title: Traffic-Related Air Pollution and Dementia Incidence in Northern Sweden: A Longitudinal Study.
abstract: BACKGROUND
  Exposure to ambient air pollution is suspected to cause cognitive effects, but a prospective cohort is needed to study exposure to air pollution at the home address and the incidence of dementia.
  
  
  OBJECTIVE
  We aimed to assess the association between long-term exposure to traffic-related air pollution and dementia incidence in a major city in northern Sweden.
  
  
  METHODS
  Data on dementia incidence over a 15-year period were obtained from the longitudinal Betula study. Traffic air pollution exposure was assessed using a land-use regression model with a spatial resolution of 50 m × 50 m. Annual mean nitrogen oxide levels at the residential address of the participants at baseline (the start of follow-up) were used as markers for long-term exposure to air pollution.
  
  
  RESULTS
  Out of 1,806 participants at baseline, 191 were diagnosed with Alzheimer's disease during follow-up, and 111 were diagnosed with vascular dementia. Participants in the group with the highest exposure were more likely than those in the group with the lowest exposure to be diagnosed with dementia (Alzheimer's disease or vascular dementia), with a hazard ratio (HR) of 1.43 (95% CI: 0.998, 2.05 for the highest vs. the lowest quartile). The estimates were similar for Alzheimer's disease (HR 1.38) and vascular dementia (HR 1.47). The HR for dementia associated with the third quartile versus the lowest quartile was 1.48 (95% CI: 1.03, 2.11). A subanalysis that excluded a younger sample that had been retested after only 5 years of follow-up suggested stronger associations with exposure than were present in the full cohort (HR = 1.71; 95% CI: 1.08, 2.73 for the highest vs. the lowest quartile).
  
  
  CONCLUSIONS
  If the associations we observed are causal, then air pollution from traffic might be an important risk factor for vascular dementia and Alzheimer's disease.
authors: Occupational and Environmental Medicine, Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
authors: Anna
authors: A
authors: Oudin
authors: Bertil
authors: B
authors: Forsberg
authors: Annelie Nordin
authors: AN
authors: Adolfsson
authors: Nina
authors: N
authors: Lind
authors: Lars
authors: L
authors: Modig
authors: Maria
authors: M
authors: Nordin
authors: Steven
authors: S
authors: Nordin
authors: Rolf
authors: R
authors: Adolfsson
authors: Lars-Göran
authors: LG
authors: Nilsson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity; D000397:Air Pollution / Q000009:adverse effects*; D000544:Alzheimer Disease / Q000453:epidemiology* / Q000209:etiology; D002947:Cities / Q000453:epidemiology; D015140:Dementia, Vascular / Q000453:epidemiology* / Q000209:etiology; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009589:Nitrogen Oxides / Q000032:analysis; D011446:Prospective Studies; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D001335:Vehicle Emissions / Q000032:analysis* / Q000633:toxicity
chemical_list: D000393:Air Pollutants; D009589:Nitrogen Oxides; D001335:Vehicle Emissions