What Are Beta-Amyloid Plaques and Tangles?

May 4, 2009 -- Question: What is beta-amyloid, and what are the plaques and tangles I hear about when doctors talk about Alzheimer's disease?

Answer: The diagnosis of Alzheimer's disease is only confirmed after death, when doctors look at the brain under a microscope. There, we can see the buildup of abnormal substances. Inside nerve cells, we see strings that we call tangles.

In between nerve cells, there are clumps of material that we call beta-amyloid.

Amyloid is a very sticky substance and as it's released from nerve cells it clumps together to form these plaques.