title: Default-mode network connectivity in cognitively unimpaired patients with Parkinson disease.
abstract: OBJECTIVE
  Using resting-state (RS) fMRI, we investigated the functional integrity of the default-mode network (DMN) in cognitively unimpaired patients with Parkinson disease (PD).
  
  
  METHODS
  RS fMRI at 3 T was collected in 16 cognitively unimpaired patients with PD and 16 age- and gender-matched healthy controls. Single-subject and group-level independent component analysis was used to investigate differences in functional connectivity within the DMN in patients with PD and healthy controls. Statistical analysis was performed using BrainVoyager QX. In addition, we used voxel-based morphometry to test whether between-group differences in RS functional connectivity were related to structural abnormalities.
  
  
  RESULTS
  Patients with PD compared with controls showed a decreased functional connectivity of the right medial temporal lobe and bilateral inferior parietal cortex within the DMN. Although patients with PD were cognitively unimpaired, the decreased DMN connectivity significantly correlated with cognitive parameters but not with disease duration, motor impairment, or levodopa therapy. The analysis of regional volume differences did not reveal any differences in local gray matter between patients and controls.
  
  
  CONCLUSIONS
  Our findings revealed a functional disruption of the DMN in cognitively unimpaired patients with PD, in the absence of significant structural differences between patients and controls. We hypothesize that a dysfunction of the DMN connectivity may have a role in the development of cognitive decline in PD.
authors.affiliation: Department of Neurology, Second University of Naples, Naples, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Tessitore
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Esposito
authors.forename: Carmine
authors.initials: C
authors.lastname: Vitale
authors.forename: Gabriella
authors.initials: G
authors.lastname: Santangelo
authors.forename: Marianna
authors.initials: M
authors.lastname: Amboni
authors.forename: Antonio
authors.initials: A
authors.lastname: Russo
authors.forename: Daniele
authors.initials: D
authors.lastname: Corbo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cirillo
authors.forename: Paolo
authors.initials: P
authors.lastname: Barone
authors.forename: Gioacchino
authors.initials: G
authors.lastname: Tedeschi
mesh_terms: D000368:Aged; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology*; D009434:Neural Pathways / Q000503:physiopathology; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000503:physiopathology* / Q000523:psychology