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New insight into why older brains prone to Alzheimer's disease

Kathleen Blanchard's picture
Researchers uncover why aging brain more susceptible to Alzheimer's

No one knows exactly what causes Alzheimer's disease. Researchers know the risk of the most severe form of dementia increases with aging. Researchers at Washington University School of Medicine in St. Louis have now discovered what happens in the brain as we get older to raise our chances of Alzheimer's disease.


Amyloid plaque that consists of amyloid beta 42, along with tau proteins that entangle nerve fibers in the brain destroys memory and thinking.

Changes in the brain that lead to Alzheimer's disease and are thought to occur decades before symptoms occur.

Amyloid is a protein that is normally cleared from the brain.

“We found that people in their 30s typically take about four hours to clear half the amyloid beta 42 from the brain,” said senior study author Randall J. Bateman, MD. “In this new study, we show that at over 80 years old, it takes more than 10 hours.”

See: How you sleep could affect Alzheimer's risk

Alzheimer's disease is associated with clumping of amyloid beta 42. The longer it sits in the brain, the greater the likelihood it will clump.

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The study

Researchers tested study volunteers age 60 to 87; half of the participants had some form of memory loss; 62 had brain plaque associated with Alzheimer's disease.

In addition to physical exam and mental testing, the study participants' production and clearance of amyloid plaque was monitored using a technology that tests cerebrospinal fluid, developed by Bateman and co-author David Holtzman​, MD.

The results, published in the Annals of Neurology showed people that cleared amyloid 42 more slowly were most likely to have symptoms of Alzheimer's disease, which was seen in older patients.

The protein is thought to move to spinal fluid where it enters the brain where it is either broken down and absorbed or forms plaques.

The researchers hope to pinpoint where the breakdown and disposal of amyloid 42 disposal slows as we get older in hopes of finding new treatments.

Image credit: Wikimedia Commons