Hippocampal volume and cognitive function in anorexia nervosa

Autobiographical memory following weight gain in adult patients with Anorexia Nervosa: A longitudinal study

BACKGROUND

Patients with anorexia nervosa (AN) show overgeneralization of memory (OGM) when generating autobiographical episodes related to food and body shape. These memories are central for the construction of a coherent self-concept, interpersonal relationships, and problem-solving abilities. The current study aims to investigate changes in autobiographical memory following weight gain.

METHODS

OGM was assessed with an adapted version of the Autobiographical Memory Test including food-, body-, depression-related, and neutral cues. N = 41 female patients with AN (28 restricting-, 13 binge-eating/purging-subtype; mean disease duration: 4.5 years; mean BMI: 14.5 kg/m2) and N = 27 healthy controls (HC) were included at baseline. After inpatient treatment (mean duration: 11 weeks), 24 patients with AN and 24 age-matched HC were reassessed. Group differences were assessed using independent samples t-tests for cross-sectional comparisons and repeated measures ANOVAs for longitudinal data.

RESULTS

At baseline, patients with AN generated significantly fewer specific memories than HC, independent of word category (F(1.66) = 27.167, p < 0.001). During inpatient stay, the average weight gain of patients with AN was 3.1 body mass index points. At follow-up, patients with AN showed a significant improvement in the number of specific memories for both depression-related and neutral cues, but not for food- and body-related cues.

CONCLUSIONS

Generalised OGM (i.e., independent of word category) in patients with AN before weight restoration may be a general incapacity to recall autobiographical memory. After weight gain, the previously well-studied pattern of eating disorder-related OGM emerges. The clinical relevance of the continuing disorder-related OGM in patients with AN after weight gain is discussed.

Behavioural and emotional symptoms of adolescents consulting a specialised eating disorders programme

INTRODUCTION

Eating disorders (EDs) are complex conditions of multifactorial origin. Their main characteristic is excessive concern about body weight and shape, which causes great discomfort and physical problems and leads to a decrease in quality of life and alterations in the patient's functionality social environment. The objective of this study is to describe the emotional and behavioural symptoms of adolescents who consult a specialised ED programme in the city of Bogota.

METHODS

Observational, descriptive, cross-sectional study, for which patients between 11 and 19 years old with an ED diagnosis were recruited.

RESULTS

Forty patients with an ED diagnosis were included, of which 92% were female. The mean age of the patients was 16.6±1.9 years; 57% of patients live in a two-parent home and 30% in a single-parent home; 72% of the sample had excellent academic performance; 50% were moderately ill; 60% received pharmacological management with SSRIs; 65% of patients met clinical criteria for anxiety disorder, 30% for depressive disorder; 22.5% had aggression problems; 17.5% criminal behaviour; 72.5% of the sample met clinical criteria for internalising symptoms and 42.5% for externalising symptoms, the majority being patients with a diagnosis of bulimia nervosa.

CONCLUSIONS

Patients with bulimia nervosa obtained higher scores in the different emotional and behavioural symptoms than those with other eating disorders. This condition is associated with greater psychopathology, which must be examined rigorously at the time of clinical care, seeking to reduce the functional impact that these symptoms generate on the individual.

Activity-based anorexia animal model: a review of the main neurobiological findings

BACKGROUND

The genesis of anorexia nervosa (AN), a severe eating disorder with a pervasive effect on many brain functions such as attention, emotions, reward processing, cognition and motor control, has not yet been understood. Since our current knowledge of the genetic aspects of AN is limited, we are left with a large and diversified number of biological, psychological and environmental risk factors, called into question as potential triggers of this chronic condition with a high relapse rate. One of the most valid and used animal models for AN is the activity-based anorexia (ABA), which recapitulates important features of the human condition. This model is generated from naïve rodents by a self-motivated caloric restriction, where a fixed schedule food delivery induces spontaneous increased physical activity.

AIM

In this review, we sought to provide a summary of the experimental research conducted using the ABA model in the pursuit of potential neurobiological mechanism(s) underlying AN.

METHOD

The experimental work presented here includes evidence for neuroanatomical and neurophysiological changes in several brain regions as well as for the dysregulation of specific neurochemical synaptic and neurohormonal pathways.

RESULTS

The most likely hypothesis for the mechanism behind the development of the ABA phenotype relates to an imbalance of the neural circuitry that mediates reward processing. Evidence collected here suggests that ABA animals show a large set of alterations, involving regions whose functions extend way beyond the control of reward mechanisms and eating habits. Hence, we cannot exclude a primary role of these alterations from a mechanistic theory of ABA induction.

CONCLUSIONS

These findings are not sufficient to solve such a major enigma in neuroscience, still they could be used to design ad hoc further experimental investigation. The prospect is that, since treatment of AN is still challenging, the ABA model could be more effectively used to shed light on the complex AN neurobiological framework, thus supporting the future development of therapeutic strategies but also the identification of biomarkers and diagnostic tools. Anorexia Nervosa (AN) is a severe eating disorder with a dramatic effect on many functions of our brain, such as attention, emotions, cognition and motion control. Since our current knowledge of the genetic aspects behind the development of AN is still limited, many biological, psychological and environmental factors must be taken into account as potential triggers of this condition. One of the most valid animal models for studying AN is the activity-based anorexia (ABA). In this model, rodents spontaneously limit food intake and start performing increased physical activity on a running wheel, a result of the imposition of a fixed time schedule for food delivery. In this review, we provide a detailed summary of the experimental research conducted using the ABA model, which includes extended evidence for changes in the anatomy and function of the brain of ABA rodents. The hope is that such integrated view will support the design of future experiments that will shed light on the complex brain mechanisms behind AN. Such advanced knowledge is crucial to find new, effective strategies for both the early diagnosis of AN and for its treatment.

The Neuropsychological Profile of Severe and Enduring Anorexia Nervosa: A Systematic Review

Characteristics of Severe and Enduring Anorexia Nervosa (SE-AN) are being investigated to differentiate the patients experiencing SE-AN from those at earlier stages of the AN disease. The current systematic review was the first step in exploring neuropsychological functioning as a potentially identifying characteristic for long-term presentations. With a subgroup of AN patients reflecting a unique neuropsychological profile that is proportionate to the quantity of patients that go on to develop SE-AN, it was the aim of this review to assess neuropsychological functioning in the later stage of the disease. In accordance with PRISMA guidelines, a literature search was conducted using four electronic databases (PsycINFO, MEDLINE, Web of Science, and Scopus) for neuropsychological research on AN participants with a seven or more year illness duration. Datasets that met inclusion criteria were screened for SE-AN participants (N = 166) and neuropsychological data extracted together with potentially confounding variables and information required to conduct a quality assessment. In research investigating decision-making, participants with a SE-AN presentation demonstrated significantly lower functioning compared to healthy controls. There was conflicting evidence for differences in intellectual functioning and set-shifting abilities with no variability indicated in central coherence, memory, attention, reasoning, or processing speed. If findings from this preliminary analysis are confirmed through empirical research, implications include earlier identification of SE-AN patients and more effective treatment development.

Structural and functional brain alterations in anorexia nervosa:A multimodal meta-analysis of neuroimaging studies

Anorexia nervosa (AN) is a complex psychiatric disorder with poorly understood etiology. Numerous voxel‐based morphometry (VBM) and resting‐state functional imaging studies have provided strong evidence of abnormal brain structure and intrinsic and functional activities in AN, but with inconsistent conclusions. Herein, a whole‐brain meta‐analysis was conducted on VBM (660 patients with AN, and 740 controls) and resting‐state functional imaging (425 patients with AN, and 461 controls) studies that measured differences in the gray matter volume (GMV) and intrinsic functional activity between patients with AN and healthy controls (HCs). Overall, patients with AN displayed decreased GMV in the bilateral median cingulate cortex (extending to the bilateral anterior and posterior cingulate cortex), and left middle occipital gyrus (extending to the left inferior parietal lobe). In resting‐state functional imaging studies, patients with AN displayed decreased resting‐state functional activity in the bilateral anterior cingulate cortex and bilateral median cingulate cortex, and increased resting‐state functional activity in the right parahippocampal gyrus. This multimodal meta‐analysis identified reductions of gray matter and functional activity in the anterior and median cingulate in patients with AN, which contributes to further understanding of the pathophysiology of AN.

Post-traumatic stress disorder may set the neurobiological stage for eating disorders: A focus on glutamatergic dysfunction

Post-traumatic stress disorder (PTSD) is a trauma and stress-related disorder which has been shown to be highly comorbid with, and commonly a precedent of, the eating disorders anorexia nervosa, bulimia nervosa, and binge eating disorder. The objective of this review is to discuss a potential overlapping neurobiological mechanism for this comorbidity. Alterations in glutamatergic neurotransmission have been observed in all four of the aforementioned disorders. Excessive excitation via glutamate contributes to excitotoxicity, and over-activation of the hypothalamic-pituitary-adrenal axis, both of which have implications for the deterioration of various brain structures. Prominent structures impacted include the hippocampus, hypothalamus, and prefrontal cortex, all of which are integral to the regulation of stress and eating. The current review suggests that altered glutamate function by trauma or extreme stress may facilitate PTSD and subsequent eating disorder onset, and that glutamatergic modulation may be a key treatment for individuals suffering from these conditions. This overlapping mechanism may help inform future research on individuals with comorbid PTSD and eating disorders, and it could also help inform ways to potentially prevent the onset of these conditions.

A Review of Antiviral and Antioxidant Activity of Bioactive Metabolite of Macroalgae within an Optimized Extraction Method

Non-conventional extraction of bioactive metabolites could provide sustainable alternative techniques to preserve the potency of antioxidants and antiviral compounds extracted from macro-algae. In this paper, we first reviewed the antioxidant and antiviral potential of the active metabolites that exist in the three known macro-algae classes; Phaeophyceae, Rhodophyceae, and Chlorophyceae, and a comparison between their activities is discussed. Secondly, a review of conventional and non-conventional extraction methods is undertaken. The review then focused on identifying the optimal extraction method of sulphated polysaccharide from macro-algae that exhibits both antiviral and antioxidant activity. The review finds that species belonging to the Phaeophyceae and Rhodophceae classes are primarily potent against herpes simplex virus, followed by human immunodeficiency virus and influenza virus. At the same time, species belonging to Chlorophyceae class are recorded by most of the scholars to have antiviral activity against herpes simplex virus 1. Additionally, all three macro-algae classes exhibit antioxidant activity, the potency of which is a factor of the molecular structure of the bioactive metabolite as well as the extraction method applied.

Behavioural and Emotional Symptoms of Adolescents Consulting a Specialised Eating Disorders Programme

INTRODUCTION

Eating disorders (EDs) are complex conditions of multifactorial origin. Their main characteristic is excessive concern about body weight and shape, which causes great discomfort and physical problems and leads to a decrease in quality of life and alterations in the patient's functionality social environment. The objective of this study is to describe the emotional and behavioural symptoms of adolescents who consult a specialised ED programme in the city of Bogota.

METHODS

Observational, descriptive, cross-sectional study, for which patients between 11 and 19 years old with an ED diagnosis were recruited.

RESULTS

Forty patients with an ED diagnosis were included, of which 92% were female. The mean age of the patients was 16.6±1.9 years; 57% of patients live in a two-parent home and 30% in a single-parent home; 72% of the sample had excellent academic performance; 50% were moderately ill; 60% received pharmacological management with SSRIs; 65% of patients met clinical criteria for anxiety disorder, 30% for depressive disorder; 22.5% had aggression problems; 17.5% criminal behaviour; 72.5% of the sample met clinical criteria for internalising symptoms and 42.5% for externalising symptoms, the majority being patients with a diagnosis of bulimia nervosa.

CONCLUSIONS

Patients with bulimia nervosa obtained higher scores in the different emotional and behavioural symptoms than those with other eating disorders. This condition is associated with greater psychopathology, which must be examined rigorously at the time of clinical care, seeking to reduce the functional impact that these symptoms generate on the individual.

Hippocampal volume, function, and related molecular activity in anorexia nervosa: A scoping review

INTRODUCTION

Anorexia nervosa (AN) is a serious and persistent eating disorder, characterized by severe dietary restriction and weight loss, with a third of patients developing a  severe-enduring form. The factors contributing to this progression are poorly understood, although there is evidence for impairments in neural structures such as the hippocampus, an area particularly affected by malnutrition and chronic stress.

AREAS COVERED

This study aimed to map the evidence for alterations in hippocampal volume, function, and related molecular activity in anorexia nervosa. PubMed, PsycINFO, and Web of Science were searched for studies related to hippocampal function and integrity using a range of methodologies, such as neuropsychological paradigms, structural and functional magnetic resonance imaging, and analysis of blood components.

EXPERT OPINION

Thirty-nine studies were included in this review. The majority were neuroimaging studies, which found hippocampus-specific volumetric and functional impairments. Neuropsychological studies showed evidence for a specific memory and learning impairments. There was some evidence for molecular abnormalities (e.g. cortisol), although these were few studies. Taken together, our review suggests that the hippocampus might be a particular region of interest when considering neurobiological approaches to understanding AN. These findings warrant further investigation and may lead to novel treatment approaches.

Hippocampal volumes in anorexia nervosa at different stages of the disorder

INTRODUCTION

Hippocampus is involved in a range of cognitive and behavioural processes, and its volume has been found to be reduced in different psychiatric disorders. The present study aims at exploring hippocampal volumes in anorexia nervosa (AN) at different stages of the disorder (a few months after onset, more than 1 year after onset and after recovery).

METHODS

Two samples were included in the present study. The first was composed of 58 patients (38 with present AN, 20 full recovered from AN) and 38 age-matched healthy women (HW); the second, recruited at a different site, included 20 patients with AN and 16 HW. Hippocampal volume has been estimated using an automated segmentation algorithm. Age, site of scanning and total intracranial volumes were used as covariates in the statistical analyses.

RESULTS

AN patients showed a reduced hippocampal volume in comparison to HW, with no substantial differences between patients with recent onset and those with a longer duration of illness. Among patients, hippocampal volumes correlated with body mass index, anxiety and drive for thinness.

DISCUSSION

Our findings suggest an early role of malnutrition in the morphologic alterations of the hippocampus in AN and a possible role of this brain structure in mediating specific psychopathological traits.

Maternal Separation in ABA Rats Promotes Cell Proliferation in the Dentate Gyrus of the Hippocampus

Anorexia nervosa (AN) is a serious eating disorder characterized by self-starvation and excessive weight loss. Several studies support the idea that life stressors during the postnatal period could play a pivotal role in the pathogenesis of AN, underlying the multifactorial etiology of this disease. The activity-based anorexia (ABA) animal model mimics core features of the mental disorder, including severe food restriction, weight loss, and hyperactivity. Previous results obtained in our lab showed that maternal separation (MS) induces behavioral changes in anorexic-like ABA rats in a sexually dimorphic way: in females, the MS promoted hyperactivity and a less anxious-like phenotype in ABA animals; in males, instead, the MS attenuated the anxiolytic effect of the ABA protocol. These results led us to investigate the effect of the MS on brain areas involved in the control of the anxiety-like behavior. We focused our attention on the adult hippocampal neurogenesis, a process involved in the response to environmental stimuli and stressful condition. We analyzed the volume of the whole hippocampus and the proliferation rate in the dentate gyrus (DG) by quantifying Ki67-cells density and characterizing neuronal phenotype (DCX) and glial cells (GFAP) with double-fluorescence technique. The results obtained showed that only in maternally separated anorexic rats there is an increase of proliferation in DG, underlying the presence of a synergic effect of MS and ABA that boost the proliferation of new neurons and glia progenitors in a more evident way in females in comparison to males.

Cognitive Interpersonal Model for Anorexia Nervosa Revisited: The Perpetuating Factors that Contribute to the Development of the Severe and Enduring Illness

The cognitive interpersonal model was outlined initially in 2006 in a paper describing the valued and visible aspects of anorexia nervosa (Schmidt and Treasure, 2006). In 2013, we summarised many of the cognitive and emotional traits underpinning the model (Treasure and Schmidt, 2013). In this paper, we describe in more detail the perpetuating aspects of the model, which include the inter- and intrapersonal related consequences of isolation, depression, and chronic stress that accumulate in the severe and enduring stage of the illness. Since we developed the model, we have been using it to frame research and development at the Maudsley. We have developed and tested interventions for both patients and close others, refining the model through iterative cycles of model/intervention development in line with the Medical Research Council (MRC) framework for complex interventions. For example, we have defined the consequences of living with the illness on close others (including medical professionals) and characterised the intense emotional reactions and behaviours that follow. For the individual with an eating disorder, these counter-reactions can allow the eating disorder to become entrenched. In addition, the consequent chronic stress from starvation and social pain set in motion processes such as depression, neuroprogression, and neuroadaptation. Thus, anorexia nervosa develops a life of its own that is resistant to treatment. In this paper, we describe the underpinnings of the model and how this can be targeted into treatment.

Plasma neurofilament light chain concentration is increased in anorexia nervosa

Anorexia nervosa (AN) is a severe psychiatric disorder with high mortality and, to a large extent, unknown pathophysiology. Structural brain differences, such as global or focal reductions in grey or white matter volumes, as well as enlargement of the sulci and the ventricles, have repeatedly been observed in individuals with AN. However, many of the documented aberrances normalize with weight recovery, even though some studies show enduring changes. To further explore whether AN is associated with neuronal damage, we analysed the levels of neurofilament light chain (NfL), a marker reflecting ongoing neuronal injury, in plasma samples from females with AN, females recovered from AN (AN-REC) and normal-weight age-matched female controls (CTRLS). We detected significantly increased plasma levels of NfL in AN vs CTRLS (median_AN = 15.6 pg/ml, IQR_AN = 12.1-21.3, median_CTRL = 9.3 pg/ml, IQR_CTRL = 6.4-12.9, and p < 0.0001), AN vs AN-REC (median_AN-REC = 11.1 pg/ml, IQR_AN-REC = 8.6-15.5, and p < 0.0001), and AN-REC vs CTRLS (p = 0.004). The plasma levels of NfL are negatively associated with BMI overall samples (β (±se) = -0.62 ± 0.087 and p = 6.9‧10^-12). This indicates that AN is associated with neuronal damage that partially normalizes with weight recovery. Further studies are needed to determine which brain areas are affected, and potential long-term sequelae.

Anorexia increases microglial density and cytokine expression in the hippocampus of young female rats

Anorexia by osmotic dehydration is an adaptive response to hypernatremia and hyperosmolaemia induced by ingestion of a hypertonic solution. Dehydration-induced anorexia (DIA) reproduces weight loss and avoidance of food, despite its availability. By using this model, we previously showed increased reactive astrocyte density in the rat dorsal hippocampus, suggesting a pro-inflammatory environment where microglia may play an important role. However, whether such anorexic condition increases a pro-inflammatory response is unknown. The aim of this study was to test if DIA increases microglial density in the dorsal hippocampus, as well as the expression of pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and interleukin 1 beta (IL-1β) in the hippocampus of young female rats. Our results showed that DIA significantly increased microglial density in CA2-CA3 and dentate gyrus (DG) but not in CA1. However, forced food restriction (FFR) only increased microglial density in the DG. Accordingly, the activated/resting microglia ratio was significantly increased in CA2-CA3 and DG, in DIA and FFR groups. Finally, western blot analysis showed increased expression of IBA1, TNF-α, IL-6 and IL-1β in the hippocampus of both experimental groups. We conclude that anorexia triggers increased reactive microglial density and expression of TNF-α, IL-6 and IL-1β; this environment may result in hippocampal neuroinflammation.

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.

Hippocampal subfields in adolescent anorexia nervosa

Patients with anorexia nervosa (AN) exhibit volume reduction in cerebral gray matter (GM), and several studies report reduced hippocampus volume. The hippocampal subfields (HS) are functionally and structurally distinct, and appear to respond differently to neuropathology. The aim of this study was to investigate HS volumes in adolescent females with restrictive AN compared to a healthy age-matched control group (HC). The FreeSurfer v6.0 package was used to extract brain volumes, and segment HS in 58 female adolescents (AN = 30, HC = 28). We investigated group differences in GM, white matter (WM), whole hippocampus and 12 HS volumes. AN patients had significantly lower total GM and total hippocampal volume. No group difference was found in WM. Volume reduction was found in 11 of the 12 HS, and most results remained significant when adjusting for global brain volume reduction. Investigations of clinical covariates revealed statistically significant relationships between the whole hippocampus, several HS and scores on depression and anxiety scales in AN. Results from this study show that young AN patients exhibit reduced volume in most subfields of the hippocampus, and that this reduction may be more extensive than the observed global cerebral volume loss.

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.

Inflammatory Markers in Anorexia Nervosa: An Exploratory Study

Inflammation has been suggested to play a pathophysiological role in anorexia nervosa (AN). In this exploratory cross-sectional study, we measured serum concentrations of 40 inflammatory markers (including cytokines, chemokines, and adhesion molecules) and brain-derived neurotrophic factor (BDNF) in people with AN (n = 27) and healthy controls (HCs) (n = 13). Many of these inflammatory markers had not been previously quantified in people with AN. Eating disorder (ED) and general psychopathology symptoms were assessed. Body mass index (BMI) and body composition data were obtained. Interleukin (IL)-6, IL-15, and vascular cell adhesion molecule (VCAM)-1 concentrations were significantly elevated and concentrations of BDNF, tumor necrosis factor (TNF)-β, and vascular endothelial growth factor (VEGF)-A were significantly lower in AN participants compared to HCs. Age, BMI, and percentage body fat mass were identified as potential confounding variables for several of these inflammatory markers. Of particular interest is that most of the quantified markers were unchanged in people with AN, despite them being severely underweight with evident body fat loss, and having clinically significant ED symptoms and severe depression and anxiety symptoms. Future research should examine the replicability of our findings and consider the effect of additional potential confounding variables, such as smoking and physical activity, on the relationship between AN and inflammation.

Recovery of cortical volume and thickness after remission from acute anorexia nervosa

OBJECTIVE

Reduced grey (GM) and white matter (WM) volumes and increased cerebrospinal fluid (CSF) have been frequently reported in anorexia nervosa (AN), but studies focusing on cortical thickness (CT) are scarce and findings inconsistent. We conducted the first study in AN that analyzed both parameters in the same study to gain novel and comprehensive insight.

METHOD

Voxel-based morphometry (VBM) analysis was performed on T1-weighted magnetic resonance images from 34 predominantly adult women with acute AN, 24 REC participants, and 41 healthy controls (HC). Global brain segment volumes (GM, WM, and CSF), regional GM volume, and cortical thickness measures were obtained from the same study sample. We further focused on recovery by including a REC group.

RESULTS

The GM and WM volumes were decreased, and correspondingly, the CSF volume increased in the AN in comparison to the HC and REC groups. No significant volume differences between the REC and HC groups could be observed. AN patients showed reduced regional GM volumes in the right hippocampus and the left middle and right inferior frontal gyrus. Cortical thinning occurred in the AN group, which was particularly robust in fronto-parietal areas. The REC and HC groups failed to show any regional GM or cortical thickness differences.

DISCUSSION

AN is accompanied by severe loss of brain volume and cortical thickness as assessed by complementary investigation tools. However, these changes seem to be largely reversible, which should be encouraging for therapists and patients. The underlying neurobiological mechanisms remain unclear and should be assessed in further studies.

Subcortical volume and cortical surface architecture in women with acute and remitted anorexia nervosa: An exploratory neuroimaging study

BACKGROUND

Anorexia nervosa (AN) is a highly heritable psychiatric disorder characterized by starvation and emaciation and associated with changes in brain structure. The precise nature of these changes remains unclear, as does their developmental time course and capacity for reversal with weight-restoration. In this comprehensive neuroimaging study, we sought to characterize these changes by measuring subcortical volume and cortical surface architecture in women with acute and remitted AN.

METHODS

Structural magnetic resonance imaging data was acquired from underweight women with a current diagnosis of AN (acAN: n = 23), weight-recovered women with a past diagnosis of AN (recAN: n = 24), and female controls (HC: n = 24). Subcortical segmentation and cortical surface reconstruction were performed with FreeSurfer 6.0.0, and group differences in regional volume and vertex-wise, cortex-wide thickness, surface area, and local gyrification index (LGI), a measure of folding, were tested with separate univariate analyses of covariance.

RESULTS

Mean hippocampal and thalamic volumes were significantly reduced in acAN participants, as was mean cortical thickness in four frontal and temporal clusters. Mean LGI was significantly reduced in acAN and recAN participants in five frontal and parietal clusters. No significant group differences in cortical surface area were detected.

CONCLUSIONS

Reductions in subcortical volume, cortical thickness, and right postcentral LGI were unique to women with acute AN, indicating state-dependence and pointing towards cellular remodeling and sulcal widening as consequences of disease manifestation. Reductions in bilateral frontal LGI were observed in women with acute and remitted AN, suggesting a role of atypical neurodevelopment in disease vulnerability.

A focus on reward in anorexia nervosa through the lens of the activity-based anorexia rodent model

Patients suffering anorexia nervosa (AN) become anhedonic, unable or unwilling to derive normal pleasures and tend to avoid rewarding outcomes, most profoundly in food intake. The activity-based anorexia model recapitulates many of the pathophysiological and behavioural hallmarks of the human condition, including a reduction in food intake, excessive exercise, dramatic weight loss, loss of reproductive cycles, hypothermia and anhedonia, and therefore it allows investigation into the underlying neurobiology of anorexia nervosa. The use of this model has directed attention to disruptions in central reward neurocircuitry, which may contribute to disease susceptibility. The purpose of this review is to demonstrate the utility of this unique model to provide insight into the mechanisms of reward relevant to feeding and weight loss, which may ultimately help to unravel the neurobiology of anorexia nervosa and, in a broader sense, the foundation of reward-based feeding.

Decreased feedback learning in anorexia nervosa persists after weight restoration

OBJECTIVE

Anorexia Nervosa (AN) is a serious disorder, with a mortality rate the highest of any psychiatric illness. It is notoriously challenging to treat and mechanisms of illness are not well understood. Reward system abnormalities have been proposed across theoretical models of the persistence of AN. Feedback learning is an important component of how reward systems shape behavior and we hypothesized that individuals with AN would show poorer learning from feedback.

METHODS

We administered the acquired equivalence task to measure both learning from incremental feedback and generalization of that learning to novel stimuli. Participants were individuals with AN (n = 36) before and after intensive weight restoration treatment and healthy comparison participants (HC, n = 26) tested twice. Performance was assessed as accuracy during the Learning and Test phases, for both trained and novel stimuli. The relationship between task performance and eating disorder severity at baseline was also assessed.

RESULTS

Both before and after treatment, individuals with AN showed reduced learning from feedback in the Learning phase (F_3,180  = 2.75, p = .048) and lower accuracy during the Test phase (F_1,60  = 4.29, p = .043), as compared with HC. Individuals with AN did not differ from HC in accuracy for novel stimuli (F_1,60  = 1.04, p = .312), indicating no deficit in generalization. Decreased acquisition of feedback learning was associated with longer illness duration and with greater eating disorder symptom severity at baseline.

CONCLUSIONS

Individuals with AN show reduced learning from feedback or reinforcement, which may contribute to difficulties in changing maladaptive behaviors.

Meaningful Memory in Acute Anorexia Nervosa Patients-Comparing Recall, Learning, and Recognition of Semantically Related and Semantically Unrelated Word Stimuli

OBJECTIVE

It is unclear whether observed memory impairment in anorexia nervosa (AN) depends on the semantic structure (categorized words) of material to be encoded. We aimed to investigate the processing of semantically related information in AN.

METHOD

Memory performance was assessed in a recall, learning, and recognition test in 27 adult women with AN (19 restricting, 8 binge-eating/purging subtype; average disease duration: 9.32 years) and 30 healthy controls using an extended version of the Rey Auditory Verbal Learning Test, applying semantically related and unrelated word stimuli.

RESULTS

Short-term memory (immediate recall, learning), regardless of semantics of the words, was significantly worse in AN patients, whereas long-term memory (delayed recall, recognition) did not differ between AN patients and controls.

DISCUSSION

Semantics of stimuli do not have a better effect on memory recall in AN compared to CO. Impaired short-term versus long-term memory is discussed in relation to dysfunctional working memory in AN. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

Brain volumes and regional cortical thickness in young females with anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is a severe mental illness, with an unknown etiology. Magnetic resonance imaging studies show reduced brain volumes and cortical thickness in patients compared to healthy controls. However, findings are inconsistent, especially concerning the anatomical location and extent of the differences. The purpose of this study was to estimate and compare brain volumes and regional cortical thickness in young females with AN and healthy controls.

METHODS

Magnetic resonance imaging data was acquired from young females with anorexia nervosa (n = 23) and healthy controls (n = 28). Two different scanner sites were used. BMI varied from 13.5 to 20.7 within the patient group, and 11 patients had a BMI > 17.5. FreeSurfer was used to estimate brain volumes and regional cortical thickness.

RESULTS

There were no differences between groups in total cerebral cortex volume, white matter volume, or lateral ventricle volume. There were also no volume differences in subcortical grey matter structures. However the results showed reduced cortical thickness bilaterally in the superior parietal gyrus, and in the right inferior parietal and superior frontal gyri.

CONCLUSIONS

The functional significance of the findings is undetermined as the majority of the included patients was already partially weight-restored. We discuss whether these regions could be related to predisposing factors of the illness, or whether they are regions that are more vulnerable to starvation, malnutrition or associated processes in AN.

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).

Anorexia Reduces GFAP+ Cell Density in the Rat Hippocampus

Anorexia nervosa is an eating disorder observed primarily in young women. The neurobiology of the disorder is unknown but recently magnetic resonance imaging showed a volume reduction of the hippocampus in anorexic patients. Dehydration-induced anorexia (DIA) is a murine model that mimics core features of this disorder, including severe weight loss due to voluntary reduction in food intake. The energy supply to the brain is mediated by astrocytes, but whether their density is compromised by anorexia is unknown. Thus, the aim of this study was to estimate GFAP+ cell density in the main regions of the hippocampus (CA1, CA2, CA3, and dentate gyrus) in the DIA model. Our results showed that GFAP+ cell density was significantly reduced (~20%) in all regions of the hippocampus, except in CA1. Interestingly, DIA significantly reduced the GFAP+ cells/nuclei ratio in CA2 (−23%) and dentate gyrus (−48%). The reduction of GFAP+ cell density was in agreement with a lower expression of GFAP protein. Additionally, anorexia increased the expression of the intermediate filaments vimentin and nestin. Accordingly, anorexia increased the number of reactive astrocytes in CA2 and dentate gyrus more than twofold. We conclude that anorexia reduces the hippocampal GFAP+ cell density and increases vimentin and nestin expression.

New Insights in Anorexia Nervosa

Anorexia nervosa (AN) is classically defined as a condition in which an abnormally low body weight is associated with an intense fear of gaining weight and distorted cognitions regarding weight, shape, and drive for thinness. This article reviews recent evidences from physiology, genetics, epigenetics, and brain imaging which allow to consider AN as an abnormality of reward pathways or an attempt to preserve mental homeostasis. Special emphasis is put on ghrelino-resistance and the importance of orexigenic peptides of the lateral hypothalamus, the gut microbiota and a dysimmune disorder of neuropeptide signaling. Physiological processes, secondary to underlying, and premorbid vulnerability factors-the "pondero-nutritional-feeding basements"- are also discussed.

A debate on working memory and cognitive control: can we learn about the treatment of substance use disorders from the neural correlates of anorexia nervosa?

BACKGROUND

Anorexia Nervosa (AN) is a debilitating, sometimes fatal eating disorder (ED) whereby restraint of appetite and emotion is concomitant with an inflexible, attention-to-detail perfectionist cognitive style and obsessive-compulsive behaviour. Intriguingly, people with AN are less likely to engage in substance use, whereas those who suffer from an ED with a bingeing component are more vulnerable to substance use disorder (SUD).

DISCUSSION

This insight into a beneficial consequence of appetite control in those with AN, which is shrouded by the many other unhealthy, excessive and deficit symptoms, may provide some clues as to how the brain could be trained to exert better, sustained control over appetitive and impulsive processes. Structural and functional brain imaging studies implicate the executive control network (ECN) and the salience network (SN) in the neuropathology of AN and SUD. Additionally, excessive employment of working memory (WM), alongside more prominent cognitive deficits may be utilised to cope with the experience of negative emotions and may account for aberrant brain function. WM enables mental rehearsal of cognitive strategies while regulating, restricting or avoiding neural responses associated with the SN. Therefore, high versus low WM capacity may be one of the factors that unites common cognitive and behavioural symptoms in those suffering from AN and SUD respectively. Furthermore, emerging evidence suggests that by evoking neural plasticity in the ECN and SN with WM training, improvements in neurocognitive function and cognitive control can be achieved. Thus, considering the neurocognitive processes of excessive appetite control and how it links to WM in AN may aid the application of adjunctive treatment for SUD.

Structural hippocampal alterations, perceived stress, and coping deficiencies in patients with anorexia nervosa

OBJECTIVE

Anorexia nervosa (AN) is a severe mental illness that mainly affects young females. Studies have found a reduction of the hippocampus-amygdala formation in people with AN, a brain region that is especially vulnerable to stress. In addition, patients with AN were found to perceive higher stress levels and to have more coping deficiencies than healthy controls. No prior study has considered a connection between stress, coping, and the hippocampal volume in AN. Therefore, the purpose of our study was to analyze the volume of hippocampal substructures, and its relation to stress and coping.

METHOD

We tested 21 females currently affected by AN and 21 age-matched normal controls (NC). Demographic and behavioral data were assessed. A magnetic resonance (MR) scanner was used to collect data reflecting volume of cortical structures. We performed comparisons between groups and calculated correlations between the hippocampal volume and coping strategies or stress.

RESULTS

The results showed a significant reduction of the hippocampal fimbria and a significant enlargement of the hippocampal fissure in patients with AN compared to the NC. In addition, patients with AN were found to report higher stress levels and to have more coping deficiencies than healthy controls. The hippocampal volume showed a trend-level association with stress in patients with AN.

DISCUSSION

In sum, our study provides the first-available evidence that perceived stress in patients with AN could be related to hippocampal volume. Our results may contribute to a better understanding of the pathophysiology of AN and, therefore, help to improve the treatment.

Neural correlates of eating disorders: translational potential

Eating disorders are complex and serious psychiatric illnesses whose etiology includes psychological, biological, and social factors. Treatment of eating disorders is challenging as there are few evidence-based treatments and limited understanding of the mechanisms that result in sustained recovery. In the last 20 years, we have begun to identify neural pathways that are altered in eating disorders. Consideration of how these pathways may contribute to an eating disorder can provide an understanding of expected responses to treatments. Eating disorder behaviors include restrictive eating, compulsive overeating, and purging behaviors after eating. Eating disorders are associated with changes in many neural systems. In this targeted review, we focus on three cognitive processes associated with neurocircuitry differences in subjects with eating disorders such as reward, decision-making, and social behavior. We briefly examine how each of these systems function in healthy people, using Neurosynth meta-analysis to identify key regions commonly implicated in these circuits. We review the evidence for disruptions of these regions and systems in eating disorders. Finally, we describe psychiatric and psychological treatments that are likely to function by impacting these regions.

Advances from neuroimaging studies in eating disorders

Over the past decade, brain imaging has helped to better define eating disorder-related brain circuitry. Brain research on gray matter (GM) and white matter (WM) volumes had been inconsistent, possibly due to the effects of acute starvation, exercise, medication, and comorbidity, but newer studies have controlled for such effects. Those studies suggest larger left medial orbitofrontal gyrus rectus volume in ill adult and adolescent anorexia nervosa after recovery from anorexia nervosa, and in adult bulimia nervosa. The orbitofrontal cortex is important in terminating food intake, and altered function could contribute to self-starvation. The right insula, which processes taste but also interoception, was enlarged in ill adult and adolescent anorexia nervosa, as well as adults recovered from the illness. The fixed perception of being fat in anorexia nervosa could be related to altered insula function. A few studies investigated WM integrity, with the most consistent finding of reduced fornix integrity in anorexia and bulimia nervosa-a limbic pathway that is important in emotion but also food intake regulation. Functional brain imaging using basic sweet taste stimuli in eating disorders during the ill state or after recovery implicated repeatedly reward pathways, including insula and striatum. Brain imaging that targeted dopamine-related brain activity using taste-reward conditioning tasks suggested that this circuitry is hypersensitive in anorexia nervosa, but hyporesponsive in bulimia nervosa and obesity. Those results are in line with basic research and suggest adaptive reward system changes in the human brain in response to extremes of food intake-changes that could interfere with normalization of eating behavior.

Brain structure alterations associated with weight changes in young females with anorexia nervosa: a case series

Structural brain changes associated with starvation and clinical measurements were explored in four females with anorexia nervosa with different clinical course, at baseline and 1-year follow-up, after receiving intensive inpatient treatment at a specialized eating disorder unit. Global volume alterations were associated with weight changes. Regional volume alterations were also associated with weight changes, with the largest changes occurring in the nucleus accumbens, amygdala, pallidum, and putamen. Largest changes in cortical thickness occurred in the frontal and temporal lobes. The results are preliminary; however, they show that fluctuations in weight are associated with brain volume alterations, especially gray matter. We suggest that these parts of the brain are vulnerable to starvation and malnutrition, and could be a part of the pathophysiology of AN.

Cognitive profile of children and adolescents with anorexia nervosa

Objective

Few studies of cognitive functioning in children and adolescents with anorexia nervosa (AN) have been conducted. The aim of this study was to examine the neurocognitive and intelligence profile of this clinical group.

Method

The study was a matched case–control (N = 188), multi-centre study including children and adolescents with AN (N = 94) and healthy control participants (N = 94).

Results

The results suggest that Full Scale Intelligence Quotient (Wechsler Intelligence Scale for Children-III/Wechsler Adult Intelligence Scale-III) in this patient group is close to the normal population mean of 100. Individuals with AN exhibited significantly worse performance in nonverbal intelligence functions (i.e. Wechsler Intelligence Scale for Children-III/Wechsler Adult Intelligence Scale-III, Perceptual Organization Index) and in verbal memory (Test of Memory and Learning—Second Edition, Memory for Stories) and motor speed (Cambridge Neuropsychological Test Automated Battery, Simple and Choice Reaction Time) compared with healthy control participants. No significant difference in set-shifting ability (Cambridge Neuropsychological Test Automated Battery, Intra-Extra Dimensional Set Shift and Trail Making Test B) was found.

Conclusions

Inefficiency in nonverbal intelligence functions and in specific cognitive functions was found in this study of children and adolescents with AN. © 2014 The Authors. European Eating Disorders Review published by John Wiley & Sons, Ltd.

Disruption of brain white matter microstructure in women with anorexia nervosa

BACKGROUND

The etiology of anorexia nervosa is still unknown. Multiple and distributed brain regions have been implicated in its pathophysiology, implying a dysfunction of connected neural circuits. Despite these findings, the role of white matter in anorexia nervosa has been rarely assessed. In this study, we used diffusion tensor imaging (DTI) to characterize alterations of white matter microstructure in a clinically homogeneous sample of patients with anorexia nervosa.

METHODS

Women with anorexia nervosa (restricting subtype) and healthy controls underwent brain DTI. We used tract-based spatial statistics to compare fractional anisotropy (FA) and mean diffusivity (MD) maps between the groups. Furthermore, axial (AD) and radial diffusivity (RD) measures were extracted from regions showing group differences in either FA or MD.

RESULTS

We enrolled 19 women with anorexia nervosa and 19 healthy controls in our study. Patients with anorexia nervosa showed significant FA decreases in the parietal part of the left superior longitudinal fasciculus (SLF; p(FWE) < 0.05), with increased MD and RD but no differences in AD. Patients with anorexia nervosa also showed significantly increased MD in the fornix (p(FWE) < 0.05), accompanied by decreased FA and increased RD and AD.

LIMITATIONS

Limitations include our modest sample size and cross-sectional design.

CONCLUSION

Our findings support the presence of white matter pathology in patients with anorexia nervosa. Alterations in the SLF and fornix might be relevant to key symptoms of anorexia nervosa, such as body image distortion or impairments in body-energy-balance and reward processes. The differences found in both areas replicate those found in previous DTI studies and support a role for white matter pathology of specific neural circuits in individuals with anorexia nervosa.

Effects of obstetric complications on volume and functional connectivity of striatum in anorexia nervosa patients

OBJECTIVE

To investigate the volume and functional connectivity of dorsal and ventral striatal nuclei in anorexia nervosa (AN) and their relationship with early exposure to obstetric complications.

METHOD

Fifty-one patients with lifetime AN (35 acute, 16 recovered) and 34 healthy controls underwent high-resolution and resting-state functional magnetic resonance imaging.

RESULTS

The AN group showed reduced functional connectivity of the putamen compared with healthy women, and this reduction was more evident in patients with lifetime binge eating/purging. Both acute and recovered AN groups showed a larger left accumbens area compared with that of healthy women. The functional connectivity of bilateral nucleus accumbens and putamen showed significant negative correlations with number of obstetric complications in the AN group.

DISCUSSION

This study supports the hypothesis that AN is associated with structural and functional alterations of striatal networks, and reveals the possible role of obstetric complications in the pathogenesis of striatal dysfunction.

Alterations in brain structure in adults with anorexia nervosa and the impact of illness duration

BACKGROUND

Brain structure alterations have been reported in anorexia nervosa, but findings have been inconsistent. This may be due to inadequate sample size, sample heterogeneity or differences in methodology.

METHOD

High resolution magnetic resonance images were acquired of 33 adult participants with anorexia nervosa and 33 healthy participants, the largest study sample to date, in order to assess whole-brain volume, ventricular cerebrospinal fluid, white matter and grey matter volume. Voxel-based morphometry was conducted to assess regional grey matter volume. Levels of depression, anxiety, obsessionality and eating disorder-related symptoms were measured and used to explore correlations with brain structure.

RESULTS

Participants with anorexia nervosa had smaller brain volumes as well as a global decrease in grey matter volume with ventricular enlargement. Voxel-based morphometry revealed a decrease in grey matter volume spanning across the cerebellum, temporal, frontal and occipital lobes. A correlation was found between grey matter volume loss and duration of illness in the cerebellum and mesencephalon. No correlations were found with clinical measures.

CONCLUSIONS

Findings are in accordance with several previous studies on brain structure and match functional studies that have assessed the symptomatology of anorexia nervosa, such as body image distortion and cognitive bias to food. The correlation with duration of illness supports the implication of cerebellar atrophy in the maintenance of low weight and disrupted eating behaviour and illustrates its role in the chronic phase of anorexia nervosa. The lack of other correlations suggests that these findings are not related to the presence of co-morbid disorders.

Metabolic imaging of deep brain stimulation in anorexia nervosa: a 18F-FDG PET/CT study

OBJECTIVES

Anorexia nervosa (AN), a disorder of unknown etiology, has the highest mortality rate of any psychiatric disorder. Drawing the brain metabolic pattern of AN may help to target the core biological and psychological features of the disorder and to perfect the diagnosis and recovery criteria. In this study, we used 18F-FDG PET to show brain metabolic network for AN.

METHODS

Glucose metabolism in 6 AN patients and 12 age-matched healthy controls was studied using 18F-FDG PET. SPM2 was used to compare brain metabolism in AN patients with that in healthy controls. Four of 6 AN patients took deep brain stimulation (DBS) targeted in nucleus accumbens (NAcc). About 3 to 6 months after the surgery, the 4 AN patients took another 18F-FDG PET scan to assess the change in brain glucose metabolism.

RESULTS

The SPM (statistical parametric mapping ) analysis showed hypermetabolism in the frontal lobe (bilateral, BA10, BA11, BA47), the limbic lobe (bilateral, hippocampus, and amygdala), lentiform nucleus (bilateral), left insula (BA13), and left subcallosal gyrus (BA25). It also showed hypometabolism in the parietal lobe (bilateral, BA7, BA40). The hypermetabolism in frontal lobe, hippocampus, and lentiform nucleus decreased after NAcc-DBS.

CONCLUSIONS

The changes in brain glucose metabolism illustrated the brain metabolic pattern in AN patients. Furthermore, the pattern can be modulated by NAcc-DBS, which confirmed specificity of the pattern. The regions with altered metabolism could interconnect to form a network and integrate information related to appetite. Our study may provide information for targeting the potential candidate brain regions for understanding the pathophysiology of AN and assessing the effects of existing and future treatment approaches.

Annual research review: The neurobehavioral development of multiple memory systems--implications for childhood and adolescent psychiatric disorders

Extensive evidence indicates that mammalian memory is organized into multiple brains systems, including a 'cognitive' memory system that depends on the hippocampus and a stimulus-response 'habit' memory system that depends on the dorsolateral striatum. Dorsal striatal-dependent habit memory may in part influence the development and expression of some human psychopathologies, particularly those characterized by strong habit-like behavioral features. The present review considers this hypothesis as it pertains to psychopathologies that typically emerge during childhood and adolescence. These disorders include Tourette syndrome, attention-deficit/hyperactivity disorder, obsessive-compulsive disorder, eating disorders, and autism spectrum disorders. Human and nonhuman animal research shows that the typical development of memory systems comprises the early maturation of striatal-dependent habit memory and the relatively late maturation of hippocampal-dependent cognitive memory. We speculate that the differing rates of development of these memory systems may in part contribute to the early emergence of habit-like symptoms in childhood and adolescence. In addition, abnormalities in hippocampal and striatal brain regions have been observed consistently in youth with these disorders, suggesting that the aberrant development of memory systems may also contribute to the emergence of habit-like symptoms as core pathological features of these illnesses. Considering these disorders within the context of multiple memory systems may help elucidate the pathogenesis of habit-like symptoms in childhood and adolescence, and lead to novel treatments that lessen the habit-like behavioral features of these disorders.

Intellectual function in patients with anorexia nervosa and bulimia nervosa

OBJECTIVE

This study aimed to examine cognitive function in individuals with anorexia nervosa (AN) and bulimia nervosa (BN) on the basis of IQ measures, indexes and subtests of the Wechsler Adult Intelligence Scale – Third Edition (WAIS-III).

METHODS

A total of 41 patients with AN, 40 patients with BN and 40 healthy controls (HC), matched for sex, age and education, were recruited consecutively to complete the WAIS-III.

RESULTS

The AN group showed a significantly lower performance than the HC group on most global measures and on eight of the 13 administered subtests. Minor differences in verbal function were detected between the BN group and the HC group.

CONCLUSION

The patients with eating disorders showed normal intellectual functions compared with the normative population. However, the AN group displayed a consistently lower performance than the matched HC group, which performed above normative means. The BN group performed at a level between that of the AN and HC groups.

The neurobiology of anorexia nervosa: a systematic review

OBJECTIVE

Recent advances in neuroimaging techniques have enabled a better understanding of the neurobiological underpinnings of anorexia nervosa (AN). The aim of this paper was to summarise our current understanding of the neurobiology of AN.

METHODS

The literature was searched using the electronic databases PubMed and Google Scholar, and by additional hand searches through reference lists and specialist eating disorders journals. Relevant studies were included if they were written in English, only used human participants, had a specific AN group, used clinical populations of AN, group comparisons were reported for AN compared to healthy controls and not merely AN compared to other eating disorders or other psychiatric groups, and were not case studies.

RESULTS

The systematic review summarises a number of structural and functional brain differences which are reported in individuals with AN, including differences in neurotransmitter function, regional cerebral blood flow, glucose metabolism, volumetrics and the blood oxygen level dependent response.

CONCLUSION

Several structural and functional differences have been reported in AN, some of which reverse and others which persist following weight restoration. These findings have important implications for our understanding of the neurobiological underpinnings of AN, and further research in this field may provide new direction for the development of more effective treatments.

Morphological Changes in the Brain of Acutely Ill and Weight-Recovered Patients with Anorexia Nervosa

Objective: Acute anorexia nervosa (AN) leads to reduced gray (GM) and white matter (WM) volume in the brain, which however improves again upon restoration of weight. Yet little is known about the extent and clinical correlates of these brain changes, nor do we know much about the time-course and completeness of their recovery. Methods: We conducted a meta-analysis and a qualitative review of all magnetic resonance imaging studies involving volume analyses of the brain in both acute and recovered AN. Results: We identified structural neuroimaging studies with a total of 214 acute AN patients and 177 weight-recovered AN patients. In acute AN, GM was reduced by 5.6% and WM by 3.8% compared to healthy controls (HC). Short-term weight recovery 2–5 months after admission resulted in restitution of about half of the GM aberrations and almost full WM recovery. After 2–8 years of remission GM and WM were nearly normalized, and differences to HC (GM: –1.0%, WM: –0.7%) were no longer significant, although small residual changes could not be ruled out. In the qualitative review some studies found GM volume loss to be associated with cognitive deficits and clinical prognosis. Conclusions: GM and WM were strongly reduced in acute AN. The completeness of brain volume rehabilitation remained equivocal.

Brain volumetric abnormalities in patients with anorexia and bulimia nervosa: a voxel-based morphometry study

Recent studies focussing on neuroimaging features of eating disorders have observed that anorexia nervosa (AN) is characterized by significant grey matter (GM) atrophy in many brain regions, especially in the cerebellum and anterior cingulate cortex. To date, no studies have found GM atrophy in bulimia nervosa (BN) or have directly compared patients with AN and BN. We used voxel-based morphometry (VBM) to characterize brain abnormalities in AN and BN patients, comparing them with each other and with a control group, and correlating brain volume with clinical features. We recruited 17 AN, 13 BN and 14 healthy controls. All subjects underwent high-resolution magnetic resonance imaging (MRI) with a T1-weighted 3D image. VBM analysis was carried out with the FSL-VBM 4.1 tool. We found no global atrophy, but regional GM reduction in AN with respect to controls and BN in the cerebellum, fusiform area, supplementary motor area, and occipital cortex, and in the caudate in BN compared to AN and controls. Both groups of patients had a volumetric increase bilaterally in somatosensory regions with respect to controls, in areas that are typically involved in the sensory-motor integration of body stimuli and in mental representation of the body image. Our VBM study documented, for the first time in BN patients, the presence of volumetric alterations and replicated previous findings in AN patients. We evidenced morphological differences between AN and BN, demonstrating in the latter atrophy of the caudate nucleus, a region involved in reward mechanisms and processes of self-regulation, perhaps involved in the genesis of the binge-eating behaviors of this disorder.

Anorexia nervosa is linked to reduced brain structure in reward and somatosensory regions: a meta-analysis of VBM studies

BACKGROUND

Structural imaging studies demonstrate brain tissue abnormalities in eating disorders, yet a quantitative analysis has not been done.

METHODS

In global and regional meta-analyses of 9 voxel-based morphometry (VBM) studies, with a total of 228 eating disorder participants (currently ill with anorexia nervosa), and 240 age-matched healthy controls, we compare brain volumes using global and regional analyses.

RESULTS

Anorexia nervosa (AN) patients have global reductions in gray (effect size = -0.66) and white matter (effect size = -0.74) and increased cerebrospinal fluid (effect size = 0.98) and have regional decreases in left hypothalamus, left inferior parietal lobe, right lentiform nucleus and right caudate, and no significant increases. No significant difference in hemispheric lateralization was found.

CONCLUSIONS

Global and regional meta-analyses suggest that excessive restrained eating as found in those with anorexia nervosa coincides with structural brain changes analogous to clinical symptoms.

Allocentric lock in anorexia nervosa: new evidences from neuroimaging studies

Individuals with anorexia nervosa (AN) have a disturbance in the way in which their body is experienced and tend to evaluate negatively their own body and body parts. It is controversial whether these symptoms are secondary to dysfunctions in the neuronal processes related to appetite and emotional regulation or reflect a primary disturbance in the way the body is experienced and remembered. According to the "Allocentric Lock Hypothesis--ALH" (http://dx.doi.org/10.1016/j.mehy.2011.10.039) individuals with AN may be locked to an allocentric (observer view) negative memory of the body that is no more updated by contrasting egocentric representations driven by perception. Recent neuroimaging studies are showing several structural and functional alterations in frame- and memory-related body-image-processing brain circuits that may support ALH.