Belvisi D, Pellicciari R, Fabbrini A, et al. - In this large case-control study, researchers sought to perform a simultaneous evaluation of potential risk/protective factors of Parkinson disease (PD) to identify independent risk/protective factors, to evaluate interaction among factors, and to ascertain if identified risk factors predict etiologic subtypes of PD. The simultaneous assessment of 31 putative risk/protective factors of PD demonstrated that only coffee consumption, smoking, physical activity, family history of PD, dyspepsia, and exposure to pesticides, oils, metals, and general anesthesia were independently linked to PD. This investigation showed that 9 factors independently modify PD risk by coexisting in the same patient rather than interacting with others. The research indicates the need for potential preventive measures aimed at minimising the coexistence within the same participant of various risk factors.