Sniffing out Parkinson’s disease

Olfactory gift of retired nurse could lead to early Parkinson’s diagnosis technology

The sense of smell is one of the least well understood of the senses. It has long been known that some dogs, and less commonly even humans, seem to be able to detect certain diseases from an odour on the breath or the skin. Researchers at University of Manchester’s Institute of Biotechnology (MIB) and investigated such a talent exhibited by one of their colleagues, and believe they may be able to translate her talent into a technological diagnostic technique.

Parkinson's
Joy Milne (left) and Prof Perdita Barran Image: University of Manchester

Joy Milne, a retired nurse from Perth who is also a honorary lecturer at the University of Manchester, noticed some years ago that she could detect a musky odour on the skin of people suffering from Parkinson’s. She first noticed it on her husband, a decade before he was clinically diagnosed with the disease when he was 45. For the past three years, she has been working with the MIB on determining what it was that she was smelling. It was already known that Parkinson’s can cause excess production of sebum, the fatty bio fluid exuded by the skin as a natural moisturiser and protective barrier. In the journal ACS Central Science this week, the MIB team explains how it used mass spectrometry to analyse sebum from people who had previously been diagnosed to identify volatile components that might be producing the smell. Mrs Milne then checked the odour of these components determine which, if any of them, she could recognise.

The research took in 60 subjects, both with and without Parkinson’s. The team detected three specific compounds in Parkinson’s sebum: hippuric acid, eicosane and octadecanal, all of which seem to be connected with altered levels of neurotransmitter compounds found in the brains of Parkinson’s patients, along with other known biomarkers for the condition. By considering the levels of these characteristic molecules, the team, led by Perdita Barran, professor of mass spectrometry at MIB, has determined a model that they claim can identify and diagnose Parkinson’s at all states of the condition.

Parkinson's
Schematic showing how odour molecules were extracted from sebum and identified using gas chromatography/mass spectroscopy. Image: ACS Central Science

Currently, diagnosing Parkinson’s is extremely challenging. It does not show up on most scans, and there is no recognised chemical test. In many cases, it is diagnosed from symptoms and whether they respond to known treatments. This means that many people are diagnosed after having the condition for some time, whereas it is believed that starting treatment early could delay the onset of serious symptoms significantly. “Now we have proved the molecular basis for the unique odour associated with Parkinson’s we want to develop this into a test,” said Prof Barran. “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.”

Professor David Dexter, deputy director of research at Parkinson’s UK, said: “Finding changes in the oils of the skin in Parkinson’s is an exciting discovery that was sparked by a simple conversation between a member of the public and a researcher.

“More research is needed to find out at what stage a skin test could detect Parkinson’s, or whether it is also occurs in other Parkinson’s related disorders, but the results so far hold real potential. Both to change the way we diagnose the condition and it may even help in the development of new and better treatments for the 145,00 people living with Parkinson’s in the UK.”

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