title: Default mode network links to visual hallucinations: A comparison between Parkinson's disease and multiple system atrophy.
abstract: BACKGROUND
  Studying default mode network activity or connectivity in different parkinsonisms, with or without visual hallucinations, could highlight its roles in clinical phenotypes' expression. Multiple system atrophy is the archetype of parkinsonism without visual hallucinations, variably appearing instead in Parkinson's disease (PD). We aimed to evaluate default mode network functions in multiple system atrophy in comparison with PD.
  
  
  METHODS
  Functional magnetic resonance imaging evaluated default mode network activity and connectivity in 15 multiple system atrophy patients, 15 healthy controls, 15 early PD patients matched for disease duration, 30 severe PD patients (15 with and 15 without visual hallucinations), matched with multiple system atrophy for disease severity. Cortical thickness and neuropsychological evaluations were also performed.
  
  
  RESULTS
  Multiple system atrophy had reduced default mode network activity compared with controls and PD with hallucinations, and no differences with PD (early or severe) without hallucinations. In PD with visual hallucinations, activity and connectivity was preserved compared with controls and higher than in other groups. In early PD, connectivity was lower than in controls but higher than in multiple system atrophy and severe PD without hallucinations. Cortical thickness was reduced in severe PD, with and without hallucinations, and correlated only with disease duration. Higher anxiety scores were found in patients without hallucinations.
  
  
  CONCLUSIONS
  Default mode network activity and connectivity was higher in PD with visual hallucinations and reduced in multiple system atrophy and PD without visual hallucinations. Cortical thickness comparisons suggest that functional, rather than structural, changes underlie the activity and connectivity differences.
authors.affiliation: Department of Neuroscience, Imaging and Clinical Sciences, "G. d'Annunzio" University and Aging Research Centre, Ce.S.I., "G. d'Annunzio" University Foundation, Chieti, Italy.|ITAB, "G. d'Annunzio" University Foundation, Chieti, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Franciotti
authors.affiliation: Department of Neuroscience, Imaging and Clinical Sciences, "G. d'Annunzio" University and Aging Research Centre, Ce.S.I., "G. d'Annunzio" University Foundation, Chieti, Italy.|ITAB, "G. d'Annunzio" University Foundation, Chieti, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Delli Pizzi
authors.affiliation: Department of Neuroscience, Imaging and Clinical Sciences, "G. d'Annunzio" University and Aging Research Centre, Ce.S.I., "G. d'Annunzio" University Foundation, Chieti, Italy.
authors.forename: Bernardo
authors.initials: B
authors.lastname: Perfetti
authors.affiliation: Department of Neuroscience, Imaging and Clinical Sciences, "G. d'Annunzio" University and Aging Research Centre, Ce.S.I., "G. d'Annunzio" University Foundation, Chieti, Italy.|ITAB, "G. d'Annunzio" University Foundation, Chieti, Italy.
authors.forename: Armando
authors.initials: A
authors.lastname: Tartaro
authors.affiliation: Department of Neuroscience, Imaging and Clinical Sciences, "G. d'Annunzio" University and Aging Research Centre, Ce.S.I., "G. d'Annunzio" University Foundation, Chieti, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Bonanni
authors.affiliation: Department of Neuroscience, Imaging and Clinical Sciences, "G. d'Annunzio" University and Aging Research Centre, Ce.S.I., "G. d'Annunzio" University Foundation, Chieti, Italy.
authors.forename: Astrid
authors.initials: A
authors.lastname: Thomas
authors.affiliation: Department for Parkinson's Disease, "Fondazione Ospedale San Camillo", I.R.C.C.S, Venice, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Weis
authors.affiliation: Department for Parkinson's Disease, "Fondazione Ospedale San Camillo", I.R.C.C.S, Venice, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Biundo
authors.affiliation: Department for Parkinson's Disease, "Fondazione Ospedale San Camillo", I.R.C.C.S, Venice, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Antonini
authors.affiliation: Department of Neuroscience, Imaging and Clinical Sciences, "G. d'Annunzio" University and Aging Research Centre, Ce.S.I., "G. d'Annunzio" University Foundation, Chieti, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Onofrj
mesh_terms: D000368:Aged; D001921:Brain / Q000098:blood supply / Q000473:pathology*; D001931:Brain Mapping; D005260:Female; D006212:Hallucinations / Q000209:etiology* / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000150:complications*; D010100:Oxygen / Q000097:blood; D010300:Parkinson Disease / Q000150:complications*
chemical_list: D010100:Oxygen
keywords: Parkinson's disease; default mode network; multiple system atrophy; visual hallucinations