Can Parkinson’s disease (PD) be detected before symptoms start, from just a skin swab?
A new study from the University of Manchester found that volatile organic compounds (VOCs) in skin sebum can help identify PD up to seven years before motor symptoms appear.
The findings, published in npj Parkinson’s Disease, suggest that a low-cost, non-invasive tool for early diagnosis and monitoring may be possible.
Why early Parkinson’s detection needs better tools
PD affects over 10 million people globally, a number that is expected to double in the next generation. Diagnosis is based on motor symptoms such as tremor and rigidity, which do not show up until the disease has already progressed. This delay makes it hard to intervene early or assess potential treatments.
There’s strong interest in finding early, low-cost and non-invasive tests. One early sign of PD is isolated REM Sleep Behaviour Disorder (iRBD), which causes people to physically act out dreams during sleep. Around 80–90% of people with iRBD go on to develop a neurodegenerative disease, usually PD.
Previous research from the same team found that PD is linked to a specific smell, strongest in oily areas of the skin. The team discovered sebum – the waxy substance the skin produces – contains chemical compounds (i.e., VOCs) that differ in people with PD. These VOCs can be analysed in the lab.
Volatile organic compounds (VOCs)
VOCs are chemicals that easily evaporate at room temperature. In the body, they can be released through breath, sweat, urine or skin oils such as sebum.
Until now, no study had tested whether the VOCs in sebum could detect PD before symptoms begin, and whether they could be used as markers of early-stage PD.
“Our goal is to develop a reliable, non-invasive test that helps doctors detect Parkinson’s earlier, track its progression and ultimately improve patient outcomes,” said senior author Dr. Drupad Trivedi, a lecturer in analytical measurement sciences at the University of Manchester.
Skin swabs show promise for Parkinson’s detection
The study involved 83 people: 46 with PD, 28 healthy controls and 9 with iRBD. Within the PD group, 11 were followed for 3 years to track changes over time.
Trivedi and the team collected skin swabs from the upper back, a sebum-rich area, and analyzed them to detect VOCs using a method called thermal desorption gas chromatography-mass spectrometry (TD-GC-MS).
They found 613 VOC features across the samples. Statistical modelling separated the PD, iRBD and control groups based on their skin chemical profiles.
In total, 55 features showed a pattern where levels in the iRBD group sat between those of the controls and the Parkinson’s group, suggesting they may be progression markers – molecules that change as the disease develops.
When comparing people with Parkinson’s to controls, 85 VOCs stood out, many of which were linked to fatty compounds in the skin. Again, the team observed that the iRBD samples were chemically between the groups
In the longitudinal group, 38 VOCs changed over time, which suggests that these new markers may emerge as the disease progresses. Age, sex, BMI and medication didn’t explain these differences.
A skin swab could help detect Parkinson’s years earlier
The research was inspired by Joy Milne, a retired nurse with a remarkably strong sense of smell. She noticed a distinct scent on her husband years before he was diagnosed with Parkinson’s, and this observation led researchers to investigate sebum.
During the study, Milne was able to pick out several iRBD samples as having a distinct smell. Two of those people were later diagnosed with PD.
“This is the first study to demonstrate a molecular diagnostic method for PD at the prodromal or early stage,” said co-author Dr. Perdita Barran, a professor of MS at the University of Manchester. “It brings us one step closer to a future where a simple, non-invasive skin swab could help identify people at risk before symptoms arise, allowing for earlier intervention and improved outcomes.”
The results suggest that earlier diagnosis might be possible – potentially up to seven years sooner than current methods. It could also allow routine screening of high-risk groups, such as people with iRBD, and help track how the disease changes over time in individual patients.
The test is simple and low-cost, since sebum can be collected easily with a gauze swab, doesn’t need cold storage and can be mailed in from home.
In a parallel study published in the Journal of Parkinson’s Disease, trained dogs were also able to detect PD by sniffing skin swabs collected by the team. Their accuracy matched the chemical analysis, further supporting the idea that Parkinson’s measurably alters the smell of sebum.
The researchers stress that more work is needed. The iRBD sample was small, and larger, more diverse studies are needed to confirm these results. Current technology also limits how precisely some molecules can be identified.
Next steps for the team include refining the test, expanding the cohort and developing a diagnostic tool that can be used in clinics.
“We’re also keen to hear from other hyperosmic individuals, potential ‘super smellers’ like Joy, whose remarkable sense of smell could help extend our work to detect other diseases with potential odour signatures,” added Trivedi.
Reference: Walton-Doyle C, Heim B, Sinclair E, et al. Classification of Parkinson’s disease and isolated REM sleep behaviour disorder: delineating progression markers from the sebum volatilome. npj Parkinsons Dis. 2025;11(1). doi: 10.1038/s41531-025-01026-8
This article is a rework of a press release issued by the University of Manchester. Material has been edited for length and content.