In studying the molecular changes leading to Alzheimer’s Disease (AD), researchers have focused on the presence of Amyloid plaques in the brain. Plaques are dense deposits of proteins found in the brains of AD patients but less frequently in healthy brains. A major constituent of these plaques is the protein beta-Amyloid. Dissecting the significance of these plaques has been a major focus for AD research.
Highlighting Health recently recapped a very informative press release of two Archives of Neurology articles(1,2).
The two articles studied these plaques in cognitively health patients who were then monitored over several years for the development of AD. Those patients who were later diagnosed with AD had previously shown indications of Amyloid plaques, years before the presence of AD symptoms.
However, the current finding rest at this statement:
Beta-amyloid deposition may be a risk factor for developing Alzheimer’s disease but its presence does not constitute a diagnostic finding.
That’s because some of the other patients who had plaques have still not developed AD, so it doesn’t appear to be 100%.
The articles are exciting because their the first to survey patients over a long period of time to monitor how early can signs of AD be detected.
How are Amyloid plaques detected in living patients?
The researchers took advantage of something called Pittsburg Compound B (PiB). This is a fluorescent form of a molecule called thioflavin T. PiB has the nice properties that it naturally passes into the brain and binds Amyloid, but is quickly washed out of the brain, leaving not lasting effects. While it is bound it can be detected by Positron Emission Tomography (PET)
Citations:
1: Morris JC, Roe CM, Grant EA, Head D, Storandt M, Goate AM, Fagan AM, Holtzman DM, Mintun MA. Pittsburgh Compound B imaging and prediction of progression from cognitive normality to symptomatic Alzheimer disease. Arch Neurol. 2009 Dec;66(12):1469-75. PubMed PMID: 20008650.
2: Storandt M, Mintun MA, Head D, Morris JC. Cognitive decline and brain volume loss as signatures of cerebral amyloid-beta peptide deposition identified with Pittsburgh compound B: cognitive decline associated with Abeta deposition. Arch Neurol. 2009 Dec;66(12):1476-81. PubMed PMID: 20008651; PubMed Central PMCID: PMC2796577.
