Alterations of directional connectivity among resting-state networks in Alzheimer disease.
OBJECTIVE
AD has been documented as a kind of disconnection syndrome by functional neuroimaging studies. The primary focus of this study was to examine, with the use of resting-state fMRI, whether AD would impact connectivity among RSNs.


METHODS
Fourteen patients with AD and 16 NC were recruited and scanned by using resting-state fMRI. Group independent-component analysis and the BN learning approach were used, respectively, to separate the RSNs and construct the network-to-network connectivity patterns for each group. The convergence index for the special network DMN was measured.


RESULTS
Three of the 4 connections were significantly lower in AD compared with NC. Although numerically the AD group had more connections, none was statistically different from that in the NC group except for 1 increased connection from the DMN to the DAN. The convergence index for the DMN node was lower in AD than in NC.


CONCLUSIONS
Connections among cognitive networks in AD were more vulnerable to impairment than sensory networks. The DMN decreased its integration function for other RSNs but may also play a role in compensating for the disrupted connections in AD.
Center on Aging Psychology, Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China.
R
R
Li
X
X
Wu
K
K
Chen
A S
AS
Fleisher
E M
EM
Reiman
L
L
Yao
D000368:Aged; D000544:Alzheimer Disease / Q000503:physiopathology*; D001921:Brain / Q000502:physiology; D001931:Brain Mapping / Q000379:methods*; D063132:Connectome / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net; D012146:Rest / Q000502:physiology