With the rise of new drugs that can target the amyloid-beta plaques in the brain that are an early sign of Alzheimer's disease, new ways are needed to determine whether memory loss and thinking problems are due to Alzheimer's disease or another neurodegenerative disorder. A new study shows that shrinkage in the hippocampus area of the brain is associated with cognitive decline, even in people who don't have amyloid plaques in the brain. The hippocampus plays a role in memory.