Objective: To investigate the safety, acceptability, and feasibility of positron emission tomography (PET) using carbon 11-labeled Pittsburgh Compound B ([(11)C]PiB) to measure cerebral β-amyloid in adults with Down syndrome (DS) and to explore if the technique differentiates between participants with and without Alzheimer disease (AD).
Design: Proof-of-principle case-controlled study of a nonrandomly selected cohort of participants with DS (with or without AD) compared within group and with healthy controls without DS. All had dynamic [(11)C]PiB PET and magnetic resonance imaging. Carbon 11-labeled PiB binding in the regions of interest associated with AD was quantitatively analyzed.
Setting: Wolfson Brain Imaging Centre, Cambridge, England.
Participants: Nine with DS (aged 25-64 years), of whom 5 had a diagnosis of AD, and 14 healthy controls without DS (aged 33-69 years).
Main outcome measure: Positive [(11)C]PiB binding in regions of interest.
Results: The scanning process was feasible and acceptable with no adverse events or safety concerns. Maps and regional values of nondisplaceable binding potential were produced using the reference tissue-input Logan plot, with the cerebellum used as the reference tissue. When compared with the healthy control group without DS, only participants with DS older than 45 years had significant [(11)C]PiB binding in regions of interest usually associated with AD, whether or not they had clinical evidence of dementia.
Conclusions: Dynamic [(11)C]PiB PET can be used successfully to measure cerebral β-amyloid deposition in DS. A clinical diagnosis of AD and age appear to be predictors of [(11)C]PiB binding in regions of interest, but given the small numbers, we cannot generalize the results.