title: Frequency-specific alterations of large-scale functional brain networks in patients with Alzheimer's disease.
abstract: BACKGROUND
  Previous studies have indicated that the cognitive deficits in patients with Alzheimer's disease (AD) may be due to topological deteriorations of the brain network. However, whether the selection of a specific frequency band could impact the topological properties is still not clear. Our hypothesis is that the topological properties of AD patients are also frequency-specific.
  
  
  METHODS
  Resting state functional magnetic resonance imaging data from 10 right-handed moderate AD patients (mean age: 64.3 years; mean mini mental state examination [MMSE]: 18.0) and 10 age and gender-matched healthy controls (mean age: 63.6 years; mean MMSE: 28.2) were enrolled in this study. The global efficiency, the clustering coefficient (CC), the characteristic path length (CpL), and "small-world" property were calculated in a wide range of thresholds and averaged within each group, at three different frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz, and 0.11-0.25 Hz).
  
  
  RESULTS
  At lower-frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz), the global efficiency, the CC and the "small-world" properties of AD patients decreased compared to controls. While at higher-frequency bands (0.11-0.25 Hz), the CpL was much longer, and the "small-world" property was disrupted in AD, particularly at a higher threshold. The topological properties changed with different frequency bands, suggesting the existence of disrupted global and local functional organization associated with AD.
  
  
  CONCLUSIONS
  This study demonstrates that the topological alterations of large-scale functional brain networks in AD patients are frequency dependent, thus providing fundamental support for optimal frequency selection in future related research.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Qin
authors.forename: Ya-Peng
authors.initials: YP
authors.lastname: Li
authors.forename: Shun
authors.initials: S
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiong
authors.forename: Lin-Ying
authors.initials: LY
authors.lastname: Guo
authors.forename: Shi-Qi
authors.initials: SQ
authors.lastname: Yang
authors.forename: Yi-Hao
authors.initials: YH
authors.lastname: Yao
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Wen-Zhen
authors.initials: WZ
authors.lastname: Zhu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis*; D001921:Brain / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged