The hippocampus is a structure deep in the brain that helps encode short-term memories. AD damages nerve cells in the hippocampus and the pathways that link the hippocampus to the rest of the brain. This damage leads to short-term memory failure.

When the cerebral cortex is attacked, language skills and ability to make judgments are impaired. Personality changes occur, including emotional outbursts and disturbing behaviors such as wandering and agitation.

Once the entire brain is involved, the patient may be bedridden, incontinent, helpless and unresponsive.