Occupational exposure to electromagnetic fields and risk of Alzheimer's disease.
BACKGROUND
Extremely-low-frequency magnetic field (ELF-MF) exposure is suspected to increase the risk of Alzheimer's disease. Such fields are present in the vicinity of electrical motors and other electric appliances containing coils.


METHODS
We investigated lifetime occupational ELF-MF exposure in relation to Alzheimer's disease and dementia among a community dementia-free cohort (n = 931) age 75 years and older in Stockholm, Sweden. This cohort was followed from 1987-1989 until 1994-1996 to detect dementia cases (Diagnostic and Statistical Manual of Mental Disorders, revised 3rd edition criteria). Information on lifetime job history was obtained by interview, usually of next of kin. ELF-MF exposure was assessed using a job-exposure matrix, measurement on historical equipment, and expert estimation. We analyzed the data with Cox models controlling for potential confounders.


RESULTS
Dementia was diagnosed in 265 subjects, including 202 with Alzheimer's disease. Among men, ELF-MF exposure > or=0.2 microT in lifetime principal job was related to multivariate-adjusted relative risks of 2.3 (95% CI = 1.0-5.1) for Alzheimer's disease and 2.0 (1.1-3.7) for dementia. We found no association among women. A similar sex-specific pattern was seen for the associations with average ELF-MF exposure throughout the work life. A dose-response relation was suggested in men, with multivariate-adjusted relative risks of 2.4 (0.8-6.8) for Alzheimer's disease and 2.5 (1.1-5.6) for dementia for the upper tertile of lifetime average exposure.


CONCLUSIONS
Long-term occupational exposure to a higher ELF-MF level may increase the risk of Alzheimer's disease and dementia in men. Similar patterns were not seen in women, which may in part be the result of a greater exposure misclassification in women than in men.
Aging Research Center, Division of Geriatric Epidemiology and Medicine, Department of Neurotec, Karolinska Institutet, S-113 82 Stockholm, Sweden. chengxuan.qiu@neurotec.ki.se
Chengxuan
C
Qiu
Laura
L
Fratiglioni
Anita
A
Karp
Bengt
B
Winblad
Tom
T
Bellander
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology / Q000209:etiology*; D015331:Cohort Studies; D003704:Dementia / Q000453:epidemiology / Q000209:etiology*; D004574:Electromagnetic Fields; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D016273:Occupational Exposure / Q000009:adverse effects* / Q000706:statistics & numerical data; D012307:Risk Factors; D012919:Social Behavior; D012959:Socioeconomic Factors; D013548:Sweden / Q000453:epidemiology