Alzheimer's disease neuropathology - stages

Professor Donna Wilcock describes the neuropathology of Alzheimer's disease as it progresses from the hippocampus to other brain areas.

The staging of Alzheimer’s disease, called the Braak and Braak staging, is based on the movement of the pathology throughout the brain. In the earliest stages of Alzheimer’s disease, you see the pathology in the hippocampus and a part of the cortex that sits behind the hippocampus, called the entorhinal cortex. These seem to be the earliest parts of the brain affected, and this reflects in the clinical outcome, because the hippocampus is responsible for the formation of new memory. The stereotypical behavior of an Alzheimer’s patient that I think everybody out there thinks about is that they can talk about what happened to them 50 years ago during the war, let’s say, but they do not remember what they had for breakfast. So, it’s the remembering what you had for breakfast that the hippocampus does – this is the formation of new memories. As the disease progresses, the pathology seems to move up through the other cortical areas that are called association cortices, and this is where you tend to pull together bits of information from, let’s say, your visual memories, your memories of smells, your memories of taste. All of these things come together in the association cortices. And so, as these become affected, this is when you start having problems with recalling things that maybe happened a long time ago. At this point they may not remember their children and their parents, or remember the names of their grandchildren. Then, as it moves even further, then the Alzheimer’s [disease] patients seem to lose a sense of taste and smell, so they may eat some chocolate, but it tastes to them, in their recall of that, it tastes like curry, let’s say. So, they are not able to pull the different things together and come up with the correct response. Ultimately, the respiratory centers of the brain get affected, the chewing motor mechanisms become affected, and that is very late in the disease process.