title: Pattern of Reduced Functional Connectivity and Structural Abnormalities in Parkinson's Disease: An Exploratory Study.
abstract: BACKGROUND
  MRI brain changes in Parkinson's disease (PD) are controversial.
  
  
  OBJECTIVE
  We aimed to describe structural and functional changes in PD.
  
  
  METHODS
  Sixty-six patients with PD (57.94 ± 10.25 years) diagnosed according to the UK Brain Bank criteria were included. We performed a whole brain analysis using voxel-based morphometry (VBM-SPM 8 software), cortical thickness (CT) using CIVET, and resting-state fMRI using the Neuroimaging Analysis Kit software to compare patients and controls. For VBM and CT we classified subjects into three groups according to disease severity: mild PD [Hoehn and Yahr scale (HY) 1-1.5], moderate PD (HY 2-2.5), and severe PD (HY 3-5).
  
  
  RESULTS
  We observed gray matter atrophy in the insula and inferior frontal gyrus in the moderate PD and in the insula, frontal gyrus, putamen, cingulated, and paracingulate gyri in the severe groups. In the CT analysis, in mild PD, cortical thinning was restricted to the superior temporal gyrus, gyrus rectus, and olfactory cortex; in the moderate group, the postcentral gyrus, supplementary motor area, and inferior frontal gyrus were also affected; in the severe PD, areas such as the precentral and postentral gyrus, temporal pole, fusiform, and occipital gyrus had reduced cortical thinning. We observed altered connectivity at the default mode, visual, sensorimotor, and cerebellar networks.
  
  
  CONCLUSIONS
  Subjects with mild symptoms already have cortical involvement; however, further cerebral involvement seems to follow Braak's proposed mechanism. Similar regions are affected both structurally and functionally. We believe the combination of different MRI techniques may be useful in evaluating progressive brain involvement and they may eventually be used as surrogate markers of disease progression.
authors.affiliation: Department of Neurology, University of Campinas, Campinas, Brazil; Laboratory of Neuroimaging, University of Campinas, Campinas, Brazil; Montreal Neurological Institute, Brain Imaging Center, McGill University, Montreal, QC, Canada.
authors.forename: Rachel Paes
authors.initials: RP
authors.lastname: Guimarães
authors.affiliation: Laboratory of Neuroimaging, University of Campinas , Campinas , Brazil.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Arci Santos
authors.affiliation: Montreal Neurological Institute, Brain Imaging Center, McGill University , Montreal, QC , Canada.
authors.forename: Alain
authors.initials: A
authors.lastname: Dagher
authors.affiliation: Department of Neurology, University of Campinas , Campinas , Brazil.
authors.forename: Lidiane Soares
authors.initials: LS
authors.lastname: Campos
authors.affiliation: Department of Neurology, University of Campinas , Campinas , Brazil.
authors.forename: Paula
authors.initials: P
authors.lastname: Azevedo
authors.affiliation: Department of Neurology, University of Campinas , Campinas , Brazil.
authors.forename: Luiza Gonzaga
authors.initials: LG
authors.lastname: Piovesana
authors.affiliation: Laboratory of Neuroimaging, University of Campinas , Campinas , Brazil.
authors.forename: Brunno Machado
authors.initials: BM
authors.lastname: De Campos
authors.affiliation: Montreal Neurological Institute, Brain Imaging Center, McGill University , Montreal, QC , Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Larcher
authors.affiliation: Montreal Neurological Institute, Brain Imaging Center, McGill University , Montreal, QC , Canada.
authors.forename: Yashar
authors.initials: Y
authors.lastname: Zeighami
authors.affiliation: Department of Radiology, University of Campinas , Campinas , Brazil.
authors.forename: Augusto C
authors.initials: AC
authors.lastname: Scarparo Amato-Filho
authors.affiliation: Department of Neurology, University of Campinas, Campinas, Brazil; Laboratory of Neuroimaging, University of Campinas, Campinas, Brazil.
authors.forename: Fernando
authors.initials: F
authors.lastname: Cendes
authors.affiliation: Department of Neurology, University of Campinas, Campinas, Brazil; Laboratory of Neuroimaging, University of Campinas, Campinas, Brazil.
authors.forename: Anelyssa Cysne Frota
authors.initials: AC
authors.lastname: D'Abreu
keywords: Parkinson’s disease; cortical thickness; functional MRI; neuroimaging; voxel-based morphometry