What does Parkinson’s disease smell like?

The scent of skin could be used as an early diagnostic tool for Parkinson’s disease. New research by the University of Manchester has found that individuals with Parkinson’s produce a unique smell that can be used to diagnose the condition.

Sebum is a waxy lipid-based compound that is secreted by the skin. It has antimicrobial properties, both pro- and anti-inflammatory activity, and it also delivers anti-oxidants to the surface of skin. Research, funded by Parkinson’s UK and the Michael J. Fox Foundation, has identified specific compounds within sebum that are unique to Parkinson’s patients. If these compounds are detected in abundance, it not only indicates the presence of Parkinson’s disease but also the stage it has progressed to.

Joy Milne, now an Honorary Lecturer at The University of Manchester, inspired this research by her ability to detect changes in her husband’s smell 12 years before he was diagnosed with the Parkinson’s. After realising the scent and disease were connected, she approached researchers and has been working alongside them for three years since.

Gauze was used to swab the upper backs of over 60 subjects, some of whom had Parkinson’s and others did not. The chemical makeup of their sebum was then analysed and verified by Joy Milne, who has been credited in the research paper. Mass spectrometry revealed that the unique odour Joy Milne detects is produced by abnormal levels of hippuric acid, eicosane, and octadecanal. These compounds correspond to neurotransmitter levels, implying that they too have been altered further solidifying the validity of this research as Parkinson’s is a neurodegenerative disorder.

Researchers are therefore hopeful that knowledge of smell’s molecular basis could form an early detection system and thus enable people to access treatment and preventative interventions sooner. Currently, no definitive diagnostic tests are available for Parkinson’s. This makes identification of the disease challenging. Further complications are posed by the fact that the main symptoms (involuntary tremors, slowed movement, and inflexible muscles) are common to other conditions. Additionally, Parkinson’s patients can experience psychological symptoms such as depression, anxiety, insomnia, and memory deterioration.

One in 500 people suffer from this disease and yet the road to diagnosis and treatment is rocky, making new research vital. It is for this reason that this research in Manchester has evoked such excitement. It could isolate the disease years earlier than current methods and even allow for the effectiveness of therapies to be monitored.

Professor David Dexter, Deputy Director of Research at Parkinson’s UK, is keen to stress that further research is needed before skin tests can be used to definitively diagnose the disease. Future research is also needed to establish whether sebum alterations are present in related conditions however this small scale study may have shone light on a whole new field of Parkinson’s diagnostics.