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Structural brain patterns in Anorexia Nervosa: a multimodal MRI evaluation
Full text linkIntroduction.
Cortical and white matter structural abnormalities in Anorexia Nervosa (AN) have been recently investigated, but no attempt has been made to explore the organizational patterns that govern the relationships between different brain areas and to characterize the neurobiology of the disorder in the different stages of its course. Aims of the present work are to characterize cortical and white matter network architecture by means of different structural indices and computational techniques, to observe the presence of any correlation between clinical variables and networks characteristics and to investigate the structural organizational patterns in the different stage of AN course.
Methods and Materials.
38 patients with acute AN, 38 healthy controls and 20 patients in full remission from AN were included in this study. All participants underwent high-resolution MRI. An analysis of cortical structural co-variance was performed using cortical thickness and gyrification indices. The anatomical complexity of the cortex was explored by means of Fractal Dimension (FD). Connectomic tools were applied to DTI tractography data to investigate the white matter network architecture.
Results.
Patients with AN showed unbalanced integration and segregation properties in cortical thickness, gyrification and DTI networks both on global and regional levels. Patients with a poor outcome at a three years follow-up assessment showed higher segregation measures and lower small-worldness in the gyrification network. The FD analysis revealed a reduced cortical complexity in the AN group.
Discussion.
Alterations in structural covariance patterns in AN are likely to reflect the metabolic consequences of the disorder as well as deviations in normal developmental trajectories. Lower FD in AN indicates a reduction of cortical complexity in the acute stages of the disorder and evidenced that this structural index is sensitive to the effects of malnutrition
Anorexia nervosa and diffusion weighted imaging: An open methodological question raised by a systematic review and a fractional anisotropy anatomical likelihood estimation meta‐analysis
No full textBACKGROUND:
Anorexia nervosa (AN) is characterized by white matter abnormalities in neuroimaging studies. Fractional anisotropy (FA) is a diffusion tensor imaging (DTI) index that is considered an instrument for the evaluation of white matter alterations. However, the literature has recently pointed out the role of the partial volume effect (PVE) as a confounding factor for the identification of juxtaposed tissues. Our goal was to review the DTI literature in AN and evaluate possible confounding factors linked to the reported results.
METHOD:
A systematic review of the literature was conducted to identify Diffusion Tensor Imaging studies of individuals with AN and, subsequently, an anatomical likelihood estimation (ALE) meta-analysis was performed on studies published before March 18, 2019.
RESULTS:
Twenty-four studies (AN = 517, controls = 542) were included in the qualitative systematic review of the literature. Ten published studies underwent the ALE-analysis (AN = 210, controls = 229), plus data from an unpublished cohort (AN = 38, controls = 38). Two clusters of decreased FA were identified, namely in the left corona radiata, and in the left thalamus. Only one article took the PVE correction analysis into account.
CONCLUSIONS:
The alterations identified must be considered within the limits of a possible methodological bias regarding PVE and free water and re-analysis of the data may be recommended. The preliminary data showed that the alteration of white matter pathways between the limbic structures and brain cortex may be linked to the processing of somatosensory information that could play a key role in the psychopathology of the disorde
Network analysis of specific psychopathology and psychiatric symptoms in patients with anorexia nervosa
No full textBACKGROUND:
Network analysis is increasingly applied to psychiatric populations to understand relationships among symptoms.
METHODS:
Network analysis was applied on 955 patients with anorexia nervosa (AN; 631 restricting-type [ANR] and 324 binge eating-/purging-type [ANBP]), assessed with Symptom Check-List 90 (SCL-90), Eating Disorder Inventory (EDI), and Tridimensional Personality Questionnaire.
RESULTS:
Depression, anxiety, interpersonal sensitivity (SCL-90), and ineffectiveness (EDI) had the highest centrality (strength from 1.19 to 1.35 in ANBP, and from 1.15 to 1.51 in ANR). Body mass index (BMI) had low centrality (0.14 ANBP and 0.41 ANR). Drive for thinness showed the strongest correlation with central nodes in ANBP (correlation around 0.44) and ANR (correlation range 0.38-0.47), and drive for thinness had higher centrality in ANR (1.15) than in ANBP (0.81), whereas body dissatisfaction in ANBP (0.73) than in ANR (0.61).
DISCUSSION:
In addition to ED-core symptoms, psychiatric comorbid symptoms should be the focus of specific treatments in patients with AN, independently from BMI
Shift Toward Randomness in Brain Networks of Patients With Anorexia Nervosa: The Role of Malnutrition
Full text linkNo study to date investigated structural white matter (WM) connectome characteristics in patients with anorexia nervosa (AN). Previous research in AN found evidence of imbalances in global and regional connectomic brain architecture and highlighted a role of malnutrition in determining structural brain changes. The aim of our study was to explore the characteristics of the WM network architecture in a sample of patients with AN. Thirty-six patients with AN and 36 healthy women underwent magnetic resonance imaging to obtain a high-resolution three-dimensional T1-weighted anatomical image and a diffusion tensor imaging scan. Probabilistic tractography data were extracted and analyzed in their network properties through graph theory tools. In comparison to healthy women, patients with AN showed lower global network segregation (normalized clustering: p = 0.029), an imbalance between global network integration and segregation (i.e., lower small-worldness: p = 0.031), and the loss of some of the most integrative and influential hubs. Both clustering and small-worldness correlated with the lowest lifetime body mass index. A significant relationship was found between the average regional loss of cortical volume and changes in network properties of brain nodes: the more the difference in the cortical volume of brain areas, the more the increase in the centrality of corresponding nodes in the whole brain, and the decrease in clustering and efficiency of the nodes of parietal cortex. Our findings showed an unbalanced connectome wiring in AN patients, which seems to be influenced by malnutrition and loss of cortical volume. The role of this rearrangement in the maintenance and prognosis of AN and its reversibility with clinical improvement needs to be established by future studies
Brain gyrification in bipolar disorder: a systematic review of neuroimaging studies
Full text linkBipolar disorder (BD) is a severe mental illness with a strong genetic component. Genetic variations have been involved in the risk of this disorder, including those mediating brain function and neurodevelopment. Early neurodevelopment and neuroprogression processes could be reflected in brain gyrification patterns and help optimize the prediction and diagnosis of such disorders that is often delayed. Previous neuroimaging studies using this measure in patients with bipolar disorder revealed controversial results. This systematic review aimed to summarize available neuroimaging investigations on gyrification in BD compared to healthy controls (HC) and/or other psychiatric groups. Fourteen studies including 733 patients with BD, 585 patients with schizophrenia (SCZ), 90 with schizoaffective disorder (SZA), and 1380 healthy subjects were identified. Overall, a heterogeneous pattern of gyrification emerged between patients with BD and HC. Interestingly, increased gyrification or no differences were also observed in patients with BD compared to those with the schizophrenia-spectrum disorders. Furthermore, relatives of patients with BD showed lower or no differences in gyrification compared to healthy subjects without a family history of affective illness. Differences in the design and in methodological approaches could have contributed to the heterogeneity of the findings. The current review supports an altered brain gyrification pattern that underlies the pathophysiology of BD spanning large anatomical and functional neural networks, associated with altered cognitive functioning, difficulties in processing and affective regulation, and clinical symptoms. Longitudinal studies are needed to test different bipolar phenotypes and pharmacological effects on gyrification. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11682-022-00713-x
Virtual reality assessment of a high-calorie food bias: Replication and food-specificity in healthy participants
Full text linkBrain networks in eating disorders: a systematic review of graph theory studies
Full text linkPURPOSE: Recent evidence from neuroimaging research has shown that eating disorders (EDs) are characterized by alterations in interconnected neural systems, whose characteristics can be usefully described by connectomics tools. The present paper aimed to review the neuroimaging literature in EDs employing connectomic tools, and, specifically, graph theory analysis.METHODS: A systematic review of the literature was conducted to identify studies employing graph theory analysis on patients with eating disorders published before the 22nd of June 2020.RESULTS: Twelve studies were included in the systematic review. Ten of them address anorexia nervosa (AN) (AN=199; acute AN=85, weight recovered AN with acute diagnosis=24; fully recovered AN=90). The remaining two articles address patients with bulimia nervosa (BN) (BN=48). Global and regional unbalance in segregation and integration properties were described in both disorders.DISCUSSION: The literature concerning the use of connectomics tools in EDs evidenced the presence of alterations in the topological characteristics of brain networks at a global and at a regional level. Changes in local characteristics involve areas that have been demonstrated to be crucial in the neurobiology and pathophysiology of EDs. Regional imbalances in network properties seem to reflect on global patterns.LEVEL OF EVIDENCE: Level I, systematic review
Persistent avoidance of virtual food in anorexia nervosa-restrictive type: Results from motion tracking in a virtual stopping task
Full text linkObjectiveFood avoidance is central to patients with anorexia nervosa-restrictive type (AN-R). Competing accounts in experimental psychopathology research suggest that food avoidance may result from automatic, habitual responses or from elevated inhibitory control abilities. This study investigated behavioral trajectories of food avoidance in a novel virtual reality stopping task.MethodSixty patients with AN-R and 29 healthy controls with normal weight were investigated using a novel, kinematic task in virtual reality. We recorded spatial displacement in stop- and go-trials to virtual food and control objects. Inhibitory control abilities were operationalized by the VR task in stopping performance (i.e., interrupted movement in stop-trials), whereas we also measured habitual avoidance of virtual food across both go- and stop-trials (i.e., delayed movement relative to nonfood objects).ResultsIn patients with AN-R, hand displacements were shorter to food versus nonfood across stop- and go-trials, reflected in a Stimulus x Group interaction. Healthy controls showed no differences. Importantly, the food-specific effect in AN-R was identical across stop- and go-trials, indicating habitual food avoidance. Moreover, stop error rates (i.e., stop-trials with response) were lower in patients with AN-R.DiscussionThe findings suggest food-specific habitual avoidance and heightened generalized inhibitory control in AN-R. The continuously delayed displacements during active hand movements across stop- and go-trials indicated the persistence of patients' avoidance of food.Public SignificanceExperimental research investigates the mechanisms underlying mental disorders such as anorexia nervosa. In this study, we measured interrupted hand movements in response to food pictures or neutral pictures (shoes) in patients with anorexia nervosa and healthy controls. A virtual reality scenario was used. Findings indicated that patients were slower at approaching food, interrupted or not. Key mechanisms of food avoidance can be translated into habit-based treatment options in future research
Eyes on the body: Assessing attentional bias toward body-related stimuli in Anorexia Nervosa
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