An olfactory signature for Parkinson’s?
Original article: Discovery of Volatile Biomarkers of Parkinson’s Disease from Sebum, ACS Central Science: March 20, 2019.
A collaborative study between a Super Smeller and UK researchers has identified a combination of chemical compounds found in the sebum of people with Parkinson’s.
Why is it important?
This work could translate directly into a measureable, non-invasive biomarker for Parkinson’s which could help in early detection.
Sebum is a waxy, fatty fluid produced naturally by skin. Although it is known that certain diseases can actually be detected through body odour, like typhoid or diabetes for example, this has never to date been reported for Parkinson’s.
This study was based on the serendipitous discovery of Joy Milne, a “Super Smeller” or person with an extremely keen sense of smell, who was able to detect her husband’s Parkinson’s 12 years before he was diagnosed. The aim was to discover what sort of chemical compounds in sebum may be responsible for this odour, and discover which of these may be associated with Parkinson’s.
The researchers analysed 64 swabs of gauze that had been used to sample sebum from the upper back of 21 people without Parkinson’s (controls), and 43 people with Parkinson’s who were either drug naïve or receiving regular medications. They were recruited from 25 centres across the UK.
These samples were analysed chemically in order to identify the main compounds. They were also presented to the Super Smeller to look for correlations with her descriptions of whether she described a scent as “very strong” and “musky”. The researchers found this was associated with three chemicals (hippuric acid, eicosane, and octadecanal). These were then mixed independently for the Super Smeller to blindly rank in order of increasing intensity of PD-like smell. She was able to detect the whole range of these different concentrations.
Interestingly, the researchers found no differences in these compounds between medicated and unmedicated people with Parkinson’s, although previous studies have identified a particular chemical associated with L-dopa, which would otherwise make interpretations of these results difficult: it would call into question whether the identified compounds are a product of a drug given for Parkinson’s rather than Parkinson’s itself. They did find one chemical, mandelic acid, in the samples of controls and drug naïve people with Parkinson’s, which is associated with neurotransmitter metabolism and could indicate changes seen in Parkinson’s.
Having identified these compounds, they will now have to be validated in a new, larger sample of people with Parkinson’s and controls. The next step will then be to identify what processes lead to these differences and changes.
Original article: Discovery of Volatile Biomarkers of Parkinson’s Disease from Sebum, ACS Central Science: March 20, 2019. Trivedi, DK, Sinclair, E, Xu, Y, Sarkar, D, Walton-Doyle, C, Liscio, C, Banks, P, Milne, J, Silverdale, M, Kunath, T, Goodacre, R, Barran, P.