Marking the markers of Alzheimer’s disease

Glen Paul: G’day, and welcome to CSIROpod. I’m Glen Paul. It might surprise you that a definitive diagnosis of Alzheimer’s disease can only be made after death, through autopsy, linking clinical measures with an examination of brain tissue. While Doctors do have access to various tools and methods to help them determine fairly accurately whether a person who is displaying memory problems has possible Alzheimer’s disease, this often comes at a time when it’s too late to do much about it.

A new screening test being developed by Australian Scientists has taken us a step closer to the early detection of Alzheimer’s disease, and involves blood based biological markers linked to the build up of a toxic protein in the brain which occurs years before symptoms appear and irreversible brain damage has occurred.

Joining me to discuss this breakthrough is CSIRO’s Doctor Samantha Burnham. Samantha, why is early detection of Alzheimer’s so important?

Dr Burnham: By the time Alzheimer’s is picked up people usually have clinical symptoms such as memory loss, and at that point they’ve already had brain damage which is irreversible. So it’s really important that we can detect people early on, and that will actually give us some time to alter the course of the disease, or slow it down.

Glen Paul: OK, so that’s obviously why this is so important. How would the screening test work?

Dr Burnham: So one of the earliest stages in Alzheimer’s disease is the build up of a toxic protein in the brain called Amyloid-beta, and this happens about 17 years before we see clinical symptoms such as memory loss. What we’ve discovered is a panel of blood based markers that will actually indicate how much of this toxic protein someone has in their brain.

Glen Paul: So what made you think of looking for the biomarkers of this toxic protein, and then how did you drill down to find the best or most suitable ones?

Dr Burnham: The toxic protein in the brain is one of the earliest signs of people at risk of getting Alzheimer’s disease, but to actually find out how much of this toxic protein in the brain we need to do quite an expensive brain scan. So we wanted to look for an alternative to that, and obviously blood is a really good medium for a cheap population screen type test.

We started off with a few hundred different possible measurements from the blood, and we used some quite sophisticated mathematical models to look at different combinations of these markers, and get down to the panel that we have.

Glen Paul: And it’s about 17 years the average length you say, but what actually causes this toxic protein to begin to form?

Dr Burnham: So we’re still at the very early stages of Alzheimer’s research and about 90% of what we know has been discovered in the last 15 years or so. So we’re really still trying to drill down what’s going on in this disease.

Glen Paul: So how much mathematical modelling went into this research?

Dr Burnham: That was the main focus of this study was actually to use sophisticated mathematical models, and we used the mathematical models to drill down from hundreds of different possible markers, to the nine markers in our panel.

Glen Paul: And are they the definitive panel do you think?

Dr Burnham: We’re still doing more research, and there’s a few other groups around the world also looking into this, so I think there’s some room for improvement.

Glen Paul: So once we have this advanced warning, what could be done then to slow the onset of Alzheimer’s down?

Dr Burnham: We’re really excited about this study because at the minute the only drugs that are available are to actually combat the symptoms, and now that we have this window to get involved before the brain changes occur, we’re hoping that we may be able to find therapeutics that can actually slow or prevent this disease.

Glen Paul: Who were the participants? How did you call upon them to provide data to the research?

Dr Burnham: The AIBL study recruits people mainly from Perth and Melbourne who are aged over 65, and in that we have people who are healthy, we have people who have mild cognitive impairment, and also some people with Alzheimer’s disease. The participants all complete a number of cognitive tests, they have blood samples taken, a number of them have had brain scans, and also some lumbar punctures. And we look at the data across all of this different information to try and find patterns that indicate risk of disease.

Glen Paul: And who are you collaborating with on this study?

Dr Burnham: The AIBL study is undertaken by researchers from Austin Health, the CSIRO, Edith Cowan University, The Florey Institute of Neurosciences and Mental Health, as well as the National Ageing Research Institute, and the study is supported by the Science and Industry Endowment Fund.

Glen Paul: Hmm. And just getting back to the participants, do you require more volunteers?

Dr Burnham: Yes, we’re definitely looking for volunteers. There’s a website called brainpet.org, and there people can fill out their information if they’re interested in getting involved. We’re really interested in getting people that already have some memory problems, and we ideally would like to do the brain scans, take lumbar punctures, as well as collecting bloods and doing some cognitive testing.

Glen Paul: And with Australia’s ageing population, do you see this test eventually becoming something that a GP administer?

Dr Burnham: We would always want to follow the test up with confirmatory testing such as the brain scans, but hopefully this could be rolled out as a frontline population screen.

Glen Paul: So in the future, when the test becomes available, what groups of people would benefit most from undertaking the blood test?

Dr Burnham: The Alzheimer’s Association suggests that the main risk for Alzheimer disease has been aged over 65, so I think that would be around our target population.

Glen Paul: So what needs to be done then before this test can go public?

Dr Burnham: We need to validate it further, and also look at the logistics of getting this ready for a population screening tool, so we think we’re about five to ten years before this could be rolled out.

Glen Paul: And we look forward to it. Fantastic work, Samantha, I appreciate your time today.

Dr Burnham: Thank you.

Glen Paul: Doctor Samantha Burnham. And to find out more about the research, or to follow us on other social media, just visit www.csiro.au.