title: Aβ-amyloid deposition in patients with Parkinson disease at risk for development of dementia.
abstract: OBJECTIVE
  The aim of our study was to examine the relationship between corticostriatal Aβ-amyloid deposition and cognitive dysfunction in a cohort of patients with Parkinson disease (PD) at risk for dementia.
  
  
  METHODS
  This was a cross-sectional study of 40 patients with PD with mild cognitive impairment (MCI) or other known dementia risk factors. Subjects underwent dynamic Aβ-amyloid and vesicular monoamine transporter 2 PET imaging using [(11)C] Pittsburgh compound B (PiB) and [(11)C]dihydrotetrabenazine (DTBZ), respectively, and neuropsychological assessment. PiB and DTBZ PET data were analyzed using the Logan graphical method to determine cerebral PiB deposition relative to the cerebellar hemispheres and striatal DTBZ binding relative to occipital neocortex. Component z scores were calculated for individual cognitive domains (memory, visuospatial processing, working memory/attention, and executive function) and combined linearly for global estimation of cognition. Correlation of cognitive function and cortical PiB binding was investigated.
  
  
  RESULTS
  Elevated cerebral PiB binding at levels seen in patients with AD was infrequent (6 of 40 subjects). Mean cortical PiB binding in the entire cohort was 1.16 ± 0.16 (distribution volume ratio; range 0.96-1.78). A significant correlation was noted between cortical PiB binding and global composite cognitive function (r = -0.55, p < 0.005) as well as the Wechsler Adult Intelligence Scale score (r = -0.54, p = 0.0004).
  
  
  CONCLUSIONS
  Elevated cerebral Aβ-amyloid deposition at levels seen in Alzheimer disease is uncommon in subjects with PD at risk for dementia. In our sample, the prevalence of markedly elevated PiB binding was significantly lower than that found in prior studies of cognitively normal elderly individuals. Neocortical PiB binding correlated robustly with measures of cognitive impairment in our cohort.
authors.affiliation: Department of Radiology, Johns Hopkins School of Medicine, Baltimore, MD, USA. mpetrou@umich.edu
authors.forename: Myria
authors.initials: M
authors.lastname: Petrou
authors.forename: Nicolaas I
authors.initials: NI
authors.lastname: Bohnen
authors.forename: Martijn L T M
authors.initials: ML
authors.lastname: Müller
authors.forename: Robert A
authors.initials: RA
authors.lastname: Koeppe
authors.forename: Roger L
authors.initials: RL
authors.lastname: Albin
authors.forename: Kirk A
authors.initials: KA
authors.lastname: Frey
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D003072:Cognition Disorders / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism; D003430:Cross-Sectional Studies; D003704:Dementia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism; D058225:Plaque, Amyloid / Q000378:metabolism / Q000473:pathology*; D011877:Radionuclide Imaging
chemical_list: D016229:Amyloid beta-Peptides