In the early 1980s, nurse Joy Milne began to notice a distinct musky odor on her husband. A few years later her husband was diagnosed with Parkinson's disease, but Milne didn't connect the two disparate events until she later joined a Parkinson's charity and started meeting other sufferers. It was here she began to notice every person with Parkinson's disease could be identified by this same unusual and distinct odor.

In 2012, Milne approached a neuroscientist giving a talk on Parkinson's and claimed to be able to smell the disease. The scientist decided to test her claim. Six Parkinson's patients, and six healthy subjects wore clean t-shirts for a single day, and the 12 t-shirts were then individually bagged and presented to Milne. After extensive sniff testing, Milne ultimately guessed 11 out of 12 correctly, only misidentifying one t-shirt as being worn by a Parkinson's patient, when in fact it was a healthy subject.

Since then, a team of scientists has been working to isolate and identify the compounds Milne associated with Parkinson's. Now, after several years of work, the researchers claim they've been successful and suggest the discovery could lead to an early detection test for the devastating disease.

Sebum is an oily substance secreted by the skin. Prior research has revealed that Parkinson's patients tend to excessively produce sebum and the hypothesis was that specific molecules in the sebum secreted by Parkinson's patients was what Milne was smelling.

Using mass spectrometry the researchers zoomed in on samples of sebum from Parkinson's patients, revealing a handful of specific volatile molecular biomarkers were unique to the sebum of Parkinson's patients. The researchers subsequently brought Milne into the laboratory to confirm the odor of these components and she indeed verified they did signal the "smell" of Parkinson's.

It is still early stages for the research, but it's suggested that by tracking the levels of these specific molecules in sebum samples, the disease can be identified in a variety of different stages. Milne has even anecdotally reported that the odor she sensed did rise and fall depending on how effectively her husband's treatment was working. The hope is that as well as leading to an early detection tool, the test could track the progression of the disease in an easy and non-invasive way.

"Now we have proved the molecular basis for the unique odor associated with Parkinson's we want to develop this into a test," says Perdita Barran, a scientist working on the project from the University of Manchester. "This could have a huge impact not only for earlier and conclusive diagnosis but also help patients monitor the effect of therapy. We hope to apply this to at risk patient groups to see if we can diagnose pre-motor symptoms, and assist with potential early treatment."

Milne's husband passed away from the disease in 2015, but her remarkable discovery could improve the lives of millions around the world. Effective clinical tools arising from this research are still a few years away but the ability to detect and track this disease through volatile skin biomarkers has the potential to revolutionize diagnosis and treatment.

The new research was published in the journal ACS Central Science.