Nearly 10 million people worldwide—a million of whom reside in the U.S.—live with Parkinson’s disease, best known for robbing most patients of their ability to move and, for some, a decline in thinking and reasoning associated with dementia.
While Parkinson’s is incurable, some of its worst symptoms can be relieved and controlled using medications that increase a patient’s levels of dopamine, a vital neurochemical that plummets due to the destruction of neurons in the brain that make it. A major obstacle to getting effective treatment at the right time is identifying the disease soon enough, before patients experience the symptoms brought on by irreversible neuron loss.
But scientists might have just the thing to turn the diagnostic tide. And it involves a nose.
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In a study published on Wednesday in the journal ACS Omega, researchers from China’s Zhejiang University created an “e-nose,” a portable device that can smell odors specific to Parkinson's patients using gas chromatography (a technology that separates chemicals as they vaporize), and a surface acoustic wave sensor (which measures gaseous compounds through their interaction with sound waves).
It may come as a surprise to learn Parkinson's patients have their own eau de parfum. But after a retired nurse in Scotland made the headlines in 2015 for a heightened sense of smell that led to her own husband’s Parkinson's diagnosis, scientists have been scrambling to create a device that could sniff out the disease before physical symptoms start to show.
Over the years, scientists have found people with Parkinson's tend to secrete more sebum (an oily, waxy substance produced by sebaceous glands on the body) than the average person. This sebum blends with other overproduced substances—yeast, enzymes and hormones—to yield certain, unique smells.
To track down these scents, the Zhejiang University researchers swabbed the upper backs of 31 Parkinson's patients and 32 healthy volunteers. Using machine-learning software, they were able to identify three odor compounds that healthy volunteers lacked: octanal, hexyl acetate, and perillic aldehyde.
The researchers then tested the e-nose on sebum taken from 12 Parkinson's patients and 12 healthy people. The artificial bloodhound was found to be about 71 percent accurate in distinguishing healthy sebum from Parkinson's sebum, a figure that went up to 79 percent when each person’s full odor profile was analyzed.
These are encouraging findings, but before the e-nose is ready for clinical deployment, the team needs to test it on many more people to improve the accuracy of the models. They will also need to test whether factors like race affect the e-nose’s performance in any way.
But for now, as the number of people living with Parkinson's in the U.S. is expected to rise to 1.2 million by 2030, a nose might be the best option to snuff out this debilitating disease.
