The Alzheimer's Association has an easy-to-understand slideshow about how Alzheimer's Disease affect the brain:
Here is another view of how massive cell loss changes the whole brain in advanced Alzheimer's disease. This slide shows a crosswise "slice" through the middle of the brain between the ears.
In the Alzheimer brain:
* The cortex shrivels up, damaging areas involved in thinking, planning and remembering.
* Shrinkage is especially severe in the hippocampus, an area of the cortex that plays a key role in formation of new memories.
* Ventricles (fluid-filled spaces within the brain) grow larger.
Link - Thanks Kathy Dunderdale!