Shift Toward Randomness in Brain Networks of Patients With Anorexia Nervosa: The Role of Malnutrition

Abstract

No 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.

Large-Scale Exploration of Whole-Brain Structural Connectivity in Anorexia Nervosa: Alterations in the Connectivity of Frontal and Subcortical Networks

“…The collection of results from this investigation may reflect alterations in global properties of brain organization in AN that hinder adaptive cognition and behavior generally -for example contributing to general psychopathology (e.g., anxiety, depression) or limiting cognitive function (e.g., memory and learning). Two smaller studies have indicated alterations in global brain organization in AN (23,24), and replicating this work in a larger sample comprises a valuable direction for future research. Disrupted rich club organization has been observed in multiple psychiatric disorders, including major depressive disorder (57), OCD (58) and schizophrenia (59).…”

“…The tract reconstruction method of the prior study was limited by assuming a single fiber direction per voxel, resulting in a less biologically accurate reconstruction of white matter pathways relative to the multi-fiber probabilistic approach of the current study (15)(16)(17). Three smaller studies assessed brain-wide structural connectivity and organization in AN using graphbased approaches (23)(24)(25). The only study using probabilistic tractography to recover white matter connections also assessed node-connectivity (23).…”

“…These methods provide different information about brain organization, and using them together can provide detailed information about localized abnormalities in AN that may be probed further. Graph theory approaches have been applied in AN (14,(23)(24)(25) however this study is the first to simultaneously probe the connectivity of subnetworks and nodes.…”

Large-scale exploration of whole-brain structural connectivity in anorexia nervosa: alterations in the connectivity of frontal and subcortical networks

“…Three smaller studies assessed brain-wide structural connectivity and organization in AN using graph-based approaches (23-25). The only study using probabilistic tractography to recover white matter connections also assessed node-connectivity (23). Inferences from this study (23), including reduced connectivity of frontal brain regions in AN, are largely inconsistent with outcomes of the current investigation.…”

Complex functional brain network properties in anorexia nervosa

“…As centrality accounts for the relationship of the brain region’s properties with the entire functional connectome, brain regions with greater functional centrality indicate a greater amount of influence on the functional performance of the network [ 25 ]. Some recent work has been done investigating the structural [ 26 ] and functional [ 27 – 30 ] connectomes using graph theory approaches, and a recent review has shown nodal topological differences in brain regions including the insula, thalamus, basal ganglia, posterior occipital cortex, prefrontal cortex, inferior frontal gyrus, and precentral gyrus have been altered [ 31 ].…”