Structural brain patterns in Anorexia Nervosa: a multimodal MRI evaluation

Introduction. 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.