Beta-Amyloid Deposition and the Aging Brain

Abstract

A central issue in cognitive neuroscience of aging research is pinpointing precise neural mechanisms that determine cognitive outcome in late adulthood as well as identifying early markers of less successful cognitive aging. One promising biomarker is beta amyloid (Aβ) deposition. Several new radiotracers have been developed that bind to fibrillar Aβ providing sensitive estimates of amyloid deposition in various brain regions. Aβ imaging has been primarily used to study patients with Alzheimer's Disease (AD) and individuals with Mild Cognitive Impairment (MCI); however, there is now building data on Aβ deposition in healthy controls that suggest at least 20% and perhaps as much as a third of healthy older adults show significant deposition. Considerable evidence suggests amyloid deposition precedes declines in cognition and may be the initiator in a cascade of events that indirectly leads to age-related cognitive decline. We review studies of Aβ deposition imaging in AD, MCI, and normal adults, its cognitive consequences, and the role of genetic risk and cognitive reserve. KeywordsAging; Beta-amyloid; Brain; Cognitive reserve; fMRI; PET Normal aging is associated with measurable declines in neural and cognitive systems. There is a wealth of literature documenting age-related declines in many aspects of cognitive behavior, including decreased speed of information processing, working memory capacity, and long-term memory function. At the same time, knowledge structures are relatively preserved with age (Ghisletta and Lindenberger 2003;Hedden and Gabrieli 2004;Park et al. 2002). Recently, significant advances have been made in our understanding of the structure and function of the aging brain utilizing new neuroimaging technologies (see Park and ReuterLorenz 2009;Park and Goh 2009;Raz and Kennedy 2009; Raz and Rodrigue 2006 for reviews). At present, a central issue in cognitive neuroscience of aging research is pinpointing the precise neural mechanisms that determine cognitive outcome in late adulthood as well as identifying markers of less successful cognitive aging as early in life as possible. Predicting successful vs. pathological aging trajectories requires early identification of sensitive behavioral or neural markers prior to actual neural pathology and cognitive decline. One such promising biomarker that has received recent attention is beta amyloid (Aβ), a protein that is deposited on the brain in some individuals as they age.© Springer Science + Business Media, LLC 2009 Correspondence to: Denise C. Park, denise@utdallas.edu. Disclosures The authors have no financial disclosures to report. NIH Public Access Author ManuscriptNeuropsychol Rev. Author manuscript; available in PMC 2010 December 1. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptSignificant amyloid deposition is a characteristic feature of all patients with Alzheimer's disease (AD). However, it is also present in many normal adults; it is observed in individuals with Mild Cognitive Impairment (MCI) at a leve...

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