Structural magnetic resonance imaging in eating disorders: a systematic review of voxel-based morphometry studies

Genetic polymorphisms and their association with neurobiological and psychological factors in anorexia nervosa: a systematic review

Background and aims

Anorexia nervosa (AN) is a complex neuropsychiatric disorder. This systematic review synthesizes evidence from diverse studies to assess and investigate the association between gene polymorphisms and psychological and neurobiological factors in patients with AN.

Methods

A systematic search across PubMed, PsycINFO, Scopus, and Web of Science databases, along with manual searching, was conducted. The review protocol was approved by PROSPERO (CRD42023452548). Out of 1,250 articles, 11 met the inclusion criteria. The quality of eligible articles was assessed using the Newcastle-Ottawa Scale (NOS) tool. The systematic review followed the PRISMA guidelines.

Results

The serotoninergic system, particularly the 5-HTTLPR polymorphism, is consistently linked to altered connectivity in the ventral attention network, impaired inhibitory control, and increased susceptibility to AN. The 5-HTTLPR polymorphism affects reward processing, motivation, reasoning, working memory, inhibition, and outcome prediction in patients with AN. The dopaminergic system, involving genes like COMT, DRD2, DRD3, and DAT1, regulates reward, motivation, and decision-making. Genetic variations in these dopaminergic genes are associated with psychological manifestations and clinical severity in patients with AN. Across populations, the Val66Met polymorphism in the BDNF gene influences personality traits, eating behaviors, and emotional responses. Genes like OXTR, TFAP2B, and KCTD15 are linked to social cognition, emotional processing, body image concerns, and personality dimensions in patients with AN.

Conclusion

There was an association linking multiple genes to the susceptibly and/or severity of AN. This genetic factor contributes to the complexity of AN and leads to higher diversity of its clinical presentation. Therefore, conducting more extensive research to elucidate the underlying mechanisms of anorexia nervosa pathology is imperative for advancing our understanding and potentially developing targeted therapeutic interventions for the disorder.Systematic review registration: [https://clinicaltrials.gov/], identifier [CRD42023452548].

Differential alterations of amygdala nuclei volumes in acutely ill patients with anorexia nervosa and their associations with leptin levels

BACKGROUND

The amygdala is a subcortical limbic structure consisting of histologically and functionally distinct subregions. New automated structural magnetic resonance imaging (MRI) segmentation tools facilitate the in vivo study of individual amygdala nuclei in clinical populations such as patients with anorexia nervosa (AN) who show symptoms indicative of limbic dysregulation. This study is the first to investigate amygdala nuclei volumes in AN, their relationships with leptin, a key indicator of AN-related neuroendocrine alterations, and further clinical measures.

METHODS

T1-weighted MRI scans were subsegmented and multi-stage quality controlled using FreeSurfer. Left/right hemispheric amygdala nuclei volumes were cross-sectionally compared between females with AN (n = 168, 12-29 years) and age-matched healthy females (n = 168) applying general linear models. Associations with plasma leptin, body mass index (BMI), illness duration, and psychiatric symptoms were analyzed via robust linear regression.

RESULTS

Globally, most amygdala nuclei volumes in both hemispheres were reduced in AN v. healthy control participants. Importantly, four specific nuclei (accessory basal, cortical, medial nuclei, corticoamygdaloid transition in the rostral-medial amygdala) showed greater volumetric reduction even relative to reductions of whole amygdala and total subcortical gray matter volumes, whereas basal, lateral, and paralaminar nuclei were less reduced. All rostral-medially clustered nuclei were positively associated with leptin in AN independent of BMI. Amygdala nuclei volumes were not associated with illness duration or psychiatric symptom severity in AN.

CONCLUSIONS

In AN, amygdala nuclei are altered to different degrees. Severe volume loss in rostral-medially clustered nuclei, collectively involved in olfactory/food-related reward processing, may represent a structural correlate of AN-related symptoms. Hypoleptinemia might be linked to rostral-medial amygdala alterations.

Can neuroimaging measures differentiate the disease course of anorexia nervosa? A systematic review

Anorexia nervosa (AN) entails many uncertainties regarding the clinical outcome, due to large heterogeneity in the disease course. AN is associated with global decrease in brain volumes and altered brain functioning during acute illness. However, it is unclear whether structural and functional brain alterations can predict clinical outcome. We aimed to systematically review the predictive value of volumetric and functional brain outcome measures of structural and functional brain magnetic resonance imaging (MRI) on the disease course of AN. Four databases (Embase, Medline, Psycinfo, and Cochrane Central Register) were systematically searched. A total of 15 studies (structural MRI: n = 6, functional MRI: n = 9) were reviewed. In total 464 unique AN patients, and 328 controls were included. Follow-up time ranged between 1 and 43 months. Structural neuroimaging studies showed that lower brain volumes of the cerebellum, subcortical grey matter, and cortical white matter at admission predicted a worse clinical outcome. A smaller increase of the anterior cingulate cortex volume in the early phase of the disease predicted a worse clinical outcome. Lower overall gyrification, and a higher clustering coefficient predicted a worse clinical outcome. Functional MRI studies showed that frontal, parietal and temporal activity during task-based algorithms predicted follow-up body mass index, although results were bidirectional possibly due to the large heterogeneity in methodological approaches. Neuroimaging measures may predict the clinical outcome of AN. However, there is a lack of replication studies. Future studies are needed to validate the prognostic utility of neuroimaging measures in AN patients, and should harmonize demographic, clinical and neuroimaging features in order to enhance comparability.

The cerebellum gains weight: A systematic review of alterations in cerebellar volume and cerebro-cerebellar functional alterations in individuals with eating disorders

BACKGROUND

Brain imaging studies on eating disorders (EDs) often reported volumetric and functional changes involving the cerebellum. Nevertheless, few studies performed in-depth examinations and suggested a cerebellar role in the EDs' pathophysiology.

METHODS

A systematic literature search on volumetric changes and functional alterations involving the cerebellum in individuals with EDs was conducted using PubMed, PsychInfo and Web of Science. This review was conducted according to the Preferred Reporting Items for Systematic Reviews (PRISMA) statement and Rayyan web application for screening studies.

RESULTS

Twenty-four papers reporting cerebellar alterations in individuals with EDs were included in the study: 9 assessing brain volumetric changes, 9 investigating task-based functional brain activation and 6 investigating brain functional connectivity at rest. Most studies focused on anorectic-type EDs (n.22), while fewer involved bulimic-type EDs (n.9) and eating disorders not otherwise specified (n.2), revealing subtypes-specific patterns of altered cerebellar volume and functionality.

CONCLUSIONS

This review proposes critical arguments to consider the cerebellum as a key structure in the pathophysiology of EDs that requires further forthcoming exploration.

Rethinking the Approach to Preclinical Models of Anorexia Nervosa

PURPOSE OF REVIEW

The goal of this review is to describe how emerging technological developments in pre-clinical animal research can be harnessed to accelerate research in anorexia nervosa (AN).

RECENT FINDINGS

The activity-based anorexia (ABA) paradigm, the best characterized animal model of AN, combines restricted feeding, excessive exercise, and weight loss. A growing body of evidence supports the idea that pathophysiological weight loss in this model is due to cognitive inflexibility, a clinical feature of AN. Targeted manipulations that recapitulate brain changes reported in AN - hyperdopaminergia or hyperactivity of cortical inputs to the nucleus accumbens - exacerbate weight loss in the ABA paradigm, providing the first evidence of causality. The power of preclinical research lies in the ability to assess the consequences of targeted manipulations of neuronal circuits that have been implicated in clinical research. Additional paradigms are needed to capture other features of AN that are not seen in ABA.

Structural brain changes in severe and enduring anorexia nervosa: A multimodal magnetic resonance imaging study of gray matter volume, cortical thickness, and white matter integrity

Whole-brain T1-weighted imaging and diffusion tensor imaging was performed in 35 adult women with anorexia nervosa (AN) and 35 healthy controls. We conducted voxel-based group comparisons for gray matter volume (GMV), cortical thickness (CT), and fractional anisotropy (FA) values, using age and total intracranial volume as nuisance covariates. We then conducted the same group comparisons for these three measures, but this time also controlled for the following global pathological measures: total GMV, mean CT across the whole brain, and mean FA across the entire white matter skeleton. Compared with the healthy controls, AN patients had lower GMV and CT in widespread cortical regions, and smaller FA values in widespread white matter regions. After controlling for global parameters, almost all of the differences between the two groups disappeared, except for higher CT in the medial orbital gyrus and parietal operculum in the AN group. Structural brain changes in AN are likely to be composed of both global and region-specific changes. The former changes are likely to have a dominant impact, while the latter changes might in part explain the disease-specific pathophysiology of AN.

Wernicke Encephalopathy in schizophrenia: a systematic review

INTRODUCTION

In schizophrenia, patients can experience delusions or hallucinations regarding their food or health status, leading to diminished intake. Fasting or not eating a balanced diet can cause neurological complications after severe vitamin B1 malnourishment. The precise signs and symptoms of Wernicke's Encephalopathy (WE) in schizophrenia are not clear. Our aim, therefore, was to conduct a systematic review of the characteristics of WE in patients with schizophrenia.

METHODS

We conducted our search from inception using Mesh terms schizophrenia, Wernicke Encephalopathy, Korsakoff's syndrome. We searched Pubmed, ISI Web of Science, and Scopus. We defined WE as mental, oculomotor, and motoric alterations and thiamine deficiency; schizophrenia was defined as psychosis, hallucinations and/or delusions; adequate WE treatment as >500 mg/day intramuscular or intravenous. Our search yielded 15 WE cases.

RESULTS

WE is characterised by a triad of mental status change, ocular signs and ataxia. In alcohol use disorder, this triad is present in 16% of the cases, but 12 out of the 15 published schizophrenia cases presented themselves with a full triad. Importantly, as an additional characteristic, patients often lost weight within a short period of time.

CONCLUSIONS

The development of a full triad and additional symptomatology suggests a late recognition of signs and symptoms of WE in schizophrenia. Prophylactic thiamine checks and treatment in patients with schizophrenia are relevant, and if WE is suspected adequate parenteral thiamine supplementation is necessary.Key pointsOnly few cases of schizophrenia-related WE have been published in the literature, though challenges in diagnosing and recognising WE suggest that the vast majority of cases go undetected.Acute thiamine deficiency leads to Wernicke's Encephalopathy.Patients diagnosed with schizophrenia are at risk to develop Wernicke's Encephalopathy.Timely treatment with high doses of thiamine can adequately treat Wericke's Encephalopathy.

Neuroimaging Findings in Adolescents and Young Adults with Anorexia Nervosa: A Systematic Review

BACKGROUND

Anorexia nervosa (AN) is a serious, multifactorial mental disorder affecting predominantly young females. This systematic review examines neuroimaging findings in adolescents and young adults up to 24 years old, in order to explore alterations associated with disease pathophysiology.

METHODS

Eligible studies on structural and functional brain neuroimaging were sought systematically in PubMed, CENTRAL and EMBASE databases up to 5 October 2020.

RESULTS

Thirty-three studies were included, investigating a total of 587 patients with a current diagnosis of AN and 663 healthy controls (HC). Global and regional grey matter (GM) volume reduction as well as white matter (WM) microstructure alterations were detected. The mainly affected regions were the prefrontal, parietal and temporal cortex, hippocampus, amygdala, insula, thalamus and cerebellum as well as various WM tracts such as corona radiata and superior longitudinal fasciculus (SLF). Regarding functional imaging, alterations were pointed out in large-scale brain networks, such as default mode network (DMN), executive control network (ECN) and salience network (SN). Most findings appear to reverse after weight restoration. Specific limitations of neuroimaging studies in still developing individuals are also discussed.

CONCLUSIONS

Structural and functional alterations are present in the early course of the disease, most of them being partially or totally reversible. Nonetheless, neuroimaging findings have been open to many biological interpretations. Thus, more studies are needed to clarify their clinical significance.

Differential longitudinal changes of neuronal and glial damage markers in anorexia nervosa after partial weight restoration

Atrophic brain changes in acute anorexia nervosa (AN) are often visible to the naked eye on computed tomography or magnetic resonance imaging scans, but it remains unclear what is driving these effects. In neurological diseases, neurofilament light (NF-L) and tau protein have been linked to axonal damage. Glial fibrillary acidic protein (GFAP) has been associated with astroglial injury. In an attempt to shed new light on factors potentially underlying past findings of structural brain alterations in AN, the current study investigated serum NF-L, tau protein, and GFAP levels longitudinally in AN patients undergoing weight restoration. Blood samples were obtained from 54 acutely underweight, predominantly adolescent female AN patients and 54 age-matched healthy control participants. AN patients were studied in the severely underweight state and again after short-term partial weight restoration. Group comparisons revealed higher levels of NF-L, tau protein, and GFAP in acutely underweight patients with AN compared to healthy control participants. Longitudinally, a decrease in NF-L and GFAP but not in tau protein levels was observed in AN patients upon short-term partial weight restoration. These results may be indicative of ongoing neuronal and astroglial injury during the underweight phase of AN. Normalization of NF-L and GFAP but not tau protein levels may indicate an only partial restoration of neuronal and astroglial integrity upon weight gain after initial AN-associated cell damage processes.

Case report of anorexia nervosa showing periventricular gliosis at autopsy

Anorexia nervosa (AN) is a serious eating disorder characterized by self-starvation and extreme weight loss. It has the highest mortality rate among all psychiatric disorders. Recent research indicates that malnutrition in AN patients induces various kinds of functional brain damage, but the pathophysiology of AN remains unclear. We report here the neuropathological findings of a 31-year-old Japanese woman. At age 24, she had a fear of gaining weight and reduced her dietary intake; she had extremely low body weight associated with overeating then self-induced vomiting. She was clinically diagnosed as having AN and was admitted to a psychiatric hospital with severe depression and suicidal thoughts. At age 31, she died despite intensive physical care and psychotherapy. Neuropathological examination revealed increased capillary blood vessels and slight fibrillary gliosis in the mammillary bodies, with similarities to Wernicke encephalopathy. The brainstem exhibited the characteristic features of central pontine myelinolysis, characterized by a sharply demarcated region of myelin pallor and relative sparing of axons. Senile changes, including neurofibrillary tangles/senile plaques, were not significant. Severe fibrillary gliosis was prominent around periventricular regions, including the caudate nucleus and nucleus accumbens, which are associated with cognition, emotion, and emotional behaviors via the dopaminergic pathways. These findings indicate that prolonged malnutrition in AN patients may induce brain damage, leading to dysfunction of the reward-related dopaminergic pathways. Furthermore, they represent the first pathological evidence that dysfunction of the cortico-limbic-striatal circuitry is involved in the pathophysiology of psychiatric symptoms in AN patients.

Associations of age, body mass index and biochemical parameters with brain morphology in patients with anorexia nervosa

OBJECTIVE

Accumulating evidence shows that patients with anorexia nervosa (AN) have globally reduced brain mass, including lower cortical volume and thickness, which largely normalizes following weight restoration. The underlying mechanisms for these processes are unknown, and how age and severity of emaciation are associated with brain morphology in AN is poorly understood. We investigated associations of age, body mass index (BMI) and biochemical parameters with brain morphology among patients in treatment.

METHOD

We included 85 patients (94% female) aged 12-48 (mean = 23) years with quality controlled magnetic resonance imaging (MRI) data. T1-weighted MRI images, clinical characteristics and biochemical parameters were retrospectively collected from hospital records. Brain morphology was measured using FreeSurfer, and associations investigated using regression models and correlations.

RESULTS

Controlling for BMI, age showed significant associations with brain morphology generally concordant with typical brain developmental patterns. Controlling for age, BMI showed significant positive associations with cortical volume and thickness. There were no significant interaction effects between age and BMI. None of the biochemical parameters correlated significantly with brain morphology.

CONCLUSION

Our findings suggest the presence of typical neurodevelopmental patterns in AN. Importantly, we showed that severity of emaciation is related to brain morphology reductions, underscoring the importance of weight restoration.

Between wellness, relapse, and remission: Stages of illness in anorexia nervosa

OBJECTIVE

Psychiatric illnesses, like medical illnesses, can sometimes be considered as progressing through stages. Understanding these stages can lead to a better understanding of pathophysiology, and clarification of prognosis and treatment needs. Opinions from experts in the field of anorexia nervosa (AN) were sought to create a model of stages of illness.

METHOD

The Delphi approach was used to achieve consensus from a panel of 31 individuals from a range of disciplines with expertise in AN. Over three iterative rounds, participants rated agreement with statements about an overall staging framework and definitions of specific stages.

RESULTS

Agreement was reached about a longitudinal progression including Subsyndromal, Full Syndrome, Persistent Illness, and Partial and Full Remission. The panel achieved consensus in defining Subsyndromal AN as characterized by body image disturbance and mild to moderate restrictive eating. Overall, there was consensus that restrictive eating is central to the behavioral features of all stages of AN, and agreement that its absence is essential to any stage of health. There was little consensus about biological markers, other than body mass index, and no consensus about quality of life indices associated with different stages.

DISCUSSION

This panel discussion yielded an expert-informed staging model for AN. This model now needs to be tested for its validity. The lack of consensus in several areas highlighted other research questions to address in order to develop an empirically valid and scientifically useful model of the progression of AN.

Age influences structural brain restoration during weight gain therapy in anorexia nervosa

Neuroimaging studies on anorexia nervosa (AN) have consistently reported globally reduced gray matter in patients with acute AN. While first studies on adolescent AN patients provide evidence for the reversibility of these impairments after weight gain, longitudinal studies with detailed regional analysis for adult AN patients are lacking and factors associated with brain restitution are poorly understood. We investigated structural changes in anorexia nervosa using T1-weighted magnetic resonance images with surface-based morphometry. The sample consisted of 26 adult women with severe AN and 30 healthy controls. The longitudinal design comprised three time points, capturing the course of weight-restoration therapy in AN patients at distinct stages of weight gain (BMI ≤ 15.5 kg/m²; 15.5 < BMI < 17.5 kg/m²; BMI ≥ 17.5 kg/m²). Compared to controls, AN patients showed globally decreased cortical thickness and subcortical volumes at baseline. Linear mixed effect models revealed the reversibility of these alterations, with brain restoration being most pronounced during the first half of treatment. The restoration of cortical thickness of AN patients negatively correlated with age, but not duration of illness. After weight restoration, residual group differences of cortical thickness remained in the superior frontal cortex. These findings indicate that structural brain alterations of adult patients with severe AN recuperate independently of the duration of illness during weight-restoration therapy. The temporal pattern of brain restoration suggests a decrease in restoration rate over the course of treatment, with patients' age as a strong predictor of brain restitution, possibly reflecting decreases of brain plasticity as patients grow older.

Contraception in adolescents with anorexia nervosa. Is there evidence for a negative impact of combined hormonal contraceptives on bone mineral density and the course of the disease?

Objective: Adolescents with anorexia nervosa (AN) are at increased risk of unplanned pregnancies and bone loss, due to low oestrogen levels and low use of efficient contraception. The negative impact of combined hormonal contraceptives (CHC) on peak bone mass during adolescence might limit wider use in anorexic women. Another issue limiting CHC use is the concern, that CHC-induced cyclic bleeding reduces the motivation for further weight gain and thus exerts a negative impact on recovery. We wanted to find evidence based answers about the impact of CHC use on bone health and course of the disease in adolescents with AN.Methods: We performed a narrative review of the current literature investigating the effect of CHC or progestin-only contraceptives on bone density, body shape and course of disease in young women with anorexia.Results: There is no evidence that CHC use aggravates the bone loss associated with AN. In long-term users CHC exert a protective effect. Anorexic women using CHC showed at least the same or a greater weight gain in comparison with controls. Eating disorder attitudes did not worsen.Conclusion: We conclude, that at present there is no evidence, that use of CHC by AN patients has a negative impact on bone density or the course of disease.

Lower gray matter volumes of frontal lobes and insula in adolescents with anorexia nervosa restricting type: Findings from a Brain Morphometry Study

BACKGROUND

Brain atrophy in anorexia nervosa (AN) is one of the most marked structural brain changes observed in mental disorders. In this study, we propose a whole brain analysis approach to characterize global and regional cerebral volumes in adolescents with restricting-type anorexia nervosa (AN-r).

METHODS

A total of 48 adolescent females (age range 13-18 years) were enrolled in the study (24 right-handed AN-r in the early stages of the illness and treated in the same clinical setting and 24 age-matched healthy controls [HC]). High-resolution T1-weighted magnetic resonance images were acquired. Cerebral volumes, including the total amounts of gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) were obtained with the Statistical Parametric Mapping software (SPM8); specific cortical regional volumes were computed by applying an atlas-based cortical parcellation to the SPM8 GM segments. Analysis of variance (ANOVA) was performed to identify any significant between-group differences in global and regional brain volumes.

RESULTS

The analyses revealed reduced total GM volumes (p = 0.02) and increased CSF (p = 0.05) in AN-r, compared with HC. No significant between-group difference was found in WM volumes. At the regional level, significantly lower GM volumes in both frontal lobes (p = 0.006) and in the left insula (p = 0.016) were detected. No significant relationships were found between cerebral volumes and duration of illness, psychiatric comorbidities, psychopharmacological treatment, prepubertal phase, or presence of amenorrhea.

CONCLUSIONS

The topographic distribution of GM reduction in a homogenous group of AN-r involves regions responsible for the emotional and cognitive deficits associated with the illness. These findings are discussed in relation to the roles of the insular cortex and the frontal lobes.

Evidence for a sex-specific contribution of polygenic load for anorexia nervosa to body weight and prefrontal brain structure in nonclinical individuals

Genetic predisposition and brain structural abnormalities have been shown to be involved in the biological underpinnings of anorexia nervosa (AN). Prefrontal brain regions are suggested to contribute through behavioral inhibition mechanisms to body weight. However, it is unknown if and to which extent biological correlates for AN might be present in individuals without clinical AN symptomatology. We therefore investigated the contribution of polygenic load for AN on body weight and prefrontal brain structure in a sample of n = 380 nonclinical individuals. A polygenic score (PGS) reflecting the individual genetic load for the trait of anorexia nervosa was calculated. Structural MRI data were acquired and preprocessed using the cortical parcellation stream of FreeSurfer. We observed a significant PGS × sex interaction effect on body mass index (BMI), which was driven by a negative correlation between PGS and BMI in female participants. Imaging analyses revealed significant interaction effects of sex  × PGS on surface area of the lateral orbitofrontal cortex (OFC), the pars orbitalis (PO), the rostral middle frontal gyrus (RMF) and the pars triangularis (PT) of the left frontal cortex. The interaction effects were driven by positive correlations between PGS and prefrontal surface areas in female participants and negative correlations in male participants. We furthermore found sex-specific associations between BMI and left RMF surface area as well as between BMI and left PO and left RMF thickness. Our findings demonstrate a sex-specific association between polygenic load for AN, BMI, and prefrontal brain structure in nonclinical individuals. Hence, this study identifies structural abnormalities associated with polygenic load for AN and BMI in brain regions deeply involved in behavioral inhibition and impulse regulation as candidate brain regions for future research.

The promise of neurobiological research in anorexia nervosa

PURPOSE OF REVIEW

This article reviews new research in the context of existing literature to identify approaches that will advance understanding of the persistence of anorexia nervosa.

RECENT FINDINGS

Neuroscience research in anorexia nervosa has yielded disparate findings: no definitive neural mechanism underlying illness vulnerability or persistence has been identified and no clear neural target for intervention has emerged. Recent advances using structural and functional neuroimaging research, as well as new techniques for applying and combining these approaches, have led to a refined understanding of changes in neural architecture among individuals who are acutely ill, have undergone renourishment, or are in recovery/remission. In particular, advances have come from the incorporation of computational and translational approaches, as well as efforts to link experimental paradigms with illness-relevant behavior. Recent findings converge to suggest abnormalities in systems involved in reward learning and processing among individuals with anorexia nervosa.

SUMMARY

Anorexia nervosa is associated with neurobiological abnormalities. Aberrant learning and reward processing may contribute to the persistence of illness. To better utilize new techniques to understand the neural mechanisms of persistent anorexia nervosa, it may help to distinguish stages of illness and to link neurobiology with maladaptive behavior.

The Neurobiology of Eating Disorders

Eating disorders are severe psychiatric illnesses with a typical age of onset in adolescence. Brain research in youth and young adults may help us identify specific neurobiology that contributes to onset and maintenance of those disorders. This article provides a state-of-the-art review of our current understanding of the neurobiology of anorexia nervosa and bulimia nervosa. This includes brain structure and function studies to understand food restriction, binge-eating or purging behaviors, cognitive and emotional factors, as well as interoception. Binge-eating disorder and avoidant restrictive food intake disorder are also discussed, but the literature is still very small.

Altered thalamo–cortical and occipital–parietal– temporal–frontal white matter connections in patients with anorexia and bulimia nervosa: a systematic review of diffusion tensor imaging studies

BACKGROUND

Anorexia nervosa and bulimia nervosa are complex mental disorders, and their etiology is still not fully understood. This paper reviews the literature on diffusion tensor imaging studies in patients with anorexia nervosa and bulimia nervosa to explore the usefulness of white matter microstructural analysis in understanding the pathophysiology of eating disorders.

METHODS

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify diffusion tensor imaging studies that compared patients with an eating disorder to control groups. We searched relevant databases for studies published from database inception to August 2018, using combinations of select keywords. We categorized white matter tracts according to their 3 main classes: projection (i.e., thalamo–cortical), association (i.e., occipital–parietal–temporal–frontal) and commissural (e.g., corpus callosum).

RESULTS

We included 19 papers that investigated a total of 427 participants with current or previous eating disorders and 444 controls. Overall, the studies used different diffusion tensor imaging approaches and showed widespread white matter abnormalities in patients with eating disorders. Despite differences among the studies, patients with anorexia nervosa showed mainly white matter microstructural abnormalities of thalamo–cortical tracts (i.e., corona radiata, thalamic radiations) and occipital–parietal–temporal–frontal tracts (i.e., left superior longitudinal and inferior fronto-occipital fasciculi). It was less clear whether white matter alterations persist after recovery from anorexia nervosa. Available data on bulimia nervosa were partially similar to those for anorexia nervosa.

LIMITATIONS

Study sample composition and diffusion tensor imaging analysis techniques were heterogeneous. The number of studies on bulimia nervosa was too limited to be conclusive.

CONCLUSION

White matter microstructure appears to be affected in anorexia nervosa, and these alterations may play a role in the pathophysiology of this eating disorder. Although we found white matter alterations in bulimia nervosa that were similar to those in anorexia nervosa, white matter changes in bulimia nervosa remain poorly investigated, and these findings were less conclusive. Further studies with longitudinal designs and multi-approach analyses are needed to better understand the role of white matter changes in eating disorders.

White matter alterations in anorexia nervosa: Evidence from a voxel-based meta-analysis

Anorexia nervosa (AN) is a severe psychiatric disorder with a complex and poorly understood etiology. Recent studies have sought to investigate differences in white matter microstructure in AN, with significant results in several brain regions. A systematic literature search of Embase, PubMed and Psychinfo databases was conducted in order to identify Diffusion Tensor Imaging (DTI) studies of patients with AN and controls. We performed a meta-analysis of studies that met our inclusion criteria (N = 13) using effect size-signed differential mapping (AES-SDM) to detect differences in Fractional Anisotropy (FA) in patients with AN (N = 227) compared to healthy controls (N = 243). The quantitative meta-analysis of DTI studies identified decreased FA in the posterior areas of the corpus callosum, the left superior longitudinal fasciculus II, and the left precentral gyrus, as well as increased FA in the right cortico-spinal projections, and lingual gyrus in AN vs. controls. Studies of WM architecture are still limited in AN; further studies with longitudinal design are needed to better understand the complexity of abnormalities, and their persistence.

Exploration of Shared Genetic Architecture Between Subcortical Brain Volumes and Anorexia Nervosa

In MRI scans of patients with anorexia nervosa (AN), reductions in brain volume are often apparent. However, it is unknown whether such brain abnormalities are influenced by genetic determinants that partially overlap with those underlying AN. Here, we used a battery of methods (LD score regression, genetic risk scores, sign test, SNP effect concordance analysis, and Mendelian randomization) to investigate the genetic covariation between subcortical brain volumes and risk for AN based on summary measures retrieved from genome-wide association studies of regional brain volumes (ENIGMA consortium, n = 13,170) and genetic risk for AN (PGC-ED consortium, n = 14,477). Genetic correlations ranged from − 0.10 to 0.23 (all p > 0.05). There were some signs of an inverse concordance between greater thalamus volume and risk for AN (permuted p = 0.009, 95% CI: [0.005, 0.017]). A genetic variant in the vicinity of ZW10, a gene involved in cell division, and neurotransmitter and immune system relevant genes, in particular DRD2, was significantly associated with AN only after conditioning on its association with caudate volume (p_FDR = 0.025). Another genetic variant linked to LRRC4C, important in axonal and synaptic development, reached significance after conditioning on hippocampal volume (p_FDR = 0.021). In this comprehensive set of analyses and based on the largest available sample sizes to date, there was weak evidence for associations between risk for AN and risk for abnormal subcortical brain volumes at a global level (that is, common variant genetic architecture), but suggestive evidence for effects of single genetic markers. Highly powered multimodal brain- and disorder-related genome-wide studies are needed to further dissect the shared genetic influences on brain structure and risk for AN.

The potential of calibrated fMRI in the understanding of stress in eating disorders

Eating disorders (ED), including Anorexia Nervosa (AN), Bulimia Nervosa (BN), and Binge Eating Disorder (BED), are medically dangerous psychiatric disorders of unknown etiology. Accumulating evidence supports a biopsychosocial model that includes genetic heritability, neurobiological vulnerability, and psychosocial factors, such as stress, in the development and maintenance of ED. Notably, stress hormones influence appetite and eating, and dysfunction of the physiological stress response has been implicated in ED pathophysiology. Stress signals also appear associated with food reward neurocircuitry response in ED, providing a possible mechanism for the role of stress in appetite dysregulation. This paper provides a review of some of the interacting psychological, behavioral, physiological, and neurobiological mechanisms involved in the stress response among individuals with ED, and discusses novel neuroimaging techniques to address potential physiological confounds of studying neural correlates of stress in ED, such as calibrated fMRI.

Preventing Wernicke's encephalopathy in anorexia nervosa: A systematic review

Anorexia nervosa (AN) is a common eating disorder that affects 2.9 million people worldwide. Not eating a balanced diet or fasting can cause neurological complications after severe vitamin B1 malnourishment, although the precise signs and symptoms of Wernicke's encephalopathy (WE) are not clear. Our aim was to review the signs and symptoms of WE in patients with AN. We searched MEDLINE, EMBASE, Scopus, and PiCarta on all case descriptions of WE following AN. All case descriptions of WE in AN, irrespective of language, were included. Twelve WE cases were reviewed, suggesting that WE following AN is still a relatively rare neuropsychiatric disorder. WE is characterized by a triad of: mental status change, ocular signs, and ataxia. In alcoholism, this triad is present in 16% of cases, but eight out of 12 AN cases presented themselves with a full triad of symptomatology. Importantly, patients often had a more complex triad than has been previously described, involving vertigo, diplopia, and the consequences of refeeding syndrome. The development of a full triad and additional symptomatology suggests a late recognition of signs and symptoms of WE in AN. A complicating factor is the overlap between symptoms of thiamine deficiency and the symptoms of WE. Specifically, patients who show rapid weight loss are vulnerable for the development of WE. Eating disorders, such as AN, can lead to WE. Prophylactic thiamine checks and treatment in patients with AN are relevant, and in case of suspicion of WE, adequate parenteral thiamine supplementation is necessary.

Registration-based methods applied to serial high-resolution T1-weighted magnetic resonance imaging for the assessment of brain volume changes in anorexia nervosa of the restricting type

We aimed to determine whether variation in the body mass index (BMI)—a marker of anorexia nervosa (AN) severity—is associated with brain volume changes longitudinally estimated using registration-based methods on serial high-resolution T1-weighted magnetic resonance images (MRI). Fifteen female patients (mean age = 21 years; standard deviation [SD] = 5.7; range: 15–33 years) with the diagnosis of AN of the restricting type (AN-r)—according to the Diagnostic and Statistic Manual of Mental Disorders, 5^th edition criteria—underwent T1-weighted MRI at baseline and after a mean follow-up period of 11 months (SD = 6.4). We used the brain boundary shift integral (BSI) and the ventricular BSI (VBSI) to estimate volume changes after registering voxels of follow-up onto baseline MRI. Very significant and strong correlations were found between BMI variation and the brain BSI, as well as between BMI variation and the VBSI. After adjustment for age at onset, duration of illness, and the BMI rate of change before baseline MRI, the statistical significance of both associations persisted. Registration-based methods on serial MRI represent an additional tool to estimate AN severity, because they provide measures of brain volume change strongly associated with BMI variation.

Toward valid and reliable brain imaging results in eating disorders

Human brain imaging can help improve our understanding of mechanisms underlying brain function and how they drive behavior in health and disease. Such knowledge may eventually help us to devise better treatments for psychiatric disorders. However, the brain imaging literature in psychiatry and especially eating disorders has been inconsistent, and studies are often difficult to replicate. The extent or severity of extremes of eating and state of illness, which are often associated with differences in, for instance hormonal status, comorbidity, and medication use, commonly differ between studies and likely add to variation across study results. Those effects are in addition to the well-described problems arising from differences in task designs, data quality control procedures, image data preprocessing and analysis or statistical thresholds applied across studies. Which of those factors are most relevant to improve reproducibility is still a question for debate and further research. Here we propose guidelines for brain imaging research in eating disorders to acquire valid results that are more reliable and clinically useful.

Cortical thickness patterns as state biomarker of anorexia nervosa

OBJECTIVE

Only few studies have investigated cortical thickness in anorexia nervosa (AN), and it is unclear whether patterns of altered cortical thickness can be identified as biomarkers for AN.

METHOD

Cortical thickness was measured in 19 adult women with restricting-type AN, 24 individuals recovered from restricting-type AN (REC-AN) and 24 healthy controls. Those individuals with current or recovered from AN had previously shown altered regional cortical volumes across orbitofrontal cortex and insula. A linear relevance vector machine-learning algorithm estimated patterns of regional thickness across 24 subdivisions of those regions.

RESULTS

Region-based analysis showed higher cortical thickness in AN and REC-AN, compared to controls, in the right medial orbital (olfactory) sulcus, and greater cortical thickness for short insular gyri in REC-AN versus controls bilaterally. The machine-learning algorithm identified a pattern of relatively higher right orbital, right insular and left middle frontal cortical thickness, but lower left orbital, right middle and inferior frontal, and bilateral superior frontal cortical thickness specific to AN versus controls (74% specificity and 74% sensitivity, χ² p < .004); predicted probabilities differed significantly between AN and controls (p < .023). No pattern significantly distinguished the REC-AN group from controls.

CONCLUSIONS

Higher cortical thickness in medial orbitofrontal cortex and insula probably contributes to higher gray matter volume in AN in those regions. The machine-learning algorithm identified a mixed pattern of mostly higher orbital and insular, but relatively lower superior frontal cortical thickness in individuals with current AN. These novel results suggest that regional cortical thickness patterns could be state markers for AN.

Structural Neuroimaging of Anorexia Nervosa: Future Directions in the Quest for Mechanisms Underlying Dynamic Alterations

Anorexia nervosa (AN) is a serious eating disorder characterized by self-starvation and extreme weight loss. Pseudoatrophic brain changes are often readily visible in individual brain scans, and AN may be a valuable model disorder to study structural neuroplasticity. Structural magnetic resonance imaging studies have found reduced gray matter volume and cortical thinning in acutely underweight patients to normalize following successful treatment. However, some well-controlled studies have found regionally greater gray matter and persistence of structural alterations following long-term recovery. Findings from diffusion tensor imaging studies of white matter integrity and connectivity are also inconsistent. Furthermore, despite the severity of AN, the number of existing structural neuroimaging studies is still relatively low, and our knowledge of the underlying cellular and molecular mechanisms for macrostructural brain changes is rudimentary. We critically review the current state of structural neuroimaging in AN and discuss the potential neurobiological basis of structural brain alterations in the disorder, highlighting impediments to progress, recent developments, and promising future directions. In particular, we argue for the utility of more standardized data collection, adopting a connectomics approach to understanding brain network architecture, employing advanced magnetic resonance imaging methods that quantify biomarkers of brain tissue microstructure, integrating data from multiple imaging modalities, strategic longitudinal observation during weight restoration, and large-scale data pooling. Our overarching objective is to motivate carefully controlled research of brain structure in eating disorders, which will ultimately help predict therapeutic response and improve treatment.

Preserved white matter microstructure in young patients with anorexia nervosa?

A massive but reversible reduction of cortical thickness and subcortical gray matter (GM) volumes in Anorexia Nervosa (AN) has been recently reported. However, the literature on alterations in white matter (WM) volume and microstructure changes in both acutely underweight AN (acAN) and after recovery (recAN) is sparse and results are inconclusive. Here, T1-weighted and diffusion-weighted MRI data in a sizable sample of young and medication-free acAN (n = 35), recAN (n = 32), and age-matched female healthy controls (HC, n = 62) were obtained. For analysis, a well-validated global probabilistic tractography reconstruction algorithm including rigorous motion correction implemented in FreeSurfer: TRACULA (TRActs Constrained by UnderLying Anatomy) were used. Additionally, a clustering algorithm and a multivariate pattern classification technique to WM metrics to predict group membership were applied. No group differences in either WM volume or WM microstructure were detected with standard analysis procedures either in acAN or recAN relative to HC after controlling for the number of performed statistical tests. These findings were not affected by age, IQ, or psychiatric symptoms. While cluster analysis was unsuccessful at discriminating between groups, multivariate pattern classification showed some ability to separate acAN from HC (but not recAN from HC). However, these results were not compatible with a straightforward hypothesis of impaired WM microstructure. The current findings suggest that WM integrity is largely preserved in non-chronic AN. This finding stands in contrast to findings in GM, but may help to explain the relatively intact cognitive performance of young patients with AN and provide the basis for the fast recovery of GM structures. Hum Brain Mapp 37:4069-4083, 2016. © 2016 Wiley Periodicals, Inc.

Differences in regional grey matter volumes in currently ill patients with anorexia nervosa

Neurobiological findings in anorexia nervosa (AN) are inconsistent, including differences in regional grey matter volumes. Methodological limitations often contribute to the inconsistencies reported. The aim of this study was to improve on these methodologies by utilising voxel-based morphometry (VBM) analysis with the use of diffeomorphic anatomic registration through an exponentiated lie algebra algorithm (DARTEL), in a relatively large group of individuals with AN. Twenty-six individuals with AN and 27 healthy controls underwent a T1-weighted magnetic resonance imaging (MRI) scan. AN participants were found to have reduced grey matter volumes in a number of areas including regions of the basal ganglia (including the ventral striatum), and parietal and temporal cortices. Body mass index (BMI) and global scores on the Eating Disorder Examination Questionnaire (EDE-Q) were also found to correlate with grey matter volumes in a region of the brainstem (including the substantia nigra and ventral tegmental area) in AN, and predicted 56% of the variance in grey matter volumes in this area. The brain regions associated with grey matter reductions in AN are consistent with regions responsible for cognitive deficits associated with the illness including anhedonia, deficits in affect perception and saccadic eye movement abnormalities. Overall, the findings suggest reduced grey matter volumes in AN that are associated with eating disorder symptomatology.

Neuroendocrinology and brain imaging of reward in eating disorders: A possible key to the treatment of anorexia nervosa and bulimia nervosa

Anorexia nervosa and bulimia nervosa are severe eating disorders whose etiopathogenesis is still unknown. Clinical features suggest that eating disorders may develop as reward-dependent syndromes, since eating less food is perceived as rewarding in anorexia nervosa while consumption of large amounts of food during binge episodes in bulimia nervosa aims at reducing the patient's negative emotional states. Therefore, brain reward mechanisms have been a major focus of research in the attempt to contribute to the comprehension of the pathophysiology of these disorders. Structural brain imaging data provided the evidence that brain reward circuits may be altered in patients with anorexia or bulimia nervosa. Similarly, functional brain imaging studies exploring the activation of brain reward circuits by food stimuli as well as by stimuli recognized to be potentially rewarding for eating disordered patients, such as body image cues or stimuli related to food deprivation and physical hyperactivity, showed several dysfunctions in ED patients. Moreover, very recently, it has been demonstrated that some of the biochemical homeostatic modulators of eating behavior are also implicated in the regulation of food-related and non-food-related reward, representing a possible link between the aberrant behaviors of ED subjects and their hypothesized deranged reward processes. In particular, changes in leptin and ghrelin occur in patients with anorexia or bulimia nervosa and have been suggested to represent not only homeostatic adaptations to an altered energy balance but to contribute also to the acquisition and/or maintenance of persistent starvation, binge eating and physical hyperactivity, which are potentially rewarding for ED patients. On the basis of such findings new pathogenetic models of EDs have been proposed, and these models may provide new theoretical basis for the development of innovative treatment strategies, either psychological and pharmacological, with the aim to improve the outcomes of so severe disabling disorders.

Extend, Pathomechanism and Clinical Consequences of Brain Volume Changes in Anorexia Nervosa

INTRODUCTION

Brain volume deficits of grey matter (GM) and white matter (WM) are often found in patients with anorexia nervosa (AN). However, until recently, little was known about the influencing factors of these brain volume alterations, nor their exact quantification and rehabilitation.

METHODS

This review addresses these open questions and further explores what is now known about the underlying pathobiology and the clinical consequences including human studies as well as animal studies mimicking anorexia nervosa in rodents.

RESULTS

GM was reduced by 3.7% in adults and 7.6% in adolescents with AN. WM was reduced on average 2.2% in adult patients and 3.2% in adolescents. Most volume deficits in adults are reversible after long-term recovery; for adolescents, data are less clear. The main influencing factors for GM were absolute lowest weight at admission and illness duration. Cerebellar and WM reductions at admission predicted clinical outcome at one year follow-up. New studies found GABA receptor changes in GM and astrocyte loss in both GM and WM, as well as a possible role for oestrogen deficit. All three could partly explain clinical symptoms of anxiety, rigidity and learning impairments in patients with AN.

CONCLUSION

Brain volume deficits in AN seem to play a causal role in the course and the prognosis of AN. A better understanding of these brain changes could lead to more targeted therapies for patients with AN, including astrocyte-directed approaches.

Neuromodulation in eating disorders and obesity: a promising way of treatment?

Neuromodulation can affect the functioning of the central nervous system (CNS), and emotional/eating behavior is an exciting facet of that functioning. Therefore, it would be possible to offer an alternative (or complement) treatment to psychotropic medications and different psychological and nutritional approaches to both eating disorders (EDs) and obesity. Although there are a number of publications in these areas, a systematic review has not been conducted to date. Abstracts, letters, conference reports, dissertations, and reviews were excluded. Clinical trials and controlled human clinical trials were filtered and included in this study. Articles included were based on the population suffering from anorexia nervosa, bulimia nervosa, binge ED, overweight, and obesity. No restrictions were placed on the sample size. Only trials investigating the effect of neuromodulation by means of deep brain stimulation (DBS), transcranial direct current stimulation (tDCS), and transcranial magnetic stimulation (TMS) were included. The following databases were used to conduct the search: MEDLINE/ PubMed, PsycINFO, PsycArticles, and Cochrane (Search Trials, CENTRAL). Study selection was performed following the PRISMA process (PRISMA 2009 Checklist). The total number of participants in all the trials was 562 (DBS, 25; tDCS, 138; TMS, 399; range, 3-90; median, 23.5). As a result, 50% of the studies had samples of between 14 and 38 participants. Neuro-modulation in ED seems to have certain clinical potential, and therefore, this is a promising area for further research. Developments in ED neuromodulation will be linked to neuroimaging to identify potential stimulation targets and possible biomarkers of treatment response. To date, TMS and/or direct current stimulation (DCS) is not the first-line treatment yet, but it could become a preferred option of treatment in the future. Further studies should avoid small sample sizes and the use of different methodologies. Currently, neuromodulation techniques are in the experimental phase, and they are not an evidence-based treatment for ED.

Assessing the marks of change: how psychotherapy alters the brain structure in women with borderline personality disorder

BACKGROUND

There is increasing evidence that psychotherapy can alter the function of the brain of patients with borderline personality disorder (BPD). However, it is not known whether psychotherapy can also modify the brain structure of patients with BPD.

METHODS

We used structural MRI data of female patients with BPD before and after participation in 12 weeks of residential dialectical behavioural therapy (DBT) and compared them to data from female patients with BPD who received treatment as usual (TAU). We applied voxel-based morphometry to study voxel-wise changes in grey matter volume over time.

RESULTS

We included 31 patients in the DBT group and 17 in the TAU group. Patients receiving DBT showed an increase of grey matter volume in the anterior cingulate cortex, inferior frontal gyrus and superior temporal gyrus together with an alteration of grey matter volume in the angular gyrus and supramarginal gyrus compared with patients receiving TAU. Furthermore, therapy response correlated with increase of grey matter volume in the angular gyrus.

LIMITATIONS

Only women were investigated, and groups differed in size, medication (controlled for) and intensity of the treatment condition.

CONCLUSION

We found that DBT increased grey matter volume of brain regions that are critically implicated in emotion regulation and higher-order functions, such as mentalizing. The role of the angular gyrus for treatment response may reside in its cross-modal integrative function. These findings enhance our understanding of psychotherapy mechanisms of change and may foster the development of neurobiologically informed therapeutic interventions.

The Science Behind the Academy for Eating Disorders' Nine Truths About Eating Disorders

OBJECTIVE

In 2015, the Academy for Eating Disorders collaborated with international patient, advocacy, and parent organizations to craft the 'Nine Truths About Eating Disorders'. This document has been translated into over 30 languages and has been distributed globally to replace outdated and erroneous stereotypes about eating disorders with factual information. In this paper, we review the state of the science supporting the 'Nine Truths'.

METHODS

The literature supporting each of the 'Nine Truths' was reviewed, summarized and richly annotated.

RESULTS

Most of the 'Nine Truths' arise from well-established foundations in the scientific literature. Additional evidence is required to further substantiate some of the assertions in the document. Future investigations are needed in all areas to deepen our understanding of eating disorders, their causes and their treatments.

CONCLUSIONS

The 'Nine Truths About Eating Disorders' is a guiding document to accelerate global dissemination of accurate and evidence-informed information about eating disorders. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

Regional decrease in gray matter volume is related to body dissatisfaction in anorexia nervosa

Anorexia nervosa (AN) is a psychiatric disorder, in which the prognosis for some patients is poor. The etiology and effective treatments for AN have not been established. We examined morphometric changes in the brain of AN and clarified how the changes were associated with symptoms and pathophysiology. We enrolled 52 participants: 7 with the restrictive type of AN, 13 with the binge-eating/purging type, 3 with eating disorder not otherwise specified, and 29 healthy controls. Participants underwent T1-weighted MRI. Group differences between patients and controls in gray matter volume (GMV) were analyzed using voxel-based morphometry. Age and body mass index (BMI) were considered covariates. Correlations between regional GMVs and drive for thinness and body dissatisfaction were examined. Patients had decreased GMV in the superior/middle temporal gyrus (STG/MTG), pulvinar, and superior frontal gyrus after correction for age and BMI, and in the STG/MTG, middle frontal gyrus, and cingulate after correction for age. A correlational group difference was detected for body dissatisfaction and GMV in the STG. Our findings suggest that decreased GMV in the STG is related to body dissatisfaction that could come from impaired visuospatial perception, together with GMV decreases in several regions, which may be involved in development of AN.

Treatment of anorexia nervosa: a multimethod investigation translating experimental neuroscience into clinical practice

Background

Anorexia nervosa (AN) is a severe psychiatric condition and evidence on how to best treat it is limited.

Objectives

This programme consists of seven integrated work packages (WPs) and aims to develop and test disseminable and cost-effective treatments to optimise management for people with AN across all stages of illness.

Methods

WP1a used surveys, focus groups and a pre–post trial to develop and evaluate a training programme for school staff on eating disorders (EDs). WP1b used a randomised controlled trial (RCT) [International Standard Randomised Controlled Trial Number (ISRCTN) 42594993] to evaluate a prevention programme for EDs in schools. WP2a evaluated an inpatient treatment for AN using case reports, interviews and a quasi-experimental trial. WP2b used a RCT (ISRCTN67720902) to evaluate two outpatient psychological therapies for AN. WP3 used a RCT (ISRCTN06149665) to evaluate an intervention for carers of inpatients with AN. WP4 used actimetry, self-report and endocrine assessment to examine physical activity (PA) in AN. WP5 conducted a RCT (ISRCTN18274621) of an e-mail-guided relapse prevention programme for inpatients with AN. WP6 analysed cohort data to examine the effects of maternal EDs on fertility and their children’s diet and growth. WP7a examined clinical case notes to explore how access to specialist ED services affects care pathways and user experiences. Finally, WP7b used data from this programme and the British Cohort Study (1970) to identify the costs of services used by people with AN and to estimate annual costs of AN for England.

Results

WP1a: a brief training programme improved knowledge, attitudes and confidence of school staff in managing EDs in school. WP1b: a teacher-delivered intervention was feasible and improved risk factors for EDs in adolescent girls. WP2a: both psychological therapies improved outcomes in outpatients with AN similarly, but patients preferred one of the treatments. WP2b: the inpatient treatment (Cognitive Remediation and Emotional Skills Training) was acceptable with perceived benefits by patients, but showed no benefits compared with treatment as usual (TAU). WP3: compared with TAU, the carer intervention improved a range of patient and carer outcomes, including carer burden and patient ED symptomatology. WP4: drive to exercise is tied to ED pathology and a desire to improve mood in AN patients. PA was not increased in these patients. WP5: compared with TAU, the e-mail-guided relapse prevention programme resulted in higher body mass index and lower distress in patients at 12 months after discharge. WP6: women with an ED had impaired fertility and their children had altered dietary and growth patterns compared with the children of women without an ED. WP7a: direct access to specialist ED services was associated with higher referral rates, lower admission rates, greater consistency of care and user satisfaction. WP7b: the annual costs of AN in England are estimated at between £45M and £230M for 2011.

Conclusions

This programme has produced evidence to inform future intervention development and has developed interventions that can be disseminated to improve outcomes for individuals with AN. Directions for future research include RCTs with longer-term outcomes and sufficient power to examine mediators and moderators of change.

Trial registration

Current Controlled Trials ISRCTN42594993, ISRCTN67720902, ISRCTN06149665 and ISRCTN18274621.

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 5, No. 16. See the NIHR Journals Library website for further project information.

Neural correlates of altered feedback learning in women recovered from anorexia nervosa

Anorexia nervosa (AN) is associated with exaggerated self-control and altered reward-based decision making, but the underlying neural mechanisms are poorly understood. Consistent with the notion of excessive cognitive control, we recently found increased dorsal anterior cingulate cortex (dACC) activation in acutely ill patients (acAN) on lose-shift trials in a probabilistic reversal learning (PRL) task. However, undernutrition may modulate brain function. In attempt to disentangle trait from state factors, the current fMRI study investigated cognitive control in recovered patients (recAN). Thirty-one recAN and 31 healthy controls (HC) completed a PRL task during fMRI. Based on previous findings, we focused on hemodynamic responses during lose-shift behaviour and conducted supplementary functional connectivity analysis. RecAN showed elevated lose-shift behaviour relative to HC. On the neural level, recAN showed normal dACC responses, but increased activation in fronto-parietal control regions. A trend for increased coupling between frontal and parietal regions of interest was also evident in recAN. The current findings in recAN differ from those in our previous study in acAN. While aberrant dACC response to negative feedback may be a correlate of the underweight state in acAN, impaired behavioural adaptation and elevated activation of cognitive control regions in recAN is suggestive of altered neural efficiency.

Interhemispheric functional connectivity in anorexia and bulimia nervosa

The functional interplay between hemispheres is fundamental for behavioral, cognitive, and emotional control. Anorexia nervosa (AN) and bulimia nervosa (BN) have been largely studied with brain magnetic resonance imaging (MRI) in relation to the functional mechanisms of high-level processing, but not in terms of possible inter-hemispheric functional connectivity anomalies. Using resting-state functional MRI (fMRI), voxel-mirrored homotopic connectivity (VMHC) and regional inter-hemispheric spectral coherence (IHSC) were studied in 15 AN and 13 BN patients and 16 healthy controls (HC). Using T1-weighted and diffusion tensor imaging MRI scans, regional VMHC values were correlated with the left-right asymmetry of corresponding homotopic gray matter volumes and with the white matter callosal fractional anisotropy (FA). Compared to HC, AN patients exhibited reduced VMHC in cerebellum, insula, and precuneus, while BN patients showed reduced VMHC in dorso-lateral prefrontal and orbito-frontal cortices. The regional IHSC analysis highlighted that the inter-hemispheric functional connectivity was higher in the 'Slow-5' band in all regions except the insula. No group differences in left-right structural asymmetries and in VMHC vs. callosal FA correlations were significant in the comparisons between cohorts. These anomalies, not explained by structural changes, indicate that AN and BN, at least in their acute phase, are associated with a loss of inter-hemispheric connectivity in regions implicated in self-referential, cognitive control and reward processing. These findings may thus gather novel functional markers to explore aberrant features of these eating disorders.

Altered microstructure of brain white matter in females with anorexia nervosa: a diffusion tensor imaging study

OBJECTIVE

Structural studies have reported anorexia nervosa (AN) patients with abnormal gray matter in several brain regions and dysfunction in some connected neural circuits. However, the role of white matter (WM) in AN patients has rarely been investigated. The present study aimed to assess alterations in WM microstructure of the entire brain in females with AN using a voxel-based method on diffusion tensor imaging (DTI) data.

MATERIALS AND METHODS

The study enrolled 8 female patients with AN and 14 age-matched females as controls (CW). The DTI data was collected from each subject to calculate the fractional anisotropy (FA) maps of the whole brain by the DTI-Studio software. Subsequently, a 2-sample t-test (P<0.05, corrected) was performed to detect the difference in FA maps of AN and CW group, and a Pearson's correlation analyzed the relationship between mean FA value of brain regions and body mass index (BMI).

RESULTS

Compared with CW, AN patients revealed a significant decrease in FA maps in the left superior frontal gyrus, medial frontal gyrus, anterior cingulate cortex, middle frontal gyrus, inferior frontal gyrus, thalamus, and bilateral insula. Moreover, significantly positive correlations were established between the mean FA value of the left inferior frontal gyrus, insula as well as thalamus and BMI in AN patients.

CONCLUSIONS

Our findings supported the presence of WM abnormality in patients with AN. The significant differences of FA maps, in patients with AN, were associated with their aberrant BMI. The results further improved our understanding of the pathophysiological mechanisms underlying AN.

Reduced Resting-State Functional Connectivity in Current and Recovered Restrictive Anorexia Nervosa

Functional connectivity studies based on resting-state functional magnetic resonance imaging (rs-fMRI) have shown alterations in brain networks associated with self-referential processing, cognitive control, and somatosensory processing in anorexia nervosa (AN). This study aimed to further investigate the functional connectivity of resting-state networks (RSNs) in homogenous subsamples of individuals with restrictive AN (current and recovered) and the relationship this has with core eating disorder psychopathology. rs-fMRI scans were obtained from 12 female individuals with restrictive AN, 14 females recovered from restrictive AN, and 16 female healthy controls. Independent components analysis revealed a set of functionally relevant RSNs, previously reported in the literature. Dual regression analysis showed decreased temporal coherence within the lateral visual and auditory RSNs in individuals with current AN and those recovered from AN compared to healthy individuals. This decreased connectivity was also found in regions associated with somatosensory processing, and is consistent with reduced interoceptive awareness and body image perception, characteristic of AN. Widespread gray matter (GM) reductions were also found in both the AN groups, and differences in functional connectivity were no longer significant when GM maps were added as a covariate in the dual regression analysis. This raises the possibility that deficits in somatosensory and interoceptive processing observed in AN may be in part underpinned or exacerbated by GM reductions.

Cortico-Striatal-Thalamic Loop Circuits of the Salience Network: A Central Pathway in Psychiatric Disease and Treatment

The salience network (SN) plays a central role in cognitive control by integrating sensory input to guide attention, attend to motivationally salient stimuli and recruit appropriate functional brain-behavior networks to modulate behavior. Mounting evidence suggests that disturbances in SN function underlie abnormalities in cognitive control and may be a common etiology underlying many psychiatric disorders. Such functional and anatomical abnormalities have been recently apparent in studies and meta-analyses of psychiatric illness using functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM). Of particular importance, abnormal structure and function in major cortical nodes of the SN, the dorsal anterior cingulate cortex (dACC) and anterior insula (AI), have been observed as a common neurobiological substrate across a broad spectrum of psychiatric disorders. In addition to cortical nodes of the SN, the network’s associated subcortical structures, including the dorsal striatum, mediodorsal thalamus and dopaminergic brainstem nuclei, comprise a discrete regulatory loop circuit. The SN’s cortico-striato-thalamo-cortical loop increasingly appears to be central to mechanisms of cognitive control, as well as to a broad spectrum of psychiatric illnesses and their available treatments. Functional imbalances within the SN loop appear to impair cognitive control, and specifically may impair self-regulation of cognition, behavior and emotion, thereby leading to symptoms of psychiatric illness. Furthermore, treating such psychiatric illnesses using invasive or non-invasive brain stimulation techniques appears to modulate SN cortical-subcortical loop integrity, and these effects may be central to the therapeutic mechanisms of brain stimulation treatments in many psychiatric illnesses. Here, we review clinical and experimental evidence for abnormalities in SN cortico-striatal-thalamic loop circuits in major depression, substance use disorders (SUD), anxiety disorders, schizophrenia and eating disorders (ED). We also review emergent therapeutic evidence that novel invasive and non-invasive brain stimulation treatments may exert therapeutic effects by normalizing abnormalities in the SN loop, thereby restoring the capacity for cognitive control. Finally, we consider a series of promising directions for future investigations on the role of SN cortico-striatal-thalamic loop circuits in the pathophysiology and treatment of psychiatric disorders.

Mammillary body volume abnormalities in anorexia nervosa

OBJECTIVE

Several case reports of Wernicke's Encephalopathy in anorexia nervosa (AN) caused by thiamine deficiency have described mammillary body (MB) injury, but systematic studies are lacking. Here we evaluated whether underweight and weight-restored individuals with AN demonstrate evidence of abnormal MB morphology, via retrospective examination of a previously collected data set.

METHOD

Using standard-resolution T1-weighted magnetic resonance imaging at 3 Tesla, we measured MB volume and fornix area in a cross-sectional study of 12 underweight AN, 20 weight-restored AN, and 30 age- and sex-matched healthy comparisons. Because of the small size of these structures, a manual tracing approach was necessary to obtain accurate measurements. A blinded expert rater manually traced MB and fornix structures in each participant.

RESULTS

We observed significantly smaller MB volumes in the underweight AN group. However, the weight-restored AN group exhibited significantly larger MB volumes. The right fornix was smaller in the weight-restored AN group only.

DISCUSSION

These findings suggest the possibility that MB volume and fornix area could represent potential biomarkers of acute weight loss and restoration, respectively. Verification of this finding through prospective studies evaluating MB morphology, cognition, and thiamine levels longitudinally across individual illness trajectories might be warranted. © 2016 Wiley Periodicals, Inc. (Int J Eat Disord 2016; 49:920-929).

Extremes of eating are associated with reduced neural taste discrimination

OBJECTIVE

Eating disorders are severe psychiatric disorders of unknown etiology. Understanding how neuronal function affects food choices could help personalize treatment based on brain function. Here we wanted to determine whether disordered eating behavior is associated with alterations in the primary taste cortex's ability to classify taste stimuli, which could interfere with taste reward processing.

METHOD

One-hundred and six women, 27 healthy comparison (age 26.15 ± 6.95 years), 21 with restricting-type anorexia nervosa (AN; age 23.10 ± 6.14 years), 19 recovered from restricting-type AN (recovered AN; age 26.95 ± 5.31 years), 20 with bulimia nervosa (BN; age 25.15 ± 5.31 years), and 19 with obesity (age 28.16 ± 8.13 years), received sucrose, control solution or no taste stimulation during functional magnetic resonance brain imaging. Multivariate Bayesian pattern analysis (decoding) and cross-validation tested taste classification accuracy (adjusted for comorbidity, medication use, taste perception, interoception, and brain activation volume).

RESULTS

For sucrose versus control solution, classification accuracy differed (F = 2.53, P < 0.041). Post hoc tests indicated higher classification accuracy in healthy comparison compared to women with AN (P < 0.016) or obesity (P < 0.027), and in recovered AN as compared to AN (P < 0.016) or obesity (P < 0.047) groups. Taste stimulation resulted in sparse insula voxel activation across all groups.

DISCUSSION

Reduced classification accuracy across stimuli in women with AN or obesity could indicate low brain encoding discrimination of stimulus quality, which could contribute to altered reward activation and eating drive that is not adjusted to nutritional needs. This deficit appears to normalize with recovery from AN, but adjusting food flavor intensity could aid in the treatment of individuals with AN or obesity. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2016; 49:603-612).

Two cases of food aversion with semantic dementia

Accounts of altered eating behavior in semantic dementia generally emphasize gluttony and abnormal food preferences. Here we describe two female patients with no past history of eating disorders who developed early prominent aversion to food in the context of an otherwise typical semantic dementia syndrome. One patient (aged 57) presented features in line with anorexia nervosa while the second patient (aged 58) presented with a syndrome more suggestive of bulimia nervosa. These cases add to the growing spectrum of apparently dichotomous behavior patterns in the frontotemporal dementias and illustrate a potentially under-recognized cause of eating disorders presenting in later life.

Normal gray matter volumes in women recovered from anorexia nervosa: a voxel-based morphometry study

BACKGROUND

Anorexia nervosa (AN) has consistently been associated with reduced gray (GM) and white matter (WM) brain volumes. It is unclear whether GM alterations are present following recovery from AN, as previous findings are inconsistent. The aim of the present study was to determine if women recovered from AN exhibit reduced global or regional GM volumes.

METHODS

Global GM and WM, as well as regional GM volumes, were investigated in 22 women recovered from AN and 22 age-matched healthy controls using magnetic resonance imaging. Women were considered recovered if they had maintained a body mass index above 18.0 and had not engaged in binge eating, purging, or restrictive eating behaviors during the past year.

RESULTS

There were no significant differences between recovered AN women and healthy controls in terms of GM and WM volumes. There were also no significant differences between restricting and binging-purging AN subtypes. Lowest lifetime weight was positively correlated with regional GM volumes in the precuneus and insula.

CONCLUSIONS

The present study showed that regional GM and global GM and WM volumes were similar for women long-term recovered from AN and age-matched healthy controls. Further research is needed to determine the extent to which illness severity affect regional GM volumes.

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

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