nervosa adolescents throughout the integrative model of psychotherapy including cognitive remediation therapy

BACKGROUND

Patients with anorexia nervosa (AN) experience difficulties in neurocognitive functioning in the acute phase of illness which might be related to clinical presentation, but also in the apparently remitted state after weight recovery. Among the most commonly reported persistent deficits is cognitive inflexibility, which can be interpreted as a vulnerability trait or a "neuropsychological scar" reflecting the detrimental effect of prolonged semi-starvation in patients with a long duration of illness. Studies of adolescent samples with a relatively short clinical course may enable avoiding the effect of prolonged illness and help to determine whether neuropsychological deficits are trait or state dependent. The aim of this study is to assess cognitive functioning in adolescents with AN before and after the inpatient treatment programme, including cognitive remediation therapy (CRT).

METHODS

Forty-seven adolescent female inpatients with AN diagnosed according to DSM-5 and fifty healthy female adolescents matched for the education level and age were recruited. The patients underwent a multimodal treatment including a ten-week CRT. The standardized and cross-validated neuropsychological (Trail Making Test - TMT A and B, Color-Word Stroop Task - CWST, Ruff Figural Fluency Test - RFFT) and clinical measurements (Beck Depression Inventory - BDI, Eating Attitude Test - EAT-26, Yale-Brown Obsessive Compulsive Scale - Y-BOCS) were used to assess both clinical (in the acute phase and after partial weight recovery) and control subjects.

RESULTS

Initially, AN patients performed significantly worse compared to the controls, but afterwards, inpatient treatment improvement was noted on all examined measures. In a few subtests (TMT, CWST) performance of AN patients after the programme was still significantly poorer than in HC.

CONCLUSIONS

Cognitive inflexibility in adolescent AN patients, as measured with TMT, CWST, and RFFT tends to improve after therapy. Nevertheless, a few neuropsychological subtests which did not show complete normalization may warrant attention in subsequent studies. Further research including control intervention is needed to conclude whether CRT intervention affects the outcome.

Executive functioning in adolescent anorexia nervosa: Neuropsychology versus self- and parental-report

There is limited research concerning the relationship between neuropsychological assessment and self-report of executive functioning in adolescent anorexia nervosa (AN); available studies demonstrate only low to moderate correlations. Therefore, this study examines the association between neuropsychological test performance and self-report in AN. Forty adolescent inpatients with AN completed an extensive neuropsychological assessment, including set-shifting, central coherence, and questionnaires assessing executive functioning in daily life (BRIEF-SR). Their parents filled out an analog version (BRIEF-PF). Statistical analyses revealed low to medium positive and negative correlations between neuropsychological measures and BRIEF subscales. Similarly, self- and parental ratings were only slightly positively correlated, with patients scoring significantly higher than their parents on two subscales. The results support previous findings of modest correlations between self-report and performance-based testing and emphasize the importance of a multiple format assessment of executive functioning in adolescent AN.

How certainty appraisal might improve both body dissatisfaction and body overestimation in anorexia nervosa: a case report

BACKGROUND

Patients with anorexia nervosa often report a conscious alteration of body image representation, with both body overestimation and body dissatisfaction. Cognitive and behavioural therapy is effective for treating many psychiatric disorders but often fails to treat anorexia nervosa and body image distortions. Although patients are aware of their weight loss, they continue to feel overweight - as if there were a conflict between a previous (maybe already false) body representation and the new one. These distortions are linked to negative emotions focused on the body but which can extend to the self (e.g. disgust and sadness).

CASE PRESENTATION

The present case report is the first in which the Appraisal Tendency Framework has been applied to decrease body image distortions in a patient with anorexia nervosa. The Appraisal Tendency Framework is usually used to understand how emotions influence decision making. Here, we report on a 24-year-old woman who suffered from anorexia nervosa and body image distortions, and was treated as an inpatient with conventional cognitive and behavioural therapy for an eating disorder. Body image distortions were assessed before and after the patient completed an adaptation of the Iowa Gambling Task, coupled with the induction of a heuristic processing emotion. We hypothesized that allowing the patient to focus on the emotional cues in the modified Iowa Gambling Task would improve her decisions about her true body shape.

CONCLUSION

All body image measures were improved after the protocol. Consequently, we suggest that the Appraisal Tendency Framework might be a valuable means of investigating body image issues in eating disorders and anorexia nervosa. Further studies are required to expand and detail these findings.

Associations between neural correlates of visual stimulus processing and set-shifting in ill and recovered women with anorexia nervosa

Women ill with anorexia nervosa (AN) have been shown to exhibit altered cognitive functioning, particularly poor set-shifting (SS). In this study, we investigated whether brain activation in frontal and parietal regions during visual stimulus processing correlates with SS ability. Women currently ill with AN (AN; N=14), recovered women (REC; N=14) and healthy controls (HC; N=15), viewed alternating blocks of food and non-food pictures during functional magnetic resonance imaging (fMRI). The Berg's Card Sorting Task was completed outside the scanner to measure SS. A priori regions of interest (ROIs) were defined in frontal and parietal regions. The activation during visual stimulus processing in several ROIs correlated positively with poor SS ability in REC, particularly in the left dorsal anterior cingulate cortex (dACC). The correlations with poor SS ability were opposite in AN patients, particularly in the right dACC. These findings underscore that addressing heightened levels of cognitive control associated with higher frontal activation could reduce cognitive inflexibility in recovered women. In AN, greater activation in frontal and parietal regions might be necessary to perform at normal levels during various tasks. Thus, weight restoration could be necessary for AN patients prior to addressing cognitive inflexibility.

Reduced functional connectivity in the thalamo-insular subnetwork in patients with acute anorexia nervosa

The neural underpinnings of anorexia nervosa (AN) are poorly understood. Results from existing functional brain imaging studies using disorder-relevant food- or body-stimuli have been heterogeneous and may be biased due to varying compliance or strategies of the participants. In this study, resting state functional connectivity imaging was used. To explore the distributed nature and complexity of brain function we characterized network patterns in patients with acute AN. Thirty-five unmedicated female acute AN patients and 35 closely matched healthy female participants underwent resting state functional magnetic resonance imaging. We used a network-based statistic (NBS) approach [Zalesky et al., 2010a] to identify differences between groups by isolating a network of interconnected nodes with a deviant connectivity pattern. Group comparison revealed a subnetwork of connections with decreased connectivity including the amygdala, thalamus, fusiform gyrus, putamen and the posterior insula as the central hub in the patient group. Results were not driven by changes in intranodal or global connectivity. No network could be identified where AN patients had increased coupling. Given the known involvement of the identified thalamo-insular subnetwork in interoception, decreased connectivity in AN patients in these nodes might reflect changes in the propagation of sensations that alert the organism to urgent homeostatic imbalances and pain-processes that are known to be severely disturbed in AN and might explain the striking discrepancy between patient's actual and perceived internal body state.

A systematic review of the effects of neuromodulation on eating and body weight: evidence from human and animal studies

BACKGROUND

Eating disorders (ED) are chronic and sometimes deadly illnesses. Existing treatments have limited proven efficacy, especially in the case of adults with anorexia nervosa (AN). Emerging neural models of ED provide a rationale for more targeted, brain-directed interventions.

AIMS

This systematic review has examined the effects of neuromodulation techniques on eating behaviours and body weight and assessed their potential for therapeutic use in ED.

METHOD

All articles in PubMed, PsychInfo and Web of Knowledge were considered and screened against a priori inclusion/exclusion criteria. The effects of repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation, vagus nerve stimulation (VNS) and deep brain stimulation (DBS) were examined across studies in ED samples, other psychiatric and neurological disorders, and animal models.

RESULTS

Sixty studies were identified. There is evidence for ED symptom reduction following rTMS and DBS in both AN and bulimia nervosa. Findings from studies of other psychiatric and neurological disorders and from animal studies demonstrate that increases in food intake and body weight can be achieved following DBS and that VNS has potential value as a means of controlling eating and inducing weight loss.

CONCLUSIONS

Neuromodulation tools have potential for reducing ED symptomatology and related behaviours, and for altering food intake and body weight. In response to such findings, and emerging neural models of ED, treatment approaches are highly unlikely to remain 'brainless'. More research is required to evaluate the potential of neuromodulation procedures for improving long-term outcomes in ED.