Environmental risk factors for dementia: a systematic review

2016 · Mixed · Moderate evidence

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MixedModerate evidencePaper 1434

The review found mixed evidence regarding low and extremely low frequency electric and magnetic fields and dementia risk, with some studies suggesting an association such as increased Alzheimer's disease mortality for those living near power lines over 15 yea…

Study snapshot

Publicationmanual · 2016

Study typesystematic_review

Reported directionMixed

Evidence ratingModerate

Abstract

- Environmental risk factors for dementia: a systematic review Lewis O. J. Killin, John M. Starr, Ivy J. Shiue, Tom C. Russ. Environmental risk factors for dementia: a systematic review. BMC Geriatrics. DOI: 10.1186/s12877-016-0342-y. Published: 12 October 2016 Abstract Background Dementia risk reduction is a major and growing public health priority. While certain modifiable risk factors for dementia have been identified, there remains a substantial proportion of unexplained risk. There is evidence that environmental risk factors may explain some of this risk. Thus, we present the first comprehensive systematic review of environmental risk factors for dementia. Methods We searched the PubMed and Web of Science databases from their inception to January 2016, bibliographies of review articles, and articles related to publically available environmental data. Articles were included if they examined the association between an environmental risk factor and dementia. Studies with another outcome (for example, cognition), a physiological measure of the exposure, case studies, animal studies, and studies of nutrition were excluded. Data were extracted from individual studies which were, in turn, appraised for methodological quality. The strength and consistency of the overall evidence for each risk factor identified was assessed. Results We screened 4784 studies and included 60 in the review. Risk factors were considered in six categories: air quality, toxic heavy metals, other metals, other trace elements, occupational-related exposures, and miscellaneous environmental factors. Few studies took a life course approach. There is at least moderate evidence implicating the following risk factors: air pollution; aluminium; silicon; selenium; pesticides; vitamin D deficiency; and electric and magnetic fields. Conclusions Studies varied widely in size and quality and therefore we must be circumspect in our conclusions. Nevertheless, this extensive review suggests that future research could focus on a short list of environmental risk factors for dementia. Furthermore, further robust, longitudinal studies with repeated measures of environmental exposures are required to confirm these associations. Excerpt: Two systematic reviews examined low and extremely low frequency electric and magnetic fields and, while the evidence is mixed, there seems to be an association with dementia risk and this was corroborated by a prospective study in Switzerland which found that living close to power lines for over 15 years was associated with a doubling of Alzheimer's disease mortality (but not the occupational study mentioned above [63]) [73, 74]. Its findings are difficult to interpret, but a prospective study in Denmark found that mobile phone subscription was associated with a decreased risk of subsequent hospital admission with dementia [75]. bmcgeriatr.biomedcentral.com

Machine Enhanced Logic

AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typesystematic_review

Effect directionmixed

PopulationNot supplied

Sample size60

Exposureover 15 years (power lines)

Evidence strengthModerateConfidence: 60% · Peer reviewed: yes

Main findings

Outcomes measured

dementia
Alzheimer's disease mortality
hospital admission with dementia

Limitations

Studies varied widely in size and quality
Few studies took a life course approach
Findings are difficult to interpret
Need for further robust, longitudinal studies with repeated exposure measures

View raw extracted JSON

{
  "study_type": "systematic_review",
  "exposure": {
    "band": null,
    "source": "power lines, mobile phone",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "over 15 years (power lines)"
  },
  "population": null,
  "sample_size": 60,
  "outcomes": [
    "dementia",
    "Alzheimer's disease mortality",
    "hospital admission with dementia"
  ],
  "main_findings": "The review found mixed evidence regarding low and extremely low frequency electric and magnetic fields and dementia risk, with some studies suggesting an association such as increased Alzheimer's disease mortality for those living near power lines over 15 years, while a study found mobile phone subscription associated with decreased dementia hospital admissions.",
  "effect_direction": "mixed",
  "limitations": [
    "Studies varied widely in size and quality",
    "Few studies took a life course approach",
    "Findings are difficult to interpret",
    "Need for further robust, longitudinal studies with repeated exposure measures"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.6,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "dementia",
    "environmental risk factors",
    "electric and magnetic fields",
    "power lines",
    "mobile phone",
    "Alzheimer's disease"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.7,
      "reason": "Includes occupational-related exposures and environmental EMF exposure"
    },
    {
      "slug": "5g-policy",
      "weight": 0.5,
      "reason": "Discusses mobile phone use 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: 10.1186/s12877-016-0342-y
PubMed: Not supplied

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