Analyzing Alzheimer's

Alzheimer's disease is a debilitating neuro-degenerative disease associated with memory loss, dementia and the eventual loss of motor functions. Often it is hard for doctors to officially diagnose someone with the disease until it has extensively progressed. According to Alzheimer's Disease International, nearly 10 million people suffer from dementia in Europe alone, with Alzheimer's accounting for the overwhelming majority of these cases. For years, scientists around the world have tried to come up with better treatments and a cure for the disease, but few have been shown to be particularly effective.

In a new scientific paper published in the January 1, 2012 edition of the Archives of General Psychiatry, a team of Swedish researchers have now shown that it's possible to detect individuals with a high risk of developing Alzheimer's 10 years before they show any outward symptoms. If their technique proves successful, it could become an important tool for managing future Alzheimer's patients.

To learn more, Deutsche Welle spoke with Oskar Hansson, a professor of neuroscience at Lund University in Sweden, and a co-author on the new paper.

Deutsche Welle: We understand that you've been working on Alzheimer's research for some time now and that your research now suggests that it is possible to detect the disease a decade before the outward appearance of symptoms. Is that correct?

Dr. Oskar Hansson: Yes. What we've shown is that you can detect both people who are at high risk of developing Alzheimer's disease 10 years before they develop dementia. The test is not 100 percent accurate, so it's not possible to diagnose the patients before they develop dementia, but you can identify those who have a very high risk of developing Alzheimer's disease in the future.

How did you come up with this test?

Research has been going on in this field for the last 10 years. So these bio-markers, as we call them, beta-amyloid and tau have been known for quite some time to be associated with Alzheimer's disease. What we have shown is that these change during the very early stages of the disease.

So in other words the presence of or change in these bio-markers indicate an increased likelihood of someone developing the disease?

Yes, that's right.

Previously, your research had made a similar finding showing that there could be this detection five years before, and now it's doubled to 10 years. What's changed?

It's true. We've been following our same patients for an additional five-year period. What we've shown is that the disease starts much earlier than some of us thought. What is also interesting from a basic scientific view is that we show that beta-amyloid pathology seems to be the earliest event that precedes tau pathology, which comes later on. We've shown this quite clearly in this study.

These substances that you're looking at, beta-amyloid, and tau, what are they exactly?

Beta-amyloid is a small peptide, a small protein that takes part in plaques that form in the brain in patients that have Alzheimer's disease, which has been known for a very long time. Tau is a protein that is mainly inside the neurons that are affected during Alzheimer's disease. They form what we call "tangles" in the neurons. What we see in the cerebrospinal fluid is that the levels of beta-amyloid is decreased, and that's due to being stuck in these plaques in the brain. However, the tau protein is increased in the cerebrospinal fluid and this might be because the neurons are being damaged and tau leaks outside of the neurons.

How do you find or measure these biomarkers? Do you have to withdraw fluid from the spinal column?

Yes, what we do is called a spinal tap. It's quite an easy procedure. It takes around 15 or 20 minutes to perform. It's not associated with much side effects. Sometimes you have transient headaches in younger individuals. It's generally not done by general practitioners, but rather in memory clinics.

Does the value or quantity of these substances change over time?

Beta levels do not change that much with age, tau levels increase slightly with age in general. But in Alzheimer's disease, they seem to change during the very, very early stages. We know that it's at least five to 10 years before dementia, maybe it occurs even earlier, we don't really know. Then after this change they seem to be stable during the disease.

What implications do you think that your finding has for Alzheimer's disease treatments?

I think that mainly it has implications for clinical trials. Because many of the trials that have evaluated the effectiveness of new types of therapies that aim to slow down or stop the disease have not showed promising results when used in patients that are already demented. So we and many others, propose that you should start these trials earlier, when patients have very mild symptoms. But then of course, you need to identify these individuals.

If you identify these individuals that have very little symptoms, but high risk of developing the disease, the likelihood of finding positive effects of these new therapies will be much higher. Because you can initiate the therapy before you have widespread neural injury and maybe before the changes are irreversible.

Interview: Cyrus Farivar
Editor: Holly Fox