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Behavioural Neurology
Volume 21 (2009), Issue 1-2, Pages 117-128
http://dx.doi.org/10.3233/BEN-2009-0232

Amyloid Imaging in Aging and Dementia: Testing the Amyloid Hypothesis In Vivo

G. D. Rabinovici1,2,3,4 and W. J. Jagust1,2,3,4

1Memory and Aging Center, University of California San Francisco, San Francisco, CA, USA
2Department of Neurology, University of California San Francisco, San Francisco, CA, USA
3Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, USA
4Lawrence Berkeley National Laboratory, Berkeley, CA, USA

Received 16 October 2009; Accepted 16 October 2009

Copyright © 2009 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Amyloid imaging represents a major advance in neuroscience, enabling the detection and quantification of pathologic protein aggregations in the brain. In this review we survey current amyloid imaging techniques, focusing on positron emission tomography (PET) with ^{11}carbon-labelled Pittsburgh Compound-B (11C-PIB), the most extensively studied and best validated tracer. PIB binds specifically to fibrillar beta-amyloid (Aβ) deposits, and is a sensitive marker for Aβ pathology in cognitively normal older individuals and patients with mild cognitive impairment (MCI) and Alzheimer’s disease (AD). PIB-PET provides us with a powerful tool to examine in vivo the relationship between amyloid deposition, clinical symptoms, and structural and functional brain changes in the continuum between normal aging and AD. Amyloid imaging studies support a model in which amyloid deposition is an early event on the path to dementia, beginning insidiously in cognitively normal individuals, and accompanied by subtle cognitive decline and functional and structural brain changes suggestive of incipient AD. As patients progress to dementia, clinical decline and neurodegeneration accelerate and proceed independently of amyloid accumulation. In the future, amyloid imaging is likely to supplement clinical evaluation in selecting patients for anti-amyloid therapies, while MRI and FDG-PET may be more appropriate markers of clinical progression.