Objective: To examine the pattern of ligand uptake on F-DOPA PET in patients with PD who were exposed or not exposed to pesticides and examine whether patients exposed to pesticides had less asymmetry in ligand uptake compared to matched PD non-exposed patients.

Background: Susceptibility to Parkinson’s disease (PD) is believed to involve an interaction between genetic and environmental factors. The role of pesticides as a risk factor of PD and neurodegeneration remains controversial. An asymmetric decrease in ligand uptake on F-DOPA positron emission tomography (PET), especially in the dorsal putamen, is a sensitive marker of PD. There is no data regarding F-DOPA uptake in healthy individuals or in patients with PD years after exposure to pesticides.

Methods: The cohort included 13 patients with PD who were exposed to pesticides and 13 age- and disease duration-matched non-exposed PD patients. Disease severity was assessed with the Unified PD Rating Scale (UPDRS), and a clinical asymmetry index was calculated based on signs of tremor, rigidity, and bradykinesia. All patients underwent F-DOPA PET imaging, and an asymmetry index of ligand uptake between the ipsilateral and contralateral caudate, putamen, and whole striatum was calculated.

Results: In the 13 patients who had been exposed to pesticides, the mean duration of exposure was 26.3±16.5 years, and the mean time from the last exposure to the emergence of motor symptoms of PD was 14.6±15.6 years. The mean age of the whole sample was 69.1±5.5 years, and the mean duration of PD was 3.3±1.6 years. Most patients (65%) had vascular risk factors. No significant difference was found in the median asymmetry index of the UPDRS scores between the pesticide-exposed and non-exposed groups (5.0 vs 5.0, p=0.15. Striatal-binding indices between the more or less affected sides of the putamen, caudate, and whole striatum did not differ between the exposed and non-exposed groups. There were no significant between-group differences in the asymmetry index in the putamen (p=0.84) and caudate nuclei (p=0.78) or the whole striatum (p=0.45).

Conclusions: Although exposure to pesticides might be a risk factor for PD, it has no effect on the asymmetry pattern of the degenerative process of the nigrostriatal system compared to non-exposure. We assume that once the disease process is initiated in exposed patients, the pathogenic mechanism does not differ from that of idiopathic PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-role-of-exposure-to-pesticides-in-the-etiology-of-parkinsons-disease-f-dopa-positron-emission-tomography-study/