Objective: To evaluate whether pesticide exposure is associated with greater baseline motor severity and accelerated longitudinal motor progression in Mexican patients with Parkinson’s disease (PD).

Background: Environmental pesticide exposure has been implicated as a potential risk factor for PD. Experimental studies suggest mechanisms involving oxidative stress, mitochondrial dysfunction, and dopaminergic neuronal loss. However, whether such exposure influences motor severity at presentation or modifies longitudinal motor progression remains uncertain, particularly in Latin American populations.

Method: We conducted a retrospective longitudinal cohort study including 158 patients with clinically diagnosed PD evaluated at a national referral center in Mexico City between 2021 and 2025. Each patient had at least two visits, and 417 longitudinal assessments were analyzed. Pesticide exposure was determined through structured clinical interviews and questionnaires. Motor severity was assessed using the Movement Disorder Society–Unified Parkinson’s Disease Rating Scale part III (MDS-UPDRS III), predominantly in the ON state, using the same scale across visits. Linear mixed-effects models with random intercepts for each patient were used to evaluate the longitudinal association between pesticide exposure and MDS-UPDRS III scores, adjusting for age and sex. An exposure–time interaction term assessed differences in progression. Secondary analyses examined exposure duration, pesticide type, and baseline motor severity using ordinal logistic regression.

Results: In adjusted mixed-effects models, pesticide exposure was not significantly associated with MDS-UPDRS III scores (β = 3.18, p = 0.295). No significant exposure–time interaction was observed (β = −0.57, p = 0.651), indicating similar motor progression between exposed and non-exposed groups. Analyses stratified by years of exposure, pesticide category, and baseline ordinal severity showed consistent non-significant results.

Conclusion: In this retrospective longitudinal cohort of Mexican patients with PD, pesticide exposure was not associated with greater motor severity or accelerated progression. Larger studies with more detailed exposure characterization are warranted.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/pesticide-exposure-and-motor-severity-in-parkinsons-disease-in-a-mexican-population-a-retrospective-longitudinal-cohort-study/