Objective: To evaluate the association between pesticide exposure and development of Parkinson’s disease (PD) in idiopathic and genetic PD, and to determine whether clinical features of PD in patients exposed to pesticides differ from people without.

Background: Many studies show an association between pesticide exposure and PD development, though how genetic risk variants modify these associations are still unclear. Additionally, the clinical features of PD are very different between patients, and the cause of this variability is not well understood.

Method: Participants in the Parkinson’s Progression Markers Initiative (PPMI) and Fox Insight (FI) cohorts provided information via an online survey about environmental risk factors. Phenotype was determined using MDS-UPDRS and MoCA scores in PPMI and baseline self-reported cognitive impairment (SCI) in FI.  We separated participants into idiopathic PD (iPD) or PD with a risk variant (either GBA or LRRK2). We used parametric and non-parametric tests as appropriate, adjusting for age and sex, as well as depression for SCI. We hypothesized that pesticide exposure would increase the risk of PD and be associated with a more severe phenotype.

Results: Responses were provided by 741 PPMI and 2,868 FI participants. In PPMI, occupational exposure to pesticide use was associated with a higher risk of developing idiopathic PD (adjusted OR = 3.90, 95% CI = 1.27 – 17.1, p = 0.034) though home exposure was not (aOR = 1.06, 95% CI = 0.525 – 2.07, p = 0.879). Among people with a GBA risk variant, pesticide exposure was associated with a higher risk of PD (aOR = 4.19, 95% CI = 1.09 – 18.4, p=0.047). This risk was still elevated but not significant in those with a LRRK2 variant (aOR = 1.38, 95% CI = 0.375 – 5.118, p = 0.62). In participants with idiopathic PD, there was a trend towards greater cognitive decline among those exposed to pesticides (MoCA change -1.44 vs + 0.299, p = 0.059). In FI, pesticides were associated with an increased risk of PD (aOR = 1.44, 95% CI = 1.01 – 2.12, p = 0.052). SCI was more likely in patients with a history of pesticide exposure (aOR = 1.51, 95% CI = 1.22 – 1.87, p < 0.001).

Conclusion: Pesticide use may increase the risk of PD in idiopathic and GBA-PD, and may also increase the risk of cognitive decline once PD develops.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/pesticide-exposure-in-pd-with-and-without-genetic-risk-variants/