Scottish Joy Milne made headlines in 2015 with an unusual talent: her ability to track down people with Parkinson’s disease, a progressive neurodegenerative disease that affects millions of people. Since then, a group of scientists in the UK has worked with Milne to identify the molecules that give Parkinson’s disease its special smell. The team has now focused on these molecules and developed a simple skin test to detect them.
Milne, a 72-year-old retired nurse from Perth, Scotland, suffers from hereditary hyperosmia, a condition that makes people sensitive to smell. She discovered that she could smell Parkinson’s disease after noticing that her late husband Liz smelled of musk that she had never seen before. Finally, when he was diagnosed with the disease many years later, she linked this change in smell to Parkinson’s disease. Leigh passed away in 2015.
In 2012, Milne met Tilo Konath, a neuroscientist at the University of Edinburgh, at an event organized by the UK charity Parkinson’s. Despite their initial skepticism, Kunath and his colleagues decided to test Milne’s claims. They gave her twelve T-shirts, six people with Parkinson’s disease and six healthy people. I identified the disease correctly in all six cases – and the only T-shirt from a healthy person that I classified as Parkinson’s belonged to someone who was diagnosed with the disease less than a year later.
Kunath then teamed up with University of Manchester chemist Perdita Baran and colleagues to search for the molecules responsible for the change in smell Milne can sense. The researchers used mass spectrometry to determine the types and amounts of molecules in a sample of sebum, an oily substance placed on the surface of the skin. They discovered changes in fat molecules, known as lipids, in Parkinson’s patients.
In their latest study, the researchers reveal the results of a simple skin swab test to detect the fatty fingerprint that indicates Parkinson’s disease. By comparing sebum samples from 79 people with Parkinson’s disease with 71 people without the disease, the team identified a large group of fats that can be detected in minutes. This is done using a special type of mass spectrometry in which material is rapidly transferred from the smear to the analyzer using a piece of paper.
“I think it’s a very promising group of biomarkers,” said Blaine Roberts, a biochemist at Emory University, who was not involved in the study. He adds that one of the biggest unanswered questions is how accurate this test is. Although the authors of this study reported a detailed chemical profile of Parkinson’s disease, they do not know how accurate this profile is. According to Baran, their test, based on unpublished data, appears to be able to determine whether someone has Parkinson’s disease with over 90 percent accuracy.
The sebum-based swab test is new and has clear advantages, such as ease of sample collection, says Thiago Otero, a neuroscientist at the University of Göttingen in Germany who was not involved in the study. Otero wonders if people with illnesses that share symptoms and illnesses with Parkinson’s, such as multi-system atrophyalso have similar chemical signs.
The team is now working with local hospitals to determine if this sebum-based test can be performed in clinical laboratories — an important step in determining whether it can serve as a diagnostic tool. Ultimately, Baran says, it is hoped that the test will be used to identify individuals who have been referred by their primary care physician to a neurologist on suspicion of Parkinson’s disease so that they can obtain a diagnosis more quickly.
The skin swab test will allow these patients to send skin swabs for analysis in the hospital laboratory and to identify those who need help urgently. Baran’s research team approaches people on the waiting list to see if they’d be willing to participate in a trial to see if these skin swab tests could be effective in speeding up the screening process.
Baran and her colleagues are also working with a group from Harvard University to determine whether sebum-based biomarkers are detectable in people who have not yet received a diagnosis of constipation, decreased sense of smell, or other early signs of Parkinson’s disease.
Milne has also inspired other research groups. This year, researchers in China published an article on the electronic nose — an AI-based sensor similar to the olfactory organ — that searches for molecules in lipid PwPs. Other scientists in China, the United Kingdom, and elsewhere have trained dogs to detect the disease.
Parkinson’s disease may not be the only disease Milne has. She has also reported noticing a unique scent in people with Alzheimer’s disease, cancer and tuberculosis and is working with scientists to see if a specific scent can be found for these diseases.
Milne hopes that this work will eventually benefit patients with these conditions. Milne said in 2015: “My husband suffered from Parkinson’s disease for 21 years after his diagnosis, but had it many years before that. I would like to see people not suffer the way he did.”