Can a Simple Sniff Test Detect Parkinson's Disease?

"You Smell!" A phrase often used by children may have new meaning. New research suggests that it is possible to detect Parkinson’s disease (PD) by sniffing someone’s skin. Having “a nose” is essential to perfumers, truffle hunters, and wine experts. Some bouquets are floral and the scent of PD seems to be musky. Whether this will prove a reliable diagnostic tool will require more research.

Parkinson’s disease, a neurodegenerative disorder, has no diagnostic test to determine if an individual has Parkinson's - especially early on when symptoms may not be as apparent. There are a number of conditions that are like Parkinson’s that are generally ruled out during the diagnostic process and often brain imaging is done to evaluate symptoms that appear long after PD has developed.

If we can find a way to recognize and diagnose Parkinson’s earlier, perhaps advances in medicine could slow the progression of the disease and help us learn more about the biochemical pathways that cause PD.1

The sniff test

The story behind the research now being done is unique. Joy Milne, a resident of the UK, asked a Parkinson’s researcher if people with Parkinson’s smelled differently than other people. She suggested that she had detected a distinct odor from her husband nearly 10 years before he was diagnosed with Parkinson’s at age 45.2 The researchers at the University of Edinburgh were intrigued and created a small study to test her ability to sense the smell of a group of 12 people. Joy Milne was able to assess 11 of the 12 cases correctly. The one person she identified by smell as having Parkinson’s, but was considered a false-positive, was someone who had not yet been diagnosed with Parkinson’s and developed it some months later. As it turned out, Joy was giving the medical team the diagnosis before they were able to make it.1,3

Smells as biomarkers

Further research allowed the experts to identify the “volatile compounds” in T-shirts worn by the people with PD in order to identify the molecular signature - to identify what causes a specific smell.1 New funding will allow research into a larger group to determine if there is a secretion effect from PD medications as well as selecting different cohorts within the PD population to see if additional differences can be detected.

Studies will also consider some of the information gathered from Joy and others who could smell Parkinson’s. Whether the odors could be identified before the disease onset or when their loved ones smelled more when their symptoms were not well controlled. Researchers say they will be looking for biomarkers in the skin as well as in blood and spinal fluid. Those may become tools that aid in earlier PD diagnoses.

Les Milne, a physician, died in 2015 at age 65. One of his last wishes was that his wife, Joy, continue to pursue the role her ability to smell the condition might play in future diagnostic research.

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