title: Amyloid-Beta Positron Emission Tomography Imaging of Alzheimer's Pathology in Parkinson's Disease Dementia.
abstract: BACKGROUND
  Neuronal loss and α-synuclein (α-syn) pathology are diagnostic of PD in the appropriate clinical context. However, some PD patients have co-morbid Alzheimer's disease (AD) pathology on autopsy, including amyloid-β (Aβ) plaques and neurofibrillary tangles. Florbetapir(18F) is a PET ligand that detects Aβ pathology. We hypothesized that florbetapir(18F) imaging could detect Aβ pathology in Parkinson disease dementia (PDD) patients prior to death.
  
  
  OBJECTIVE
  To determine the utility of florbetapir(18F) PET imaging in detecting Aβ pathology in patients with autopsy-confirmed PDD.
  
  
  METHODS
  Five participants with PDD had florbetapir(18F) PET imaging prior to death as a part of a longitudinal research study of cognitive decline in PD. PET scans were evaluated by expert raters blinded to clinical and neuropathological information. At autopsy, all five participants underwent semi-quantitative assessments of regional Aβ and tau immunohistochemistry.
  
  
  RESULTS
  All participants met neuropathological criteria for PD. Two had both positive florbetapir(18F) scans and Aβ-positive plaques in multiple brain regions. Regional florbetapir(18F) binding correlated with regional semi-quantitative Aβ pathology in these cases. Three cases had negative florbetapir(18F) scans. Two of these had significant tau pathology without Aβ pathology, consistent with progressive supranuclear palsy (PSP) in one case and argyrophilic grain disease (AGD) in the other. The last case had a low level of AD neuropathological change.
  
  
  CONCLUSIONS
  Florbetapir(18F) Aβ imaging can detect the presence of Aβ neuropathology in patients with PDD. This imaging technique may aid the clinical evaluation of PDD patients to determine if cognitive decline is occurring in the setting of Aβ accumulation.
authors: Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-3339, USA; Center for Neurodegenerative Disease Research and Institute on Aging, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-3339, USA.
authors: Rizwan S
authors: RS
authors: Akhtar
authors: Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-3339, USA.
authors: Sharon X
authors: SX
authors: Xie
authors: Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-3339, USA; Department of Psychiatry, Perelman School of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-3339, USA.
authors: Laura
authors: L
authors: Brennan
authors: Avid Radiopharmaceuticals, Philadelphia, PA 19104, USA.
authors: Michael J
authors: MJ
authors: Pontecorvo
authors: Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-3339, USA.
authors: Howard I
authors: HI
authors: Hurtig
authors: Center for Neurodegenerative Disease Research and Institute on Aging, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-3339, USA; Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-3339, USA.
authors: John Q
authors: JQ
authors: Trojanowski
authors: Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-3339, USA; Department of Psychiatry, Perelman School of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-3339, USA.
authors: Daniel
authors: D
authors: Weintraub
authors: Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-3339, USA; Avid Radiopharmaceuticals, Philadelphia, PA 19104, USA.
authors: Andrew D
authors: AD
authors: Siderowf
keywords: Neuroimaging; autopsy; neurodegeneration; parkinsonism; tauopathy