Which came first, the beta-amyloid plaque or the Alzheimer’s? It’s the plaque, but only one subtype, according to a new report by Harvard researchers in the online journal Nature Medicine and profiled in this TIME article from Sunday.

Physicians and researchers have long noted the presence of these plaques, made up of “sticky” beta-amyloid proteins, in the brains of Alzheimer’s patients, and wondered whether there might be some connection between the plaque and the disease. To complicate things, however, beta-amyloid plaques have also been found in patients with no sign of the disease, making scientists wonder whether the plaques could be an advance warning sign of Alzheimer’s rather than a byproduct of the disorder.

So, how was this chicken-and-egg problem solved? Researchers injected rats’ brains with various subtypes (one, two, or three molecules) of the beta-amyloid protein. Rats who received the one- or three-molecule subtypes didn’t experience any problems, but the two-molecule form of beta-amyloid caused Alzheimer-like symptoms, according to Harvard researchers Dr. Ganesh Shankar and Dr. Dennis Selkoe.

Although these are promising findings in the race to find causes of Alzheimer’s disease and cures for those suffering from the disorder, as the TIME article points out, this study still needs to be replicated to ensure that the results are viable. From there, of course, the next question is why only the two-molecule beta-amyloid protein, not its one- or three-part relatives, is destructive to the brain. Like any scientific problem which appears simple at first, these findings are just the tip of the iceberg — or, perhaps, the egg?

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Amyloid Alzheimer s (9/30/2008)

    Last reviewed: By John M. Grohol, Psy.D. on 25 Jun 2008
    Published on PsychCentral.com. All rights reserved.