Study Finds Potential Link Between Sense of Smell, Alzheimer’s Disease
By Eric Schoch
That sage advice, made famous years ago by writer Douglas Adams in The Hitchhiker’s Guide to the Galaxy, applies equally well now to those who might do some at-home smell testing and wonder what it means about the health of their brain.
In a recent research report, Shannon L. Risacher, PhD, assistant professor of radiology and imaging sciences at IU School of Medicine, and colleagues found that research study participants who had problems identifying different odors were more likely to have a buildup of the protein tau in their brains, or to have some deterioration of brain tissues.
Abnormal levels of tau buildup in the brain are associated with Alzheimer’s disease, particularly the cognitive issues that come with the disease.
The standard olfactory test used in the IU research – the University of Pennsylvania Smell Identification Test, or UPSIT – is available for purchase.
Read on for more on the UPSIT test from Dr. Risacher, as well as what’s next for her research.
Q: You mentioned that people can buy the UPSIT test. If I take the test and find I have some smell deficit…
Dr. Risacher: I certainly would not panic. Some people have never had a good sense of smell. It might be a bad day.
Q: So more seriously, is this a test that’s ready for clinical use?
A: As we said in the article, the interpretation of study needs be taken with grain of salt because it is small. Tau imaging technology is a very new technology, so this would be the first time that anybody has looked at this particular (smell) test in association with tau. The proteins amyloid and tau are two things we worry about with Alzheimer’s disease, and tau is more associated with the actual cognitive decline of Alzheimer’s disease.
So it was an exciting opportunity, even though it’s a small sample, to see whether or not a test like this might be useful for detecting pathology.
Q: If you were a physician, would you use it?
A: I might just to get a sense if there are changes. Whether that means Alzheimer’s disease or another type of pathology, you can’t be clear on that.
What we haven’t done really well in the (scientific) literature and what I would like to do is repeated tests. If you have a progressive decline in your odor identification over a period of a few years, without any other reason for it – you’ve had a broken nose, or problems with your sinuses, there’s lots of things that can affect your smell – then you might want ask if there is something neurological going on, and that would be with your doctor, or ultimately a neurologist.
One thing we try to tell ourselves here is that people are fluid beings. They walk into our office and do a memory test – that’s just one day. What we really need and what we don’t do the greatest job of in science is a fluid measure of how people are changing over time because Alzheimer’s disease doesn’t show up overnight. It probably accumulates over 20 or 30 years. Perhaps that’s where the most information is, how are people changing over time.
Q: What are your plans for future research?
A: With a small grant we’ve had positive results with vision and smell; we haven’t gotten to hearing yet. We want to work with a larger sample size, so we’ll be seeking funding to expand to a larger study.
We also want to bring in subjects with other neurodegenerative diseases to see whether can tease out biomarkers that would be more specific for Alzheimer’s disease.
Our goal is to have all those measures in the same patients. Can we combine them in a way that is complementary and improves our biomarkers. Maybe the olfactory test isn’t enough, but if you have a problem with your vision and your hearing and your smell, is that a better predictor than one alone?
Top photo caption: Shannon Risacher, PhD (Photo by Eric Schoch)