title: Resting state functional connectivity is associated with cognitive dysfunction in non-demented people with Parkinson's disease.
abstract: BACKGROUND
  Parkinson's disease (PD) can result in cognitive impairment. Executive dysfunction often appears early, followed by more widespread deficits later in the course of the disease. Disruption of parallel basal ganglia thalamo-cortical loops that subserve motor and cognitive function has been described in PD. However, there is emerging evidence that the default mode network, a cortical network that is active at rest with reduced activation during task performance, may also play a role in disease related cognitive decline.
  
  
  OBJECTIVE
  To determine the relative contribution of the executive control and default mode networks to parkinsonian executive dysfunction in medicated non-demented patients.
  
  
  METHODS
  We used BOLD fMRI to measure resting state functional connectivity in the executive control and default mode (DM) networks, and examined switching, processing speed, working memory/attention and motor performance in 14 medicated non-demented PD participants and 20 controls.
  
  
  RESULTS
  Performance on neuropsychological measures was similar across groups. Functional connectivity was not different across disease conditions in the executive control network. DMN functional connectivity was decreased in the PD group, specifically between posterior cingulate, medial prefrontal, and inferior parietal nodes. Greater DMN functional connectivity was associated with faster processing speed in the PD group.
  
  
  CONCLUSIONS
  The continuous relationship between DMN disconnection and executive task performance indicates a possible biological contributor to parkinsonian cognitive deficits. The dynamics of executive control network change may be different than that of the DMN, suggesting less sensitivity to early cognitive deficits.
authors.affiliation: Overton Brooks VA Medical Center, Shreveport LA, USA LSU Health Sciences Center, Shreveport LA, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Disbrow
authors.affiliation: Center for Neuroscience, UC Davis, Davis CA, USA.
authors.forename: O
authors.initials: O
authors.lastname: Carmichael
authors.affiliation: Center for Neuroscience, UC Davis, Davis CA, USA.
authors.forename: J
authors.initials: J
authors.lastname: He
authors.affiliation: Department of Psychology, William Jessup University, Rocklin, CA, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Lanni
authors.affiliation: Center for Neuroscience, UC Davis, Davis CA, USA VA Northern California Health Care System, Martinez CA, USA.
authors.forename: E M
authors.initials: EM
authors.lastname: Dressler
authors.affiliation: Department of Neurology, UC Davis, Sacramento CA, USA.
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Neurology, UC Davis, Sacramento CA, USA.
authors.forename: N
authors.initials: N
authors.lastname: Malhado-Chang
authors.affiliation: Department of Neurology, UC Davis, Sacramento CA, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Sigvardt
mesh_terms: D000368:Aged; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D003072:Cognition Disorders / Q000150:complications / Q000503:physiopathology; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology*; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D012146:Rest
keywords: Executive control network; default mode network; fMRI; switching