Alzheimers and other diseases which cause dementia symptoms are physical diseases. The symptoms of the disease are the result of cell death in various parts of the brain.
|Brain comparison image from alz.org|
Over the course of the disease, Alzheimer's can result in about 140 grams (4.9 oz) of matter being lost. Given that the brain starts at about 1360 grams (48 oz), that means that about 10% of a person's brain is lost to the disease.
Alzheimer's changes the whole brain
Loss of Brain Volume Could Flag Alzheimer's