title: Directed Functional Connectivity of Posterior Cingulate Cortex and Whole Brain in Alzheimer's Disease and Mild Cognitive Impairment.
abstract: Impaired functional connectivity in the default mode network (DMN) is supposedly involved in Alzheimer's disease (AD) progression. The posterior cingulate cortex (PCC) might be an imaging marker for monitoring AD progression.
  
  
  
  To investigate the alterations in the directed functional connectivity between the PCC and whole brain in patients with AD, patients with mild cognitive impairment (MCI), and healthy controls.
  
  
  
  A total of 116 enrolled participants were divided into three groups: AD (n=32), MCI (n=26), and controls (n=58). Using resting-state functional magnetic resonance imaging (rs-fMRI), the directed functional connectivity was studied using Granger causality analysis (GCA).
  
  
  
  Almost all of the directed functional connections with significant differences were unidirectional. Compared with the NC group, the AD group showed enhanced directed connectivity from the whole brain to the PCC mainly for regions outside the DMN, and reduced connectivity from the PCC to the whole brain mainly for regions inside the DMN. Compared with the NC group, the MCI group showed enhanced directed connectivity from the PCC to the whole brain for the bilateral precuneus and postcentralgyrus, and reduced connectivity from the whole brain to the PCC for regions outside the DMN. Compared with the MCI group, the abnormal directed connectivity in the AD group was predominantly in the left hemisphere, possibly suggesting asymmetric characteristics.
  
  
  
  In patients with AD, the PCC in the DMN shows disorders in receiving and transmitting information, and these abnormalities are directional.
authors.affiliation: Department of Psychiatric, Zhejiang Provincial People's Hospital, Hangzhou 310014, Zhejiang, China.
authors.forename: Enyan
authors.initials: E
authors.lastname: Yu
authors.affiliation: Department of Psychiatric, Zhejiang Provincial People's Hospital, Hangzhou 310014, Zhejiang, China.
authors.forename: Zhengluan
authors.initials: Z
authors.lastname: Liao
authors.affiliation: Department of Radiology, Zhejiang Provincial People's Hospital, Hangzhou 310014, Zhejiang, China.
authors.forename: Dewang
authors.initials: D
authors.lastname: Mao
authors.affiliation: Department of Radiology, Zhejiang Provincial People's Hospital, Hangzhou 310014, Zhejiang, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou 311121, Zhejiang, China.
authors.forename: Gongjun
authors.initials: G
authors.lastname: Ji
authors.affiliation: Department of Radiology, Zhejiang Provincial People's Hospital, Hangzhou 310014, Zhejiang, China.
authors.forename: Yumei
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Radiology, Zhejiang Provincial People's Hospital, Hangzhou 310014, Zhejiang, China.
authors.forename: Zhongxiang
authors.initials: Z
authors.lastname: Ding
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000473:pathology*; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology*; D060825:Cognitive Dysfunction / Q000473:pathology*; D005260:Female; D006179:Gyrus Cinguli / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D008959:Models, Neurological; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000473:pathology*; D010100:Oxygen / Q000097:blood; D012189:Retrospective Studies; D018709:Statistics, Nonparametric
chemical_list: D010100:Oxygen
keywords: Alzheimer's disease; Mild cognitive impairment; default mode network; directed functional connectivity; posterior cingulate cortex; resting-state functional brain imaging