Our sense of smell is a greatly under appreciated skill. Not only does it provide us with vast quantities of sensory information, but for the medical profession too our ability to smell can be a biomarker for long-term conditions.
It is already known that losing one’s sense of smell, or suffering a change in the way we smell could be an early indicator of Alzheimer’s, often long before conventional symptoms are shown.
Yet despite how useful smell tests are, very few of us undergo them.
“People have their vision and hearing tested throughout their lives, but smell testing is exceedingly rare,” says neuroscientist Leslie Vosshall.
Now a team at Rockefeller University, including Vosshall, believe they’ve been able to develop a brand-new type of smell test that cuts through the inaccuracies of conventional testing and provides a new, more reliable biomarker for certain diseases including Alzheimer’s and Parkinson’s.
The current smell tests rely on a patient’s ability to detect and then identify a very specific odour. Vosshall uses the example of rose-scented phenylethyl alcohol.
Now while most of us could probably manage to identify it, there are some people who wouldn’t be able to but would still have a completely normal sense of smell.
That doesn’t mean they have an underlying condition, it just means they can’t smell rose molecules. Then there’s the issue that some patients might not live in an area where this flower grows so wouldn’t actually know what it was in the first place.
All of this bias can add up to misdiagnosis and that’s something that Vosshall and her colleague Julien Hsieh want to avoid.
To combat this bias the pair created something called a “white smell”. This works by mixing many different odours together in order to make something completely unfamiliar.
The test then involves asking patients to identify white smells with overlapping ingredients and then white smells at lower concentration levels.
The best thing about the test is that it doesn’t matter if a person can’t identify a single odour, instead they’re identifying the problems around smells.
“We’re really excited about these new tests,” says Vosshall. “They focus on the problem of smell itself, because they don’t force people to match smells to words.”
The team have conducted clinical trials at both The Rockefeller University Hospital and Taichung Veterans General Hospital in Taiwan and both tests have shown to be more accurate than conventional smell tests.
“The goal is to use changes in the sense of smell, along with other biomarkers, to identify underlying causes of these neurological disorders very early, and so potentially improve treatment,” says Hsieh.