title: Characterization of brain blood flow and the amplitude of low-frequency fluctuations in major depressive disorder: A multimodal meta-analysis.
abstract: In healthy subjects, there is an association between amplitude of low-frequency fluctuations (ALFF) and regional cerebral blood flow (rCBF). To date, no published meta-analysis has investigated changes in the regional ALFF in medication-free depressed patients.
  
  
  
  In this study, we aimed to explore whether resting-state rCBF and ALFF changes co-occur in the depressed brain without the potential confound of medication. Using signed differential mapping (SDM), we conducted two meta-analyses, one of rCBF studies and one of ALFF studies, involving medication-free patients with major depressive disorder (MDD). In addition, we conducted a multimodal meta-analysis to identify brain regions that showed abnormalities in both rCBF and ALFF.
  
  
  
  A total of 16 studies were included in this series. We identified abnormalities in resting-state rCBF and ALFF in the left insula in medication-free MDD patients compared with healthy controls (HC). In addition, we observed altered resting-state rCBF in the limbic-subcortical-cortical circuit and altered ALFF in the default mode network (DMN) and some motor-related brain regions.
  
  
  
  The analysis techniques, patient characteristics and clinical variables of the included studies were heterogeneous.
  
  
  
  The conjoint alterations in ALFF and rCBF in the left insula may represent core neuropathological changes in medication-free patients with MDD and merit further studying.
authors.affiliation: Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Li
authors.affiliation: Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.
authors.forename: Ziqi
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.
authors.forename: Min
authors.initials: M
authors.lastname: Wu
authors.affiliation: Laboratory of Stem Cell Biology, West China Hospital of Sichuan University, Chengdu, Sichuan, China. Electronic address: hyzhu_hmrrc@126.com.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Laboratory of Stem Cell Biology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Gu
authors.affiliation: Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.
authors.forename: Youjin
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Psychiatry, West China Hospital of Sichuan University, Chengdu, Sichuan, China.
authors.forename: Weihong
authors.initials: W
authors.lastname: Kuang
authors.affiliation: Department of Oncology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Bi
authors.affiliation: Magnetic Resonance and Image Analysis Research Centre and Institute of Ageing and Chronic Disease, University of Liverpool, United Kingdom.
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Kemp
authors.affiliation: Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China; Department of Psychiatry, West China Hospital of Sichuan University, Chengdu, Sichuan, China; Department of Psychology, School of Public Administration, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Qiyong
authors.initials: Q
authors.lastname: Gong
mesh_terms: D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003865:Major Depressive Disorder / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods
keywords: Amplitude of low-frequency fluctuations; Insula; Major depressive disorder; Multimodal analysis; Regional cerebral blood flow; fMRI