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.
Highlights
The neurobiological characterization of anorexia nervosa (AN) through structural and functional neuroimaging techniques suggests that the complex array of symptoms characterizing AN emerges from failures in the relations between multiple areas rather than from distinct regional alterations (Frank, 2014; Steward et al, 2017)
Our data provide evidence of the presence of reduced smallworld properties in patients with AN, which seems to be driven by a reduction in global clusterization of the brain networks
As the clusterization of the connectome indicates its tendency to be composed of densely connected and functionally coherent neuronal units (Bullmore and Sporns, 2009), higher clustering levels reflect an increase in the network regularity, whereas lower levels of segregation usually reveal a shift toward more random configurations (Bassett and Bullmore, 2006; Rubinov and Sporns, 2010)
Summary
The neurobiological characterization of anorexia nervosa (AN) through structural and functional neuroimaging techniques suggests that the complex array of symptoms characterizing AN emerges from failures in the relations between multiple areas rather than from distinct regional alterations (Frank, 2014; Steward et al, 2017). The presence of alterations in the connectivity between topologically distributed areas has suggested that AN is characterized by imbalances in the properties that regulate their functional and structural integration. One of the most relevant contributions of connectomic analysis is its ability to identify the most influential and connected regions within the brain. These regions are called hubs and were shown to be vulnerable and sensitive to pathogenic mechanisms affecting the brain and are likely to spread disorder-related processes to other brain areas (Rubinov and Sporns, 2010; Fornito et al, 2017)
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