Occupational risk factors in Parkinson's disease

Background: An apparent excess of teachers and healthcare workers among the Parkinson's disease patients of a large tertiary care movement disorders clinic suggested the hypothesis that high exposure to viral (or other) respiratory infections in these occupations might be a risk factor for Parkinson's disease. Methods: A case-control study of the association between occupation and Parkinson's disease was conducted. Cases (414) were all Parkinson's disease patients seen at the University of British Columbia Hospital Movement Disorders Clinic between 1986 and 1933, residing in Greater Vancouver, and under 65 in 1991. Controls (6,659) were randomly selected from the 1991 Canadian Census. Findings: Parkinson's disease was associated with teaching (OR 2.50, 95% CI 1.67-3.74) and occupation in healthcare services (OR 2.07, 95% CI 1.34-3.20), but there were several other substantial associations, both positive and negative. Interpretation: While referral bias cannot be ruled our, the authors find the consistency of the overall pattern of associations with the respiratory infection hypothesis striking.