Dementia and occupational exposure to magnetic fields

Objectives The purpose of the present report was to assess whether occupational magnetic field exposure is a risk factor for dementia, in particular for Alzheimer's disease. Methods Case-control analyses were applied to 77 dementia cases, 55 of whom had Alzheimer's disease, ascertained from the population-based Swedish twin register. Two reference groups were derived, with 228 and 238 persons, respectively. Occupations were linked to a job-exposure matrix based on magnetic field measurements. Primary occupation, last occupation before reference date, and the occupation with the highest magnetic field exposure during the subject's lifetime were evaluated. Results For primary occupation, all relative risk estimates were close to unity. For last occupation, at the exposure level greater than or equal to 0.2 mu T, a relative risk was found for dementia estimated at 3.3 [95% confidence interval (95% CI) 1.3-8.6] and 3.8 (95% CI 1.4-10.2) for reference groups 1 and 2, respectively. The relative risk for Alzheimer's disease was estimated at 2.4 (95% CI 0.8-6.9) and 2.7 (95% CI 0.9-7.8), respectively. For the occupation with the highest magnetic field exposure, the relative risk estimates were close to unity for reference group 1 and slightly elevated for reference group 2. The relative risk estimates were greater for the subjects who were younger at onset (less than or equal to 75 years). Conclusions These results only partially support previous findings, but they indicate that occupational magnetic field exposure may possibly influence the development of dementia.