Alzheimer’s could be caused by past infections, researchers say

PBS interview with Rob Moir, Massachusetts General Hospital

More than five million Americans live with the degenerative brain disease that robs people of their memory.  It is the sixth leading cause of death in the U.S. a study led by Harvard University researchers and published this week in the journal “Science Translational Medicine” suggests that Alzheimer’s could stem from the brain’s past attempts to fight off infections.

Joining me now from Boston to explain these findings is one of the study’s authors, Rob Moir.  He’s an assistant professor in neurology at Massachusetts General Hospital and Harvard Medical School.

Rob, thank you so much for joining us. A very big week for you and for those watching Alzheimer’s.  Tell us what your research shows.

ROB MOIR, MASSACHUSETTS GENERAL HOSPITAL: Yes.  Thanks for having me. Yes. So, Alzheimer’s disease and the neurodegeneration you see with it is thought to be caused by a little protein that forms this concrete like substance in your brain called amyloid. Amyloid, it turns out, is actually be an antimicrobial pit pod, that is to say it is a natural antibiotic that defends against infection in the brain, and if you get a virus or a bacteria that gets into the brain, it rises to do better with it and binds to it and then entraps it in these long fibers and eventually entombs it forever.

And as they mount in number, eventually they start to be toxic to our own cells, and that leads to the neurodegeneration.  So, that’s what I bet it does.  Was it important?  Well, we are not saying this directly but what it certainly is very provocative in terms of suggesting is that there is an infection in AD, maybe low level, maybe many different pathogens increase into the brain and it has to form this amyloid around them and this is what drives the disease.

LISA DESJARDINS: What do you think, though, that this could hold promise for?  Is it more promising for finding a treatment for those who have Alzheimer’s?  Or is it more promising for those to identify who might be at risk or both?

ROB MOIR: Well, it is actually both.  So if it does turn out to be an infection, there is a possibility of treating people before they get AD with vaccines, to target those particular bugs so that the pathogens don’t get a chance to infect the brain.

LISA DESJARDINS: Are there some of us who have naturally more of this amyloids or more of this defense system that kicks in than others?  Could that help explain why more are more prone to Alzheimer’s than others?  I think there’s often talk of a genetic link as well to Alzheimer’s.

ROB MOIR: Certainly. It’s like any inflammation response, genetics plays a big part, so does environmental factors.  And we all have an amyloid in our brain once you turn 40 you start to develop the stuff.  But some seem to get it much faster. That could be driven by the genetics, they have a hair-trigger when it comes to immunity, or it could be driven by the fact that they are getting more pathogens sneaking into their brain and there could be a number of reasons for that.

LISA DESJARDINS: Well, we definitely will be paying attention in the months or years ahead to this. Rob Moir, I know your lab did the work on this, of Harvard and Massachusetts General — thank you so much for joining us.

ROB MOIR: Thank you so much for having me.

Watch interview on YouTube