Generally, the symptoms of Alzheimer's disease take years to develop and gradually worsen over time. But in some people, the disease progresses more rapidly, and produces more severe symptoms. Now, researchers may have uncovered the reason why the course of Alzheimer's disease varies from person to person.

What Are Beta-Amyloid Fibrils?

To date, most research on Alzheimer's disease has centered on the identification of amyloid plaque deposits in the brains of people with the disease. Scientists know that amyloid plaques are made up of protein structures known as beta-amyloid fibrils but, until recently, no one has been able to study fibrils directly.

Researchers at the National Institutes of Health (NIH) and University of Chicago found a way to extract bits of beta-amyloid fibril from the brain tissue of deceased people who had varying degrees of Alzheimer's disease to grow more fibrils in their lab. The researchers found that fibrils from each person had a different molecular structure. This led to the theory that the variances depend on the environment in which the fibrils grow and that the specific form may determine variations in the course of the disease.

"From previous work on beta-amyloid fibrils, we knew that the fibrils can come in several varieties, and we wanted to see if the same varieties exist in Alzheimer's disease," explains Robert Tycko, PhD, principal investigator in the Laboratory of Chemical Physics at NIH. "It was a surprise to find that individual patients had a single fibril structure but that the structure varied from patient to patient."

Tycko and his team are currently testing whether these fibril variations are in fact related to individual variations in the development of Alzheimer's disease.

What the Research Means for People With Alzheimer's Disease

While this discovery means more for scientists right now than it does for patients, it could pave the way for the development of better diagnostic tools and treatments in the future by directing research more specifically toward fibril structures. More specifically, now that scientists can characterize fibrils, they may be able to find ways to identify them through specific imaging techniques and ultimately block the growth of those that are more likely to cause Alzheimer's disease.

Robert Tycko, PhD, reviewed this article.


Jun-Xia Lu, Wei Qiang, Wai-Ming Yau, et al. "Molecular structure of b-amyloid fibrils in Alzheimer's disease brain tissue." Cell 12 Sep 2013 154(6):1257-1268.