Functional Network Alterations in Patients With Amnestic Mild Cognitive Impairment Characterized Using Functional Near-Infrared Spectroscopy.

Amnestic mild cognitive impairment (aMCI) is conceptualized as a cognitive disorder characterized by memory deficits. Patients with aMCI are treated as prodromal stage of Alzheimer's disease (AD) and have an increased likelihood of developing into AD. The investigation of aMCI is therefore fundamental to the early detection and intervention of AD. Growing evidence has shown that functional network alterations induced by cognition impairment can be captured by advanced neuroimaging techniques. In this study, functional near-infrared spectroscopy (fNIRS), an affordable, robust and portable neuroimaging modality, was employed to characterize the functional network in aMCI patients. FNIRS data were collected from 16 healthy controls and 16 aMCI patients using a digits verbal span task. Functional networks were constructed from temporal hemodynamic response signals. Graph-based indices were then calculated from the constructed brain networks to assess global and regional differences between the groups. Results suggested that brain networks in aMCI patients were characterized with higher integration as well as higher segregation compared to healthy controls. In addition, major regions of interest (ROIs) within frontal, temporal, precentral and parietal areas were identified to be associated with cognition impairment. Our findings validate the feasibility of utilizing fNIRS as a portable and reliable tool for the investigation of abnormal network alterations in patients with cognition decline.