Occupational exposure to low frequency magnetic fields and dementia: a case-control study.

BACKGROUND

Several studies point to a potential aetiological relevance to dementia of exposure to low-frequency magnetic fields, but the evidence is inconclusive.

OBJECTIVE

To further examine the relationship between low frequency magnetic fields and dementia.

METHODS

From 23 general practices, 195 patients with dementia were recruited. Of these, 108 had possible Alzheimer's disease, 59 had possible vascular dementia and 28 had secondary or unclassified dementia. A total of 229 controls were recruited: 122 population controls and 107 ambulatory patients free from dementia. Data were gathered in a structured personal interview; in cases, the interview was administered to the next of kin. Exposure to low-frequency electromagnetic fields was assessed by expert rating. To identify occupations suspected to be associated with dementia, major occupations were a priori formed. Odds ratios were calculated using logistic regression, to control for age, region, sex, dementia in parents and smoking.

RESULTS

Exposure to magnetic fields was not significantly associated with dementia; restriction of the analysis to cases with possible Alzheimer's disease or possible vascular dementia did not lead to statistically significant results. We found an increased risk of dementia in blue-collar occupations (electrical and electronics workers, metal workers, construction workers, food and beverage processors and labourers).

CONCLUSIONS

Our study does not support a strong association between occupational exposure to low-frequency magnetic fields and dementia. Further studies should consider the relationship between blue-collar work and the late development of dementia.