Alzheimer’s/Blood Sugar Link

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A new University of Arizona study suggests a possible link between elevated blood sugar levels and risk for developing Alzheimer’s disease. Christine Burns, a researcher at the U of A, will talk about the study.

Richard Ruelas: A new university of Arizona study suggested a possible link between elevated blood sugar levels and the risk of Alzheimer's disease. Here to talk about that is Christine Burns from the U. of A. We'll assume that your research is credible.

Christine Burns: Many thanks.

Richard Ruelas: Tell us what you studied. You looked at brain scans of people who showed some predisposition to Alzheimer's, and some who had no predisposition to Alzheimer's?

Christine Burns: Right. We based our research study on the fact that Alzheimer's disease patients do demonstrate reduced metabolism in some brain areas. Our study looked at healthy folks and how their PET imaging metabolism manifested in PET scans.

Richard Ruelas: Meaning how their brain uses up energy?

Christine Burns: Takes up glucose, correct.

Richard Ruelas: Had there been a link before, some thought that metabolism would affect someone's predisposition to Alzheimer's?

Christine Burns: Correct. We did see there was a pattern of reduced metabolism in certain brain areas. So that was what we based the current study on, that there is this picture, so to speak, of the Alzheimer's diseased brain, with respect to glucose metabolism. In this study we furthered it by looking to see if elevated fasting serum glucose levels in healthy folks were associated with reduced uptake in these same brain areas.

Richard Ruelas: So someone who has lowered -- someone who has the glucose level you're talking about, the fasting glucose, you were trying find a link between that number and whether their brain shows that predisposition?

Christine Burns: Right, an association or a correlation. We were looking to answer the question, if elevated fasting serum glucose rises, are you going see a reduction in the uptake of glucose case in these areas that are relevant to Alzheimer's decease.

Richard Ruelas: And it showed?

Christine Burns: That it did. We see an association between those that are non-diabetic, elevated fasting serum glucose levels and reduced glucose metabolism in A.D. relevant brain regions.

Richard Ruelas: I'm going try to translate. I'm not very intelligent, but I did go to ASU. Someone whose blood sugar is just a little higher than normal, but not diabetic, you found a link between that and their brain not processing glucose?

Christine Burns: We're thinking that as you are within the normal level of fasting serum glucose ranges, as your number, your fasting serum glucose number rises, there are certain areas of your brain that start to not use or metabolize that glucose as well. I don't think we would go so far based on this study to say, if I have a higher level of fasting glucose I'm more at risk. But there's definitely something going on with respect to that relationship.

Richard Ruelas: But there's a link in that, and the link merits further study?

Christine Burns: Of course. Especially since we know that diabetes mellitus has been linked to Alzheimer's risk. Fasting glucose levels are an indicator of diabetes mellitus risk or one of the things die bet ticks track for their own health.

Richard Ruelas: What would be the next study you would want to do to show that link?

Christine Burns: It would be unwise to just assume that fasting glucose serum is the only risk in the indicator to look at, especially with respect to risk for diabetes. I think a future study would include more indicators of poor glucose control, such as insulin. Some folks who struggle with diabetes or pre-diabetes might be used to hemoglobin levels that look at glucose control over time. To include more variables would be something that we'd want to do. We'd also want to look at this question longitudinally or long-term. In this study we just looked at a cross-section of folks who are on average about years of age. We want to see what elevated fasting serum glucose at baseline does across the time span, to both your brain imaging measure and your cognitive or memory and thinking scores.

Richard Ruelas: So right now -- and I guess even the idea that diabetes is linked to reduced brain function or possible risk for Alzheimer's -- let's start even there. Is it a -- does diabetes make it more likely you will get Alzheimer's or is it a risk factor?

Christine Burns: Oh, wow. So those -- sometimes those terms are utilized one and the same. I think I feel comfortable saying that diabetes mellitus is definitely one of the risk factors for development of Alzheimer's disease. It has been established along with age, genetics, as one of the top indicators that someone may go on to develop Alzheimer's disease. It is not one of these risk factors that one has to worry about a definite eventual diagnosis, but it's something I know health care professionals want to keep an eye on, and the research community, as well.

Richard Ruelas: So for those who are, again, in the public we hear studies like this and think, I now must change my behavior. I guess avoiding getting diabetes, having high blood sugar, is probably a good idea for a host of reasons.

Christine Burns: Right. So one of the further extensions of the study that you had alluded to before would be to galvanize the community to get involved. Many of them are in interventions. My background in psychosocial interventions for the delay of onset of Alzheimer's disease, or cardiovascular disease earlier on in development. So at midlife or earlier.

Richard Ruelas: And do we know whether the blood sugar levels in diabetics or those who haven't gotten it yet, does it cause the brain to process sugar poorly? There's just so much coming in? Or is it --

Christine Burns: Yeah, that's a question we haven't answered yet, but it's a good one. The link or the causal link, what is that link? What is the elevated fasting serum glucose doing to brain function or brain structure? That's still a question that needs to be answered. It could be answered with a host of different neuroimaging modalities, as well as neuropsychological functioning tests. There are lots of other scientists in Arizona that would love to contribute to answering that question. There's an association but we don't know the cause.

Richard Ruelas: I always thought there was a protein that, if it's seen in the brain, makes you more likely to have Alzheimer's.

Christine Burns: That's a very good point. That is a biomarker. That's the beta amyloid protein studied here at Arizona through some of the institutions of the Arizona Alzheimer's Consortium. The beta amyloid protein, brain metabolism, hypertension, cholesterol, what researchers here in Arizona and nationally are doing is trying to come up with a model of risk factors that would most likely predict Alzheimer's disease development. So we are indeed not just looking at one isolated risk factor. Fasting serum glucose seems to play a role, but you bring up a very good point, there are a lot of other variables that we need to consider.

Richard Ruelas: And it looks like this study shows this could be yet another --

Christine Burns: Yes, of course. One of the many effects, which is important to remember.

Richard Ruelas: Christine, thanks for joining us this evening, it's a fascinating study.

Christine Burns: Thank you.

Christine Burns:Researcher, U of A;

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