The brain on the left is a healthy brain, the brain on the right is from a person who had Alzheimer’s disease. This brain was full of the beta amyloid plaques and tau tangles two if the hallmarks of Alzheimer’s disease.
This brain also looks smaller. Severe cortical shrinkage or atrophy occurs and this makes it very difficult for the brain to function as it normally would.
Although you cannot see it in this picture, the hippocampus, which plays a very important role in also shrinks and this makes it very difficult for the person to make new memories.