12. Gliadegenerative disease

Many degenerative diseases of the brain, especially Alzheimer’s Disease, Parkinson’s Disease, and Amyotrophic Lateral Sclerosis (Lou Gehrig’s Disease) have a curious aspect. In all of them, the first thing to go is the sense of smell. Why smell? No one knows. Many reasons for this might exist—the disease somehow attacks the neurons transmitting the sense of smell into the brain. Maybe some primitive evolutionary imprint has left its mark on our nose and it just gives up when the brain begins to degenerate in any area. However, we are taught that in Alzheimer’s, the point of attack is the hippocampus, which is the area responsible for forming new memories—the area cut out of Brenda Milner’s famous patient HM. In Parkinson’s, the debilitated....