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Work-related exposure to extremely low-frequency magnetic fields and dementia: results from the population-based study of dementia in Swedish twins.

The journals of gerontology. Series A, Biological sciences and medical sciences · 2010 · Mixed · Low evidence

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In the full sample, level of occupational extremely low-frequency magnetic field exposure was not significantly associated with dementia or Alzheimer's disease. In stratified analyses, medium and high exposure (vs low) were associated with increased dementia …

Study snapshot

PublicationThe journals of gerontology. Series A, Biological sciences and medical sciences · 2010
Study typecohort
Reported directionMixed
Evidence ratingLow

Abstract

BACKGROUND: We examined the association between extremely low-frequency magnetic fields (EMF) and the risk of dementia and Alzheimer's disease using all 9,508 individuals from the Study of Dementia in Swedish Twins (HARMONY) with valid occupational and diagnostic data. METHODS: Dementia diagnoses were based on telephone screening followed by in-person clinical workup. Main lifetime occupation was coded according to an established EMF exposure matrix. Covariates were age, gender, education, vascular risk factors, and complexity of work. Based on previous research, data were also analyzed separately for cases with disease onset by age 75 years versus later, men versus women, and those with manual versus nonmanual main occupation. We used generalized estimating equations with the entire sample (to adjust for the inclusion of complete twin pairs) and conditional logistic regression with complete twin pairs only. RESULTS: Level of EMF exposure was not significantly associated with dementia or Alzheimer's disease. However, in stratified analyses, medium and high levels of EMF exposure were associated with increased dementia risk compared with low level in cases with onset by age 75 years (odds ratio: 1.94, 95% confidence interval: 1.07-3.65 for medium, odds ratio: 2.01, 95% confidence interval: 1.10-3.65 for high) and in participants with manual occupations (odds ratio: 1.81, 95% confidence interval: 1.06-3.09 for medium, odds ratio: 1.75, 95% confidence interval: 1.00-3.05 for high). Results with 42 twin pairs discordant for dementia did not reach statistical significance. CONCLUSIONS: Occupational EMF exposure appears relevant primarily to dementia with an earlier onset and among former manual workers.

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AI evidence extraction

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Study typecohort
Effect directionmixed
PopulationSwedish twins in the Study of Dementia in Swedish Twins (HARMONY) with valid occupational and diagnostic data
Sample size9508
ExposureELF · lifetime (main occupation)
Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

In the full sample, level of occupational extremely low-frequency magnetic field exposure was not significantly associated with dementia or Alzheimer's disease. In stratified analyses, medium and high exposure (vs low) were associated with increased dementia risk for cases with onset by age 75 years and among participants with manual occupations; analyses restricted to 42 dementia-discordant twin pairs were not statistically significant.

Outcomes measured

  • Dementia
  • Alzheimer's disease

Limitations

  • Exposure was assigned using an occupational EMF exposure matrix based on main lifetime occupation (not direct measurements).
  • Stratified analyses showed associations while overall analyses did not.
  • Results in the discordant-twin-pair analysis (42 pairs) did not reach statistical significance.
View raw extracted JSON
{
  "study_type": "cohort",
  "exposure": {
    "band": "ELF",
    "source": "occupational",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "lifetime (main occupation)"
  },
  "population": "Swedish twins in the Study of Dementia in Swedish Twins (HARMONY) with valid occupational and diagnostic data",
  "sample_size": 9508,
  "outcomes": [
    "Dementia",
    "Alzheimer's disease"
  ],
  "main_findings": "In the full sample, level of occupational extremely low-frequency magnetic field exposure was not significantly associated with dementia or Alzheimer's disease. In stratified analyses, medium and high exposure (vs low) were associated with increased dementia risk for cases with onset by age 75 years and among participants with manual occupations; analyses restricted to 42 dementia-discordant twin pairs were not statistically significant.",
  "effect_direction": "mixed",
  "limitations": [
    "Exposure was assigned using an occupational EMF exposure matrix based on main lifetime occupation (not direct measurements).",
    "Stratified analyses showed associations while overall analyses did not.",
    "Results in the discordant-twin-pair analysis (42 pairs) did not reach statistical significance."
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "extremely low-frequency",
    "magnetic fields",
    "occupational exposure",
    "dementia",
    "Alzheimer's disease",
    "twins",
    "HARMONY",
    "Sweden"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.95,
      "reason": "Study evaluates work-related (occupational) ELF magnetic field exposure and dementia risk."
    }
  ]
}
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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1093/gerona/glq112
PubMed: 20622138

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