Scientists at the University of Manchester in the UK have developed a test for Parkinson’s disease using information from a woman’s unique, heightened sense of smell that can detect the condition.
Perth, Scotland-based Joy Milne noticed that her now late husband Les, a former physician, smelled differently when he came home from work one day. She recalls that he had an unpleasant musky yeast-like scent on him, which was very different from his usual musky smell that she loved. She noticed the change more than 12 years before he was diagnosed with Parkinson’s at the age of 45. Les passed away in 2015.
According to the BBC, Milne, now 72, was able to connect the odor to the disease after meeting people at a Parkinson’s UK support group after Les was diagnosed. She was able to detect the same distinctive smell in other Parkinson’s patients in the group.
Because of this, Milne, a retired nurse, has been nicknamed “the woman who can smell Parkinson’s.”
Medically, Milne’s condition is known as hereditary hyperosmia, a rare disorder that results in a heightened sense of smell.
Intrigued by Milne’s olfactory observations, the University of Manchester researchers set out to investigate what exactly it was that she could smell on Parkinson’s patients, and whether this could be leveraged to help identify individuals with the neurological condition.
The researchers worked with Milne and developed a simple skin swab test method, which they claim is 95 percent accurate in detecting individuals with Parkinson’s.
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Parkinson’s is the fastest growing neurological disorder worldwide and the most common movement disorder. Its prevalence has doubled in the last 25 years, according to the World Health Organization (WHO). The global health agency says that in 2019, there were an estimated 8.5 million individuals globally with Parkinson’s with 5.8 million disability-adjusted life years, an increase of 81 percent since 2000, and the disease caused 329,000 deaths, an increase of over 100 percent since 2000.
There is no cure for Parkinson’s nor any definitive diagnostic test. Patients are diagnosed through the observation of symptoms, some of which include difficulty walking, speaking, cognitive impairment and a tremor.
In their preliminary work in developing the diagnostic test for Parkinson’s, the scientists asked Milne to smell T-shirts that were worn by people who had Parkinson’s versus those who did not. Milne correctly identified shirts that had been worn by patients with the disease. Additionally, she also identified one that smelled like the disease from the group without Parkinson’s and eight months later, the individual to whom that T-shirt belonged, was diagnosed with the condition.
The scientists thought the scent may be caused by a chemical change in skin oil, known as sebum, triggered by the disease. Working with this hypothesis, they were able to identify a unique chemical signature in the skin linked to the condition.
To develop the new test for Parkinson’s, the researchers first identified biomarkers in skin swabs taken from the backs of individuals (as that area of the body is less washed than others) that could be linked to the disease.
They compared the skin chemical profiles of 79 people with Parkinson’s with a control group of 71 healthy individuals using mass spectrometry. Of the more than 4,000 unique compounds that the researchers found in the samples, 500 were different between people with Parkinson’s and those without.
The research study is published in the Journal of the American Chemical Society.
While the detection method is still in early development and only lab-based currently, the research team is excited at its potential to detect Parkinson’s at early stages. The method needs to be validated in a clinical lab before it can be used as an official diagnostic test clinically.
Professor Perdita Barran, lead investigator on the research, told the BBC that there is currently no chemical test for Parkinson’s disease and many thousands of people are on waiting lists for a neurological consultation.
She said developing a confirmatory test that could be used by a physician would be “transformative.”
“At the moment we have developed it in a research lab and we are now working with colleagues in hospital analytical labs to transfer our test to them so that it can work within an NHS environment,” she said.
“We are hoping within two years to be able to start to test people in the Manchester area.”
Milne says the night before her husband passed away, he had made her promise that she would investigate her sense of smell to help “make a difference.”
Since then, Milne has done just that. Her olfactory condition has led her to participate in other disease research areas, including cancer and tuberculosis (TB).
However, she told the Guardian that her special ability can be a double-edged sword. “I have to go shopping very early or very late because of people’s perfumes, I can’t go into the chemical aisle in the supermarket,” she said.
“So yes, a curse sometimes but I have also been out to Tanzania and have done research on TB and research on cancer in the US — just preliminary work. So it is a curse and a benefit.”
She said she can sometimes smell people who have Parkinson’s while in the supermarket or walking down the street. Given the ethical concerns around disclosing such information, medical ethicists have told Milne that she cannot approach people and tell them anything.
“Which GP would accept a man or a woman walking in saying ‘the woman who smells Parkinson’s has told me I have it?’ Maybe in the future but not now.”
The ultimate goal of a test for Parkinson’s would be to detect the disease early so that interventions can begin early. Milne says had her husband been diagnosed earlier, she could have had more momentous times with him.
James Jopling, the Scotland director of Parkinson’s UK, told the BBC that the discovery could make a real difference to people living with the disease.
“Currently with no definitive test people have to wait months or years to be diagnosed so the fact that you could get the treatment and support you need and that researchers could begin new treatments is incredibly important,” he said.
Parkinson’s disease is usually diagnosed in later stages when the brain has undergone significant neurological damage. Milne says this is not acceptable. “I think it has to be detected far earlier — the same as cancer and diabetes, earlier diagnosis means far more efficient treatment and a better lifestyle for people.”