Reduced efficiency of functional brain network underlying intellectual decline in patients with low-grade glioma.

Low-grade glioma (LGG) patients are typically accompanied by varying degrees of intellectual impairments. However, the neural mechanisms underlying intellectual decline have not yet been well understood. The aim of this study is to investigate the relationship between possibly altered functional brain network properties and intellectual decline in LGG patients. Chinese revised Wechsler adult intelligence scale (WAIS-RC) was used to assess the intelligence of 21 LGG patients and 20 healthy controls, matched in age, gender and education. Resting-state functional magnetic resonance imaging (fMRI) was performed for all the subjects to analyze functional network characteristics with graph theory. The LGG patients showed significantly poor performance on intelligence test than controls (P<0.05). Compared with controls, the patients displayed disturbed small-world manner (increased characteristic path length L and normalized characteristic path length λ) and decreased global efficiency Eglob. Specially, we found that Eglob was positively correlated with intelligence quotient (IQ) test scores in LGG group. Furthermore, network hubs, which could significantly affect the network efficiency, were in the right insula and right posterior cingulate cortex in controls, while in the right thalamus and right posterior cingulate cortex in the patients. From the perspective of brain network, our results provided evidence of reduced global efficiency for poorer intellectual performance in LGG patients, which contributed to understanding the basis of intellectual impairments.