Long before Les Milne began exhibiting the telltale signs of Parkinson’s disease, his wife Joy—a so-called “super smeller” capable of detecting scents too subtle for most people to perceive—sensed that something was afoot. But while Joy first noticed a “sort of woody, musky odor” emanating from her husband some 12 years before his diagnosis, it wasn’t until the couple later attended a Parkinson’s support group that she realized the distinctive smell was linked with the degenerative disorder.
Now, Ian Sample reports for the Guardian, researchers from the University of Manchester have capitalized on Milne’s unusual abilities to identify four compounds responsible for producing the Parkinson’s disease-signaling scent. Their findings, published in ACS Central Science, could one day help doctors detect the disease before symptoms arise, opening up a pathway for preventative treatments that aim to delay the onset of debilitating motor loss function.
Milne and the scientists’ collaborative partnership stems from a chance meeting at a 2012 Parkinson’s U.K. awareness lecture. During the session, Milne—who credits her sensitive nose to synesthesia—asked Edinburgh University neurobiologist Tilo Kunath why those who have the disease bear a singular scent.
“Parkinson’s sufferers often lose their sense of smell so I thought that’s what she was referencing initially,” Kunath tells the Telegraph’s Joan McFadden. “She clarified that she was asking about a unique body odour, which took me by complete surprise.”
To test Milne’s sense of smell, Kunath asked her to classify 12 shirts worn by a mixture of healthy individuals and patients diagnosed with the disease. The results were impressive: Not only did she identify all six of the shirts belonging to Parkinson’s sufferers, but as McFadden notes, she also picked out a shirt worn by a test subject who wasn’t diagnosed with Parkinson’s until eight months after the experiment.
For this latest study, the Manchester researchers recruited 60 volunteers, including 43 patients diagnosed with Parkinson’s and 21 control subjects, from 25 study sites across the U.K. According to Inverse’s Sarah Sloat, the team swabbed participants’ upper backs for sebum, a waxy substance secreted by the skin, and then analyzed these samples with gas chromatography-mass spectrometry. (As BBC News’ Elizabeth Quigley points out, Parkinson’s sufferers are known to produce sebum in greater quantities, making them especially vulnerable to a skin condition called seborrheic dermatitis.)
With Milne’s help, the scientists isolated four compounds associated with the singular Parkinson’s scent: Three—eicosane, hippuric acid and octadecanal—appeared at higher than average levels among Parkinson’s patients, the Scotsman’s Kevan Christie writes, while a fourth, perillic aldehyde, was present at reduced levels.
Moving forward, the team will work with Austrian researchers specializing in REM sleep disorders because a separate study suggests individuals suffering from these issues have a 50 percent risk of developing Parkinson’s later in life. They hope to gauge whether their technique is capable of spotting the degenerative disease earlier than the current method, which involves doctors arriving at a diagnosis using observable symptoms.
At the same time, Sample explains for the Guardian, researchers will test more than 1,000 Parkinson’s sufferers’ sebum, as well as that of hundreds of healthy volunteers, to further confirm the link between specific compounds and the musky odor Milne initially smelled.
Les Milne, the patient whose battle with Parkinson’s provided the impetus for the new study, died in 2015. Reflecting on how the early detection method she has helped pioneer could have impacted her own family, Joy Milne tells BBC News’ Quigley, “It would have changed things dramatically.”
“He became withdrawn, reserved, he had bouts of depression and mood swings,” she continues. “If I had understood what was happening it would have changed our total outlook on life."