Specific Type of Beta Amyloid May Be Associated With Alzheimer's

We've known for a long time that those with Alzheimer's disease have a build-up of beta-amyloid protein in their brains. However, autopsies have revealed that some people who never developed Alzheimer's also had beta amyloid in their brains. The question of whether beta amyloid actually causes Alzheimer's disease has puzzled scientists for years.

Drs. Ganesh M. Shankar and Dennis J. Selkoe -- along with others at Harvard Medical School, University College of Dublin, and Trinity College of Dublin -- may have discovered a clue to this mysterious phenomenon. By conducting autopsies of those with Alzheimer's, those with another type of dementia, and those with no dementia, they found three different types of beta amyloid in the subjects' brains: one-molecule, two-molecule, and three-molecule. Almost all of the brains contained some level of beta-amyloid protein, but only the two-molecule variety was specifically related to Alzheimer's disease.

This could explain why some people who never develop Alzheimer's disease still have beta amyloid in their brains -- the protein could be the one- or three-molecule type and, therefore, Alzheimer's did not develop.

The study doesn't prove that two-molecule beta amyloid causes Alzheimer's, but it certainly reveals more than we've ever known before about how beta amyloid relates to the disease.

For more information:

• What Is Alzheimer's?
• What Causes Alzheimer's?

Illustration © Alzheimer's Disease Education & Referral Center