Differences in the serum lipidome and metabolome were observed, partially matching previously published works. However, most of the chemicals found in dust, which may be potential risks for human health, were not found in the serum samples. This may be because exogenous chemicals are present at trace levels in biological samples compared with endogenous chemicals . Importantly, some of the differences observed in both dust and serum may be due to confounding factors. For instance, the use of medication in the PD groups may influence the metabolism (although no clear relationship was found here), while discrepancies in sample size and age between certain groups, may influence the results. The average age of the PD-/LRRK2+ group is ten years younger than PD+/LRRK2+, which means that some patients may still develop PD at a later stage. However, it was not possible to get a better match of ages with the samples available in the cohort at this stage .