The document provides an overview of the human brain and Alzheimer's disease: 1. It describes the major parts and lobes of the brain, as well as structures like the hippocampus that are affected early in Alzheimer's. 2. As Alzheimer's progresses, plaques and tangles form throughout the brain, damaging neurons and leading to tissue loss. 3. This neurodegeneration and shrinkage impacts nearly all brain functions and abilities as the disease advances from mild to severe stages.