Interhemispheric functional connectivity in anorexia and bulimia nervosa

IntroductionThe functional interplay between brain hemispheres is fundamental for behavioral, cognitive and emotional control. Several pathophysiological aspects of eating disorders (EDs) have been investigated by the use of functional Magnetic Resonance Imaging (fMRI).ObjectivesThe objective of the study was to investigate functional brain asymmetry of resting-state fMRI correlations in symptomatic patients with anorexia nervosa (AN) and bulimia nervosa (BN).AimsWe aimed at revealing whether brain regions implicated in reward, cognitive control, starvation and emotion regulation show altered inter-hemispheric functional connectivity in patients with AN and BN.MethodsUsing resting-state fMRI, voxel-mirrored homotopic connectivity (VMHC) and regional inter-hemispheric spectral coherence (IHSC) analyses in two canonical slow frequency bands (“Slow-5”, “Slow-4”) were studied in 15AN and 13BN patients and 16 healthy controls (HC). Using T1-weighted and diffusion tensor imaging MRI scans, regional VMHC values were correlated with the left-right asymmetry of corresponding homotopic gray matter volumes and with the white matter callosal fractional anisotropy (FA).ResultsCompared to HC, AN patients exhibited reduced VMHC in cerebellum, insula and precuneus, while BN patients showed reduced VMHC in dorso-lateral prefrontal and orbito-frontal cortices. The regional IHSC analysis highlighted that the inter-hemispheric functional connectivity was higher in the ‘Slow-5′Band in all regions except the insula. No group differences in left-right structural asymmetries and in VMHC vs callosal FA correlations were found.ConclusionsThese anomalies indicate that AN and BN, at least in their acute phase, are associated with a loss of inter-hemispheric connectivity in regions implicated in self-referential, cognitive control and reward processing.Disclosure of interestThe authors have not supplied their declaration of competing interest.