title: Altered functional connectivity in early Alzheimer's disease: a resting-state fMRI study.
abstract: Previous studies have led to the proposal that patients with Alzheimer's disease (AD) may have disturbed functional connectivity between different brain regions. Furthermore, recent resting-state functional magnetic resonance imaging (fMRI) studies have also shown that low-frequency (<0.08 Hz) fluctuations (LFF) of the blood oxygenation level-dependent signals were abnormal in several brain areas of AD patients. However, few studies have investigated disturbed LFF connectivity in AD patients. By using resting-state fMRI, this study sought to investigate the abnormal functional connectivities throughout the entire brain of early AD patients, and analyze the global distribution of these abnormalities. For this purpose, the authors divided the whole brain into 116 regions and identified abnormal connectivities by comparing the correlation coefficients of each pair. Compared with healthy controls, AD patients had decreased positive correlations between the prefrontal and parietal lobes, but increased positive correlations within the prefrontal lobe, parietal lobe, and occipital lobe. The AD patients also had decreased negative correlations (closer to zero) between two intrinsically anti-correlated networks that had previously been found in the resting brain. By using resting-state fMRI, our results supported previous studies that have reported an anterior-posterior disconnection phenomenon and increased within-lobe functional connectivity in AD patients. In addition, the results also suggest that AD may disturb the correlation/anti-correlation effect in the two intrinsically anti-correlated networks.
authors.affiliation: National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, People's Republic of China.
authors.forename: Kun
authors.initials: K
authors.lastname: Wang
authors.forename: Meng
authors.initials: M
authors.lastname: Liang
authors.forename: Liang
authors.initials: L
authors.lastname: Wang
authors.forename: Lixia
authors.initials: L
authors.lastname: Tian
authors.forename: Xinqing
authors.initials: X
authors.lastname: Zhang
authors.forename: Kuncheng
authors.initials: K
authors.lastname: Li
authors.forename: Tianzi
authors.initials: T
authors.lastname: Jiang
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis / Q000503:physiopathology*; D001921:Brain / Q000033:anatomy & histology / Q000503:physiopathology*; D003072:Cognition Disorders / Q000175:diagnosis / Q000503:physiopathology; D018450:Disease Progression; D042241:Early Diagnosis; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000033:anatomy & histology / Q000503:physiopathology*; D009434:Neural Pathways / Q000033:anatomy & histology / Q000503:physiopathology*; D009483:Neuropsychological Tests; D009778:Occipital Lobe / Q000033:anatomy & histology / Q000503:physiopathology; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000503:physiopathology; D011237:Predictive Value of Tests; D017397:Prefrontal Cortex / Q000033:anatomy & histology / Q000503:physiopathology; D011379:Prognosis