title: Positron emission tomography and neuropathologic estimates of fibrillar amyloid-β in a patient with Down syndrome and Alzheimer disease.
abstract: BACKGROUND
  Down syndrome appears to be associated with a virtually certain risk of fibrillar amyloid-β (Aβ) pathology by the age of 40 and a very high risk of dementia at older ages. The positron emission tomography (PET) ligand florbetapir F18 has been shown to characterize fibrillar Aβ in the living human brain and to provide a close correlation with subsequent Aβ neuropathology in individuals proximate to and after the end of life. The extent to which the most frequently used PET ligands can be used to detect fibrillar Aβ in patients with Down syndrome remains to be determined.
  
  
  OBJECTIVE
  To characterize PET estimates of fibrillar Aβ burden in a Down syndrome patient very close to the end of life and to compare them with neuropathologic assessment made after his death. Design/
  
  
  METHODS
  With the family's informed consent, florbetapir PET was used to study a 55-year-old Down syndrome patient with Alzheimer disease near the end of life; his brain was donated for neuropathologic assessment when he died 14 days later. Visual ratings of cerebral florbetapir uptake were performed by trained readers who were masked to the patient's diagnosis as part of a larger study, and an automated algorithm was used to characterize regional-to-cerebellar standard uptake value ratios in 6 cerebral regions of interest. Neuropathologic assessments were performed masked to the patient's diagnosis or PET measurements.
  
  
  RESULTS
  Visual ratings and automated analyses of the PET image revealed a heavy fibrillar Aβ burden in cortical, striatal, and thalamic regions, similar to that reported for patients with late-onset Alzheimer disease. This matched neuropathologic findings of frequent neuritic and diffuse plaques, as well as frequent amyloid angiopathy, except for neuropathologically demonstrated frequent cerebellar diffuse plaques and amyloid angiopathy that were not detected by the PET scan.
  
  
  CONCLUSIONS
  Florbetapir PET can be used to detect increased cerebral-to-cerebellar fibrillar Aβ burden in a Down syndrome patient with Alzheimer disease, even in the presence of frequent amyloid angiopathy and diffuse plaques in the cerebellum. Additional studies are needed to determine the extent to which PET could be used to detect and to track fibrillar Aβ and to evaluate investigational Aβ-modifying treatments in the presymptomatic and symptomatic stages of Alzheimer disease.
authors.affiliation: The Cleo Roberts Center for Clinical Research, Banner Sun Health Research Institute, 101515 W Santa Fe Dr, Sun City, AZ 85351, USA. marwan.sabbagh@bannerhealth.com
authors.forename: Marwan N
authors.initials: MN
authors.lastname: Sabbagh
authors.forename: Adam
authors.initials: A
authors.lastname: Fleisher
authors.forename: Kewei
authors.initials: K
authors.lastname: Chen
authors.forename: Joseph
authors.initials: J
authors.lastname: Rogers
authors.forename: Camryn
authors.initials: C
authors.lastname: Berk
authors.forename: Eric
authors.initials: E
authors.lastname: Reiman
authors.forename: Michael
authors.initials: M
authors.lastname: Pontecorvo
authors.forename: Mark
authors.initials: M
authors.lastname: Mintun
authors.forename: Daniel
authors.initials: D
authors.lastname: Skovronsky
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Jacobson
authors.forename: Lucia I
authors.initials: LI
authors.lastname: Sue
authors.forename: Carolyn
authors.initials: C
authors.lastname: Liebsack
authors.forename: Albert S
authors.initials: AS
authors.lastname: Charney
authors.forename: Lauren
authors.initials: L
authors.lastname: Cole
authors.forename: Christine
authors.initials: C
authors.lastname: Belden
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Beach
mesh_terms: D000544:Alzheimer Disease / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D016229:Amyloid beta-Peptides; D004314:Down Syndrome / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D017809:Fatal Outcome; D006801:Humans; D008297:Male; D008875:Middle Aged; D058225:Plaque, Amyloid / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D049268:Positron-Emission Tomography
chemical_list: D016229:Amyloid beta-Peptides
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