Posterior cingulate cortex and global cerebral directed functional connectivity in patients with mild cognitive impairment and Alzheimer’s disease

Abstract

Objective To investigate the differences of directed functional connectivity between patients with mild cognitive impairment(MCI)/Alzheimer’s disease(AD) and healthy older. Methods Patients being treated at Zhejiang provincial people’s hospital from July 2012 to June 2014 were selected and divided into three groups, including Alzheimer disease group (n=32), the mild cognitive impairment group (n=26). Fitty-eight healthy olders over the same period were selected as normal control (NC) group (n=58). Based on resting state cerebral function imaging, the technique of independent component analysis (ICA) was applied to identify the brain hub nodes and Granger causality analysis (GCA) was used to explore the directed functional connectivity between PCC and the brain. One-way analysis of variance was used to screen out different directed functional connectivity among three groups, then regions of interest were analyzed in encephalic region, and original data analysis of resting state brain function was performed by DPARSF and REST,t-test was used to screen out the different directed functional connectivity between two groups. Results Almost all the abnormal directed functional connectivity were confirmed to be single-directed. Compared with NC group, the abnormal directed functional connectivity in AD group was in the other regions of the brain out of DMN. Compared with MCI, the most abnormal nodes in AD group were included in DMN, the abnormal direction between PCC and other regions of the brain was asymmetry. Most of the abnormal directions occur in the left hemisphere rather than the right. Conclusion As an important hub node in DMN, PCC plays an important role in the progress of AD. The abnormal directed functional connectivity in PCC further confirmed that abnormal signal transduction is directional, and the asymmetry of abnormal connectivity between the left and right is related to the usage of dominant hemisphere. Key words: Cognitive impairment; Alzheimer disease; Gyrus cinguli; Cerebrum; Signal transduction