title: Parkinson's disease diffusion MRI is not affected by acute antiparkinsonian medication.
abstract: A prior longitudinal study demonstrates that free-water diffusion magnetic resonance imaging (dMRI) tracks progression in the substantia nigra (Ofori et al., 2015b). Here, we test the acute effects of antiparkinsonian medication on this established imaging progression marker for the first time.
  
  
  
  Fifteen PD patients underwent dMRI OFF and ON-medication one day apart. ON-medication, patients were tested approximately 45 min after their usual dose of antiparkinsonian medication. OFF-medication, patients were tested after not taking antiparkinsonian medication for > 12 h. OFF and ON-medication was counter-balanced across subjects. For dMRI, we computed free-water and free-water corrected fractional anisotropy (FAt) within the following regions: caudate, putamen, substantia nigra, and subthalamic nucleus.
  
  
  
  ON-medication significantly reduced parkinsonian motor symptoms compared with OFF-medication (p< 0.001). dMRI measures (free-water and FAt) were not different between the OFF and ON-medication conditions.
  
  
  
  Administration of an acute does of anti-parkinsonian medication in PD does not affect free-water and FAtin key nigrostriatal structures. Free-water and FAtbiomarkers reflect the chronic state of the nigrostriatal circuit, and therefore are potential viable biomarkers for disease-modifying therapeutic studies in PD.
authors.affiliation: Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
authors.forename: Jae Woo
authors.initials: JW
authors.lastname: Chung
authors.affiliation: Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
authors.forename: Roxana G
authors.initials: RG
authors.lastname: Burciu
authors.affiliation: Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Ofori
authors.affiliation: Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
authors.forename: Priyank
authors.initials: P
authors.lastname: Shukla
authors.affiliation: Department of Neurology and Center for Movement Disorders and Neurorestoration, University of Florida, Gainesville, FL, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Okun
authors.affiliation: Department of Neurology and Center for Movement Disorders and Neurorestoration, University of Florida, Gainesville, FL, USA.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Hess
authors.affiliation: Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA; Department of Neurology and Center for Movement Disorders and Neurorestoration, University of Florida, Gainesville, FL, USA; Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Vaillancourt
mesh_terms: D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use*; D001921:Brain / Q000000981:diagnostic imaging* / Q000187:drug effects*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D012720:Severity of Illness Index
chemical_list: D000978:Antiparkinson Agents
keywords: Antiparkinsonian medication; Free-water; Free-water corrected fractional anisotropy; Parkinson's disease; dMRI