What comes first, beta-amyloid plaques or thinking and memory problems?

The scientific community has long believed that beta-amyloid, a protein that can clump together and form sticky plaques in the brain, is the first sign of Alzheimer's disease. Beta-amyloid then leads to other brain changes including neurodegeneration and eventually to thinking and memory problems. But a new study challenges that theory. The study suggests that subtle thinking and memory differences may come before, or happen alongside, the development of amyloid plaques that can be detected in the brain. The study is published in the December 30, 2019, online issue of Neurology, the medical journal of the American Academy of Neurology.