JUDY WOODRUFF: An estimated five million Americans have Alzheimer's disease, and there's no known cure. But a new trial offers some early promise for tackling the disease at its early stages, using a daily spritz of insulin.
Ray Suarez has our update.
RAY SUAREZ: The idea behind the trial was relatively simple: Patients with Alzheimer's disease lose critical insulin in the brain as their condition worsens. What if insulin could be supplemented?
Researchers at the VA Medical Center in Washington state did just that. They gave patients with early-stage Alzheimer's disease a nasal spray containing insulin twice a day for four months. Early results published in The Journal of Neurology today were encouraging. Insulin delayed memory loss and other problems.
And she joins me now.
And, Professor, a lot of people are familiar with insulin as the hormone that helps metabolize fat and carbohydrate. What does it do in the brain, and what led people to wonder if supplementing it might help with Alzheimer's?
SUZANNE CRAFT, Veteran Affairs Puget Sound Health Care System: Well, you're right. The most well-known role of insulin is in treating diabetes. But, in the last few years, we have come to understand that insulin has a number of very important roles to play in the brain. In particular, it's very critical for memory, for memories -- for memories to form.
And it also protects against the toxic effects of proteins, like the amyloid protein, which is the protein that collects in the brains of patients with Alzheimer's disease. And, interestingly, patients with Alzheimer's disease appear to have a deficiency of insulin in their brain or the insulin that is there doesn't work effectively.
So, that led us to wonder whether or not supplementing insulin would be of benefit to patients with Alzheimer's disease, possibly to improve their symptoms or to ameliorate their pathology.
RAY SUAREZ: Well, we're still early in the course of this study. And it was a small one, right? How did you pick the people who were used in this research?
SUZANNE CRAFT: Yes, you're right. It is early in the life of this area of research.
Our participants were patients with very early Alzheimer's disease. They either had the prodromal condition known as amnestic mild cognitive impairment or they had very mild, very early Alzheimer's disease. So they were volunteers who came to our clinics to be in our study.
RAY SUAREZ: And once they used this insulin, what could you observe happening inside their brains?
SUZANNE CRAFT: Well, we had three groups.
We had a group who received a placebo, an inactive substance. And we had two groups who received different doses of insulin. And as you said, they received insulin for four months. And what we saw were significant improvements in memory for the participants who received the lower dose of insulin.
And we also looked for some of our participants at the way the brain was able to use glucose. We know that that is a problem for patients with Alzheimer's disease. And we observed, for the placebo group, their brain used less glucose over time, which is a common pattern in Alzheimer's, whereas, for our insulin-treated folks, they had either no change in their glucose use in their brain or in some areas even an improvement.
RAY SUAREZ: How do you test someone with mild cognitive impairment? How do you check whether they have improved or at least slowed down in their advance? What tools do you use?
SUZANNE CRAFT: Well, there are a number of different memory tests that have been developed.
And the test that we used is one of the most sensitive to the very earliest stages of memory loss. It's called a story recall test. And so the participants hear a story that's read to them and then we ask them to tell us back right away all of the details of the story that they have just heard. And then we wait 30 minutes and ask them again to recall all of the details.
And so the amount of information that they're able to hold on to over that 30-minute period is a very good indicator of the state of their memory. And what we observed was that the participants that were treated with the lower dose of insulin were able to remember more details over the 30-minute period after four months of treatment than was the placebo group.
RAY SUAREZ: So you had this promising initial result in this small group in phase two. Where do you go from here? And how do you ramp up? What are you looking for?
SUZANNE CRAFT: Well, the next phase is going to be very important.
What we need to do is to administer insulin for a longer period of time than four months. We need to know that this is going to be safe when it's given over a longer period. And we also have some reason to believe that it will be even more effective if it's given for a longer period of time.
So that's a very important next step. And our plans are to give it for a year-and-a-half. And then the other aspect of this is that we need to bring this into a larger arena. And we will be proposing a study that will be carried out in many centers across the country, in centers where there are Alzheimer's research centers that are funded by the National Institute of Health.
And so we will be -- we will be improving the study in terms of having it be translated into a larger scale and for a longer period of time.
RAY SUAREZ: There are already millions of people who are taking insulin routinely. Is there anything we can learn from taking a look at them?
SUZANNE CRAFT: Well, that's a very good question.
Of course, the people who are taking insulin routinely are folks with diabetes. And we know that diabetes is a risk factor for Alzheimer's disease, that if one has diabetes, one is more likely over one's lifetime to develop Alzheimer's disease. So it's very important for folks with diabetes to control their diabetes well.
And what we have learned is that, if you are able to control your diabetes well, then you are able to reduce the risk of developing Alzheimer's.
RAY SUAREZ: Stressing again that it is still early days, if all goes well and the results continue to be promising, how far out are we talking about, one, three, five years, before we get this as an on-label use for insulin?
SUZANNE CRAFT: Well, our hope is, if we're able to start this next phase of study by next summer -- that's our plan, if we are able to receive and funding -- then, within three to four years, we should have a very good idea of whether this will work as a therapy in the current form that we're testing.
But I also want to point out, what -- in terms of a proof of concept, what our study indicates is that therapies that are directed at correcting the insulin abnormality in Alzheimer's disease may be very fruitful lines of research. So I'm sure that the study will also generate a large number of studies looking at other ways of improving insulin function in the brains of patients with Alzheimer's disease.
RAY SUAREZ: Professor Suzanne Craft, thanks for joining us.
SUZANNE CRAFT: Thank you.