Abnormal small-world architecture of top-down control networks in obsessive-compulsive disorder.
BACKGROUND
Obsessive-compulsive disorder (OCD) is a common neuropsychiatric disorder that is characterized by recurrent intrusive thoughts, ideas or images and repetitive ritualistic behaviours. Although focal structural and functional abnormalities in specific brain regions have been widely studied in populations with OCD, changes in the functional relations among them remain poorly understood. This study examined OCD-related alterations in functional connectivity patterns in the brain's top-down control network.


METHODS
We applied resting-state functional magnetic resonance imaging to investigate the correlation patterns of intrinsic or spontaneous blood oxygen level-dependent signal fluctuations in 18 patients with OCD and 16 healthy controls. The brain control networks were first constructed by thresholding temporal correlation matrices of 39 brain regions associated with top-down control and then analyzed using graph theory-based approaches.


RESULTS
Compared with healthy controls, the patients with OCD showed decreased functional connectivity in the posterior temporal regions and increased connectivity in various control regions such as the cingulate, precuneus, thalamus and cerebellum. Furthermore, the brain's control networks in the healthy controls showed small-world architecture (high clustering coefficients and short path lengths), suggesting an optimal balance between modularized and distributed information processing. In contrast, the patients with OCD showed significantly higher local clustering, implying abnormal functional organization in the control network. Further analysis revealed that the changes in network properties occurred in regions of increased functional connectivity strength in patients with OCD.


CONCLUSIONS
The patient group in the present study was heterogeneous in terms of symptom clusters, and most of the patients with OCD were medicated.


CONCLUSIONS
Our preliminary results suggest that the organizational patterns of intrinsic brain activity in the control networks are altered in patients with OCD and thus provide empirical evidence for aberrant functional connectivity in the large-scale brain systems in people with this disorder.
Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, China.
Tijiang
T
Zhang
Jinhui
J
Wang
Yanchun
Y
Yang
Qizhu
Q
Wu
Bin
B
Li
Long
L
Chen
Qiang
Q
Yue
Hehan
H
Tang
Chaogan
C
Yan
Su
S
Lui
Xiaoqi
X
Huang
Raymond C K
RC
Chan
Yufeng
Y
Zang
Yong
Y
He
Qiyong
Q
Gong
D000328:Adult; D001921:Brain / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008959:Models, Neurological; D009434:Neural Pathways / Q000503:physiopathology*; D009771:Obsessive-Compulsive Disorder / Q000503:physiopathology*