Seeking the Causes of Alzheim... Video Transcript

Participants

Peter Davies PhD, David R. Marks MD, Norman Relkin MD, PhD

Summary

While the causes of Alzheimer's are still uncertain, many experts believe the key lies in understanding plaques and tangles, lesions and knots of nerve cell fibers in the brain that are sure indicators of Alzheimer's disease. Join our panel of experts as they discuss current research and theories.

Webcast Transcript

DAVID MARKS, MD: Hi, and welcome to our webcast. I'm Dr. David Marks. Alzheimer's disease is the leading cause of dementia in the United States and, like most diseases, the key to treating it is learning about what causes it. But that's been quite a puzzle, and there are a lot of theories out there. We're going to talk about some of those theories with two experts.

First is Dr. Norman Relkin. He's the director of the Cornell Memory Disorders Program at Weill Cornell Medical College. Welcome.

NORMAN RELKIN, MD: Thank you, David.

DAVID MARKS, MD: Also joining us is Dr. Peter Davies. He's the Resnick Professor of Alzheimer's disease research at Albert Einstein School of Medicine. Welcome.

PETER DAVIES, PhD: Good to see you.

DAVID MARKS, MD: All right, here's the $64,000 question: What causes Alzheimer's disease? Is there any one thing?

NORMAN RELKIN, MD: I think that it's difficult, reading the newspapers, to avoid the impression that everything causes Alzheimer's disease. What I would emphasize is that it is a very specific process. I think the underlying disorder unfolds over a considerable span of one's life. But there are many processes that can influence how rapidly that occurs, and to some extent influence who is more susceptible.

Those processes include some genetic factors, and I think some life exposures or life experiences. The nature of all those have not been clearly worked. What has been worked out is that there is, I think, a common pathway, which differs somewhat from the normal processes of aging.

DAVID MARKS, MD: Let's talk about some of the theories. Give us one of the most common theories about what causes Alzheimer's.

PETER DAVIES, PhD: I don't think there is a single, even a single theory that would explain the cause of the disease. I think where the progress has been recently has been in understanding the path that the disease takes. I think the nature of the initiating event is really still unknown. We don't know why the disease begins in one person at age 40 and another person at 65, another at 85. There are multiple factors.

DAVID MARKS, MD: We're looking at the end result.

PETER DAVIES, PhD: Yes.

DAVID MARKS, MD: One of these theories is the amyloid hypothesis. What is that?

PETER DAVIES, PhD: In Alzheimer's disease there are two characteristic structures that form in the brains of patients. One is the plaque and the other is the tangle, in simple terms. Amyloid --

DAVID MARKS, MD: What is a plaque?

PETER DAVIES, PhD: A plaque is a large and complex lesion in the brain of a patient with Alzheimer's disease. At the core of the plaque is this protein that's deposited, called amyloid.

DAVID MARKS, MD: And what's a tangle, first, before you go on?

PETER DAVIES, PhD: A tangle is formation of tangled fibers within a nerve cell. We need to have, to diagnose Alzheimer's disease pathologically, both plaques and tangles present. So, if you like, there are two competing theories. One that the plaque formation and the amyloid deposition kicks off tangle formation. The other is that tangle formation kicks off cell degenerative, and then amyloid deposition. So there's the plaque and tangle sides to this. DAVID MARKS, MD: And what is amyloid?

PETER DAVIES, PhD: Amyloid is actually, the material that's deposited is actually a small part of a normal brain protein, a protein that's present in all of us. We all make it in our brains and in our big toes. But for some reason, in patients with Alzheimer's disease, large deposits of a small piece of this protein form in the brain.