Research on characteristics of resting-state functional connectivity strengths in patients with amnestic mild cognitive impairment

Abstract

Objective To explore a new index for reflecting the topological information of brain functional networks in patients at high risk of Alzheimer disease using characteristics of resting-state functional connectivity strengths(FCS) in patients with amnestic mild cognitive impairment(aMCI). Methods Thirty- one aMCI patients and 42 age, gender and years of education matched normal controls were enrolled between September 2009 and April 2011 in this study. The resting-state functional MRI(rs-fMRI) data of all participants were acquired and preprocessed. Then the whole-brain functional connectivities were constructed for exploring the distribution characteristics of hub regions which had higher FCS values. Using two-samplet test to compare group differences in age, years of education and each neuropsychological assessment. In addition, using Chi-squared test to compare group differences in gender. Group differences in FCS values were analyzed by general linear model. Finally, correlation analyses were used to evaluate the relationships between the FCS values of the brain regions with group differences and behavioral scores in aMCI patients. Results The hub regions of the functional networks in the aMCI patients were mainly located in the association cortices such as the precuneuses, posterior cingulate cortices, medial prefrontal cortices, angular gyri, superior occipital gyri, fusiform gyri and lingual gyri. The distribution models in the aMCI patients were consistent with those in the normal controls. However, the FCS values of these brain regions were significantly lower in the aMCI patients than those in the normal controls. In comparison to the normal controls, the aMCI patients had significantly decreased FCS values in the bilateral fusiform gyri, lingual gyri, superior occipital gyri, left middle occipital gyrus and postcentral gyrus(the cluster was 389, 230, 187 and 107 voxels, respectively;P<0.05, respectively), and they had decreased trends of FCS values in the bilateral posterior cingulate cortices and right insulas. The correlation analysis with uncorrected conditions showed that the FCS values of the left postcentral gyri were correlatid with the clock drawing test (CDT) scores (r=0.436,P=0.026). Conclusions aMCI mainly attacks the hub regions of brain functional networks. The changes of functional connectivities in aMCI may reflect the early pathophysiologic alterations of AD. Key words: Cognition disorder; Magnetic resonance imaging; Neural network (computer)