Abstract

Objective We investigated associations between Parkinson's disease and other degenerative parkinsonian syndromes and environmental factors in five European countries. Methods We undertook a case-control study of 959 prevalent cases of parkinsonism (767 with Parkinson’s disease) and 1989 controls in Scotland, Italy, Sweden, Romania and Malta. We defined cases using the United Kingdom Parkinson's Disease Society Brain Bank criteria and excluded those with drug-induced or vascular parkinsonism or dementia. Subjects completed an interviewer-administered questionnaire regarding lifetime occupational and hobby exposure to solvents, pesticides, iron, copper and manganese. Lifetime and average annual exposures were estimated blind to disease status using a job-exposure matrix modified by subjective exposure modelling. Results were analysed using multiple logistic regression adjusting for age, sex, tobacco use, ever knocked unconscious and family history of Parkinson's disease. Results Adjusted logistic regression analyses showed significantly increased odds ratios for Parkinson's disease/parkinsonism with an exposure-response relationship for pesticides (low v no exposure, OR 1.13, 95% CI 0.82-1.57, high v no exposure, OR 1.41, 95% CI 1.06-1.88) and ever knocked unconscious (once v never, OR 1.35, 95% CI 1.09-1.68, more than once v never, OR 2.53, 95% CI 1.78-3.59). Hypnotic, anxiolytic or anti-depressant use for more than one year and a family history of Parkinson's disease showed significantly increased odds ratios. Tobacco use was protective (OR 0.50, 95%CI 0.42-0.60). Analyses confined to subjects with Parkinson’s disease gave similar results. Conclusions The association of pesticide exposure with Parkinson’s disease suggests a causative role. Repeated traumatic loss of consciousness is associated with increased risk.