Multimodal quantitative magnetic resonance imaging alterations of the basal ganglia circuit underlie the severity of bulimia nervosa.

Background: Neuroimaging alterations in the basal ganglia circuit have been reported to correlate with the severity of various eating or addictive disorders, but their relationship to the severity of bulimia nervosa (BN) remains largely unknown. This study sought to investigate the basal ganglia circuit structural and functional imaging differences in BN patients with different severity. Methods: Based on the MRI data acquired from 34 mild BN patients, 35 moderate-to-extreme BN patients and 35 healthy controls (HCs), differences in gray matter volume (GMV), fractional anisotropy, fractional amplitude of low-frequency fluctuation (fALFF), and seed-based functional connectivity (FC) of basal ganglia circuit (including the caudate, globus pallidus, nucleus accumbens and putamen) were compared across the three groups. Results: Compared to HCs, the mild patients only exhibited decreased fALFF in the left ventromedial putamen and increased FC between the nucleus accumbens and orbitofrontal cortex, without any structural imaging alterations. Whereas, the moderate-to-extreme patients exhibited significant basal ganglia imaging alterations, characterized by widespread higher FC between basal ganglia regions and several frontal-parietotemporal regions, and disrupted white matter integrity. Based on receiver operating characteristic curves, we discovered that seed-based FC had acceptable discriminatory values in classifying BN patients into mild or moderate-to-extreme groups. Conclusion: This study reveals that basal ganglia circuit imaging alterations in BN patients become more pronounced with increasing disease severity, suggesting a crucial role of basal ganglia circuit in the progression of BN. Functional network reorganization between basal ganglia and other regions may serve as a potential risk imaging marker for BN progression.