Is Alzheimer's disease infectious?

The national media made a tragic mistake in labeling Alzheimer's disease as “infectious.” The issue emerged from a highly regarded series of technical reports that described how a protein related to Alzheimer's disease might move from one cell to a neighboring cell. The word “infect” was used to describe an event that may be happening in a single person's brain. The scientific papers do not suggest that the disease might be able to move from one person to another through normal interactions.

Catherine Clelland, Ph.D. of Columbia University, worked on one of the studies quoted in the media and has received prior funding from BrightFocus.  She explained:

Our study highlighted that different regions of the brain become altered by Alzheimer's disease over time, through spreading of abnormal tau protein from cells in regions where abnormal tau is initially present, to other, directly connected cells within the brain.  It is important to note that there is no evidence from this work, or those of others in the field, that Alzheimer's disease is infectious, or that people who come into contact with Alzheimer's patients are at risk.

It is true that, in animal studies, it has been shown that removing portions of an Alzheimer's brain, and surgically implanting it inside a healthy brain, can sicken the previously healthy cells. That is obviously a highly unlikely occurrence in humans. As suggested by Dr. Clelland and others, there is no evidence suggesting that animals or humans living and interacting with one another normally can contract the disease from each other.

Unfortunately, the media picked up the word “infection” and used it erroneously in their reporting. That term functions as a way of scientifically describing how a protein might move between cells within one person's body.  But the usage of that word has had tremendously negative consequences. It has unnecessarily frightened and isolated many people living with the disease…a disease that is not infectious and not contagious. 

In contrast, the engagement, exercise, and mental stimulation that might be found in social environments are believed by some scientists to play a positive role in helping lessen the burden of Alzheimer's disease. Patients and families suffering with Alzheimer's disease have been hidden from society for far too long. Quite the contrary, we need people talking about Alzheimer's and interacting with others to help end this terrible disease. 

Definitions:  “Infectious” is something that can cause disease; “contagious” is passable between people.

Resources:

• Alzheimer's Toolkit (Information to Help You Understand and Manage Alzheimer's Disease)
• Expert Articles on Alzheimer's
• Questions and Answers about Alzheimer's
• Is Alzheimer's Contagious?