Evidence for alterations of cortical folding in anorexia nervosa

Sulcal characteristics patterns and gyrification gradient at different stages of Anorexia Nervosa: A structural MRI evaluation

Previous research evidenced alterations of different cortical parameters in patients with acute Anorexia Nervosa (AN), but no study to date investigated the morphology of individual sulci and their relationship with other structural indices. Our study aims at exploring the depth and width of 16 major cortical sulci in AN at different stages of the disorder and their relationships with the gyrification gradient. Two samples were included in the study. The first involved 38 patients with acute AN, 20 who fully recovered from AN, and 38 healthy women (HW); the second included 16 patients with AN and 16 HW. Sulcal width and depth were estimated for 16 sulci and outlined with a factorial analysis. An anterior-posterior gradient of gyrification was also extracted. Compared to HW, patients with acute AN displayed higher width and depth values in specific cortical sulci, and an altered gyrification gradient in areas encompassing the Central Sulcus, and Parieto-Temporal and Frontal Lobe regions. Sulcal width negatively correlated with gyrification gradient in areas where these values are altered in AN patients. Our results suggest the presence of alterations in sulcal morphology with a pattern similar to the gyrification gradient one and which seems to be related with malnutrition.

Ectodermal disturbance in development shared by anorexia and schizophrenia may reflect neurodevelopmental abnormalities

Minor physical abnormalities (MPA) are subtle dysmorphic features of bodily structures that have little or no impact on function. Most MPA develop during the first gestational trimester and are considered as important indicators of neuroectodermal deficiencies emerging during early brain development. A higher frequency of MPA was confirmed in schizophrenia patients and their relatives, when compared to controls. These findings are consistent with the neurodevelopmental model of schizophrenia. A neurodevelopmental component amongst other risk factors has also been recently proposed for anorexia nervosa (AN). The current study aimed to assess MPA frequency in adolescent inpatients with either schizophrenia spectrum disorders (SSD) or AN as compared to healthy controls (HC). The Waldrop Scale was used for assessing MPA. The mean MPA total score and mean head subscore was significantly higher in both test groups than in HC. There were no statistically significant differences between SSD and AN groups. The MPA profile (not frequency) was similar in all three groups. This finding is consistent both with widely acknowledged neurodevelopmental schizophrenia hypothesis as well as with more recent neurodevelopmental model of AN. Nevertheless, the findings should not be overgeneralized and further studies are warranted.

Cortical thinning and associated connectivity changes in patients with anorexia nervosa

Structural brain abnormalities are a consistent finding in anorexia nervosa (AN) and proposed as a state biomarker of the disorder. Yet little is known about how regional structural changes affect intrinsic resting-state functional brain connectivity (rsFC). Using a cross-sectional, multimodal imaging approach, we investigated the association between regional cortical thickness abnormalities and rsFC in AN. Twenty-two acute AN patients and twenty-six age- and gender-matched healthy controls underwent a resting-state functional magnetic resonance imaging scan and cognitive tests. We performed group comparisons of whole-brain cortical thickness, seed-based rsFC, and network-based statistical (NBS) analyses. AN patients showed cortical thinning in the precuneus and inferior parietal lobules, regions involved in visuospatial memory and imagery. Cortical thickness in the precuneus correlated with nutritional state and cognitive functions in AN, strengthening the evidence for a critical role of this region in the disorder. Cortical thinning was accompanied by functional connectivity reductions in major brain networks, namely default mode, sensorimotor and visual networks. Similar to the seed-based approach, the NBS analysis revealed a single network of reduced functional connectivity in patients, comprising mainly sensorimotor- occipital regions. Our findings provide evidence that structural and functional brain abnormalities in AN are confined to specific regions and networks involved in visuospatial and somatosensory processing. We show that structural changes of the precuneus are linked to nutritional and functional states in AN, and future longitudinal research should assess how precuneus changes might be related to the evolution of the disorder.

Descriptions of Disordered Eating in German Psychiatric Textbooks, 1803-2017

The most common eating disorders (EDs) according to DSM-5 are anorexia nervosa (AN), bulimia nervosa (BN) and binge eating disorder (BED). These disorders have received increasing attention in psychiatry due to rising prevalence and high morbidity and mortality. The diagnostic category "anorexia nervosa," introduced by Ernest-Charles Lasègue and William Gull in 1873, first appears a century later in a German textbook of psychiatry, authored by Gerd Huber in 1974. However, disordered eating behavior has been described and discussed in German psychiatric textbooks throughout the past 200 years. We reviewed content regarding eating disorder diagnoses but also descriptions of disordered eating behavior in general. As material, we carefully selected eighteen German-language textbooks of psychiatry across the period 1803-2017. Previously, in German psychiatry, disordered eating behaviors were seen as symptoms of depressive disorders, bipolar disorder or schizophrenia, or as manifestations of historical diagnoses no longer used by the majority of psychiatrists such as neurasthenia, hypochondria and hysteria. Interestingly, 19th and early 20th century psychiatrists like Kraepelin, Bumke, Hoff, Bleuler, and Jaspers reported symptom clusters such as food refusal and vomiting under these outdated diagnostic categories, whereas nowadays they are listed as core criteria for specific eating disorder subtypes. A wide range of medical conditions such as endocrinopathies, intestinal or brain lesions were also cited as causes of abnormal food intake and body weight. An additional consideration in the delayed adoption of eating disorder diagnoses in German psychiatry is that people with EDs are commonly treated in the specialty discipline of psychosomatic medicine, introduced in Germany after World War II, rather than in psychiatry. Viewed from today's perspective, the classification of disorders associated with disordered eating is continuously evolving. Major depressive disorder, schizophrenia and physical diseases have been enduringly associated with abnormal eating behavior and are listed as important differential diagnoses of EDs in DSM-5. Moreover, there are overlaps regarding the neurobiological basis and psychological and psychopharmacological therapies applied to all of these disorders.

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.

Integrative Genomic Enrichment Analysis Identified the Brain Regions and Development Stages Related to Anorexia Nervosa and Obsessive-Compulsive Disorder

Our aim is to explore the spatial and temporal features of anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) considering different brain regions and development stages. The gene sets related to 16 brain regions and nine development stages were obtained from a brain spatial and temporal transcriptomic dataset. Using the genome-wide association study data, transcriptome-wide association study (TWAS) was conducted to identify the genes whose imputed expressions were associated with AN and OCD, respectively. The mRNA expression profiles were analyzed by GEO2R to obtain differentially expressed genes. Gene set enrichment analysis was conducted to detect the spatial and temporal features related to AN and OCD using the TWAS and mRNA expression analysis results. We observed multiple common association signals shared by TWAS and mRNA expression analysis of AN, such as the primary auditory cortex vs. cerebellar cortex in fetal development and earlier vs. later fetal development in the somatosensory cortex. For OCD, we also detected multiple common association signals, such as medial prefrontal cortex vs. amygdala in adulthood and fetal development vs. infancy in mediodorsal nucleus of thalamus. Our study provides novel clues for describing the spatial and temporal features of brain development in the pathogenesis of AN and OCD.

Cortical Complexity in Anorexia Nervosa: A Fractal Dimension Analysis

Fractal Dimension (FD) has shown to be a promising means to describe the morphology of cortical structures across different neurologic and psychiatric conditions, displaying a good sensitivity in capturing atrophy processes. In this study, we aimed at exploring the morphology of cortical areas by means of FD in 58 female patients with Anorexia Nervosa (AN) (38 currently underweight and 20 fully recovered) and 38 healthy controls (HC). All participants underwent high-resolution MRI. Surface extraction was completed using FreeSurfer, FD was computed using the calcFD toolbox. The whole cortex mean FD value was lower in acute AN patients compared to HC (p < 0.001). Recovered AN patients did not show differences in the global FD when compared to HC. However, some brain areas showed higher FD in patients than controls, while others showed the opposite pattern. Parietal regions showed lower FD in both AN groups. In acute AN patients, the FD correlated with age (p < 0.001), body mass index (p = 0.019) and duration of illness (p = 0.011). FD seems to represent a feasible method to explore cortical complexity in patients with AN since it demonstrated to be sensitive to the effects of both severity and duration of malnutrition.

Cortical morphometry in anorexia nervosa: An out-of-sample replication study

BACKGROUND

Acute anorexia nervosa (AN) is frequently accompanied by reduced global cortical volume. Investigations of local cortical alterations in AN have revealed widespread reduction in cortical thickness, gyrification, and curvature. The aim of the present study was to combine data from two previous studies to replicate previous findings.

METHODOLOGY

Magnetic resonance imaging (MRI) images from 46 adult women with AN and 54 age-matched healthy comparison (HC) women were analysed using FreeSurfer. Group differences in cortical volume and local cortical measures, including gyrification, curvature, thickness, and area, were examined controlling for dataset and age.

RESULTS

The AN group had reduced global cortical volume relative to the HC group. The AN group also had reduction in local cortical gyrification, small localised clusters of reduced cortical thickness, in the occipital and parietal cortices, and surface area in the frontal and temporal cortices. The AN group also had increased cortical thickness in the ACC relative to the HC participants.

CONCLUSIONS

The present findings replicate and validate previous findings of reduced global cortical volume and local gyrification in acute AN. The findings highlight the need for further investigation of local cortical folding, thickness, and surface area in AN to gain further insight into the biological underpinnings of AN.

Nutritional Status Affects Cortical Folding: Lessons Learned From Anorexia Nervosa

BACKGROUND

Cortical folding is thought to remain relatively invariant after birth. Therefore, differences seen in psychiatric disorders have been proposed as early biomarkers or used as intermediate phenotypes in imaging genetics studies. Anorexia nervosa (AN) is associated with drastic and rapid structural brain alterations and thus may be an ideal model disorder to study environmental influences on cortical folding.

METHODS

To date, the only two studies in AN applied different methods (local gyrification index and mean curvature) and found seemingly discordant results. We computed both vertexwise measures in a sizable sample of acutely underweight female AN patients (n = 87, mean age 16.5 years), long-term recovered patients (n = 58, mean age 22 years), and healthy control participants (n = 141, mean age 19.5 years). The majority of acutely ill patients were scanned longitudinally (n = 57) again after partial weight normalization (>14% body mass index increase).

RESULTS

While gyrification was broadly reduced in acutely ill patients, normal values were restored in most brain regions after partial weight restoration (≈3 months), and after full recovery no significant differences were evident relative to control participants. Increased gyrification was largely predicted by weight restoration alone. Results for absolute mean curvature analyses complemented those obtained using the local gyrification index.

CONCLUSIONS

Together, these findings indicate that nutritional status affects cortical folding and suggest that gyrification studies may need to better control for environmental factors. Moreover, they provide novel support for the likelihood that macroscopic changes in the cortical organization in AN are more reflective of nutritional state than premorbid trait markers or permanent scars.

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.

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.