Premium
F4‐01‐01: Amyloid imaging in at risk cognitively normal individuals and patients with subjective cognitive impairment
Author(s) -
Chetelat Gaël,
Desgranges Béatrice,
Eustache Francis,
Perrotin Audrey,
la Sayette Vincent,
Fouquet Marine,
Villain Nicolas
Publication year - 2012
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2012.05.1625
Subject(s) - atrophy , dementia , cognition , psychology , asymptomatic , pittsburgh compound b , neuroimaging , cognitive decline , disease , neuroscience , hippocampal formation , cognitive impairment , medicine , audiology
Background: A substantial proportion (20-30%) of cognitively normal elderly have significant Ab deposition in the brain as evidenced using PET amyloid imaging (especially PiB-PET). Moreover, several risk factors for AD have been shown to be associated with increased level of Ab deposition. It is still unknown however whether or not an Ab-positive PET scan reflects a predisposition to Alzheimer’s Disease (AD). Methods: The present talk reviews recent literature on amyloid imaging and the relationships of Ab with cognition and atrophy in cognitively normal elderly and at-risk populations. This includes ApoE4 carriers, individuals with a positive family history or with subjective cognitive impairment (SCI), and mutation carriers of a gene known to cause dominantly inherited AD (DHAD). Results: Several studies suggest that an Ab-positive PET-scan in cognitively normal elderly is associated with hippocampal atrophy and episodic memory deficits. Negative findings have been reported as well, suggesting that the relationship is probably weak or indirect. High Ab has also been associated with greater rates of atrophy and cognitive decline. Moreover, within normal elderly, APOE-ε4 carriers or those with a positive family history of AD have increased cortical Ab deposition. Asymptomatic DHAD mutation carriers seem to show a different uptake pattern (with higher striatal binding), while the effect of SCI is less consistent. Brain reserve and exercise probablymodulate the degree of Ab deposition and its relationships with cognition and atrophy. Conclusions: There is strong evidence that, at a group level, cognitively normal elderly with high level of cerebral Ab-deposition have increased risk for AD and worse prognosis compared to a group of Ab-negative individuals. However, we can’t say whether all individuals with a PiB-positive scan will eventually develop AD dementia, and still more important, when they would. A PiB scan provides reliable information about the presence of Ab in the brain, not about the presence of AD. The relative risk associated with a PiB-positive PET scan still remains to be determined. This raises ethical issues with regards to the use of amyloid imaging in clinic as well as the information released to participants in amyloid imaging research protocols.