Background: Dietary factors and history of smoking remain elusive in the pathogenesis of Parkinson's disease (PD).
Objective: We investigated the association of environmental factors with PD in a rural population in China.
Methods: Subjects were participants of a past nutritional intervention trial. Information on their characteristics was collected during the baseline interview of the trial. Control subjects were randomly selected from the same cohort and frequency matched for sex, age and residential area.
Results and conclusion: Among 16,488 subjects surveyed, we diagnosed 464 subjects with PD. Then, four sex- and age-matched controls were paired with each definite PD case. A total of 85 cases and 340 controls were analyzed. Meat consumption and the body mass index (BMI) were inversely associated with PD. The PD risk declined with the increment of BMI. A history of gastric ulcer was associated with an increased risk of PD. As to smoking, there seemed an increased risk of PD among individuals who smoked regularly, non-significantly. However, a significantly increased risk of PD was found among those who smoked more than 30 pack-years.