Classification of Parkinson’s disease and isolated REM sleep behaviour disorder: delineating progression markers from the sebum volatilome

Parkinson’s Disease (PD) has been associated with a distinct odour, emanating from the skin and strongest in sebum-rich areas. Here, volatile components from sebum were analysed directly with Thermal Desorption Gas Chromatography - Mass Spectrometry. We analysed samples from subjects with clinically established PD (n = 46), controls (n = 28) and participants with isolated REM sleep behaviour disorder (iRBD, n = 9) to investigate metabolite changes in probable prodromal PD. We found 55 significant features where abundance from individuals with iRBD was intermediate between PD and control and assigned putative identifications. Olfactory analysis of the iRBD samples showed three classified as PD, of which two displayed PD symptoms on clinical follow-up. Further, we analysed PD participants sampled at yearly intervals and investigated features displaying regulation over the visits. Our findings support the use of sebum as an accessible biofluid, rich with measurable volatile compounds that alter in abundance in individuals with PD and iRBD.