Residential distance from high-voltage overhead power lines and risk of Alzheimer's dementia and Parkinson's disease: a population-based case-control study in a metropolitan area of Northern Italy

Background: The association between the extremely low-frequency magnetic field generated by overhead power lines and neurodegenerative disease is still amatter of debate. Methods: A population-based case-control study was carried out on the residents in the Milan metropolitan area between 2011 and 2016 to evaluate the possible association between exposure to extremely low-frequency magnetic fields generated by high-voltage overhead power lines and Alzheimer's dementia and Parkinson's disease. A statistical analysis was performed on cases and controls matched by sex, year of birth and municipality of residence (with a case to controls ratio of 1 : 4) using conditional logistic regression models adjusted for socio-economic deprivation and distance from the major road network as potential confounders. Results: Odds ratios for residents <50 m from the source of exposure compared with residents at >= 600 m turned out to be 1.11 (95% confidence interval: 0.95-1.30) for Alzheimer's dementia and 1.09 (95% confidence interval: 0.92-1.30) for Parkinson's disease. Conclusions: The finding of a weak association between exposure to the extremely low-frequency magnetic field and neurodegenerative diseases suggests the continuation of research on this topic. Moreover, the low consistency between the results of the already existing studies emphasises the importance of increasingly refined study designs.