title: Increased risk of dementia in patients exposed to nitrogen dioxide and carbon monoxide: a population-based retrospective cohort study.
abstract: BACKGROUND
  The air pollution caused by vehicular emissions is associated with cognitive decline. However, the associations between the levels of nitrogen dioxide (NO2) and carbon monoxide (CO) exposure and dementia remain poorly defined and have been addressed in only a few previous studies.
  
  
  METHODS
  In this study, we obtained data on 29547 people from the National Health Insurance Research Database (NHIRD) of Taiwan, including data on 1720 patients diagnosed with dementia between 2000 and 2010, and we evaluated the risk of dementia among four levels of air pollutant. Detailed data on daily air pollution were available from January 1, 1998 to December 31, 2010. Yearly average concentrations of pollutants were calculated from the baseline to the date of dementia occurrence, withdrawal of patients, or the end of the study, and these data were categorized into quartiles, with Q1 being the lowest level and Q4 being the highest.
  
  
  RESULTS
  In the case of NO2, the adjusted hazard ratios (HRs) of dementia for all participants in Q2, Q3, and Q4 compared to Q1 were 1.10 (95% confidence interval (CI), 0.96-1.26), 1.01 (95% CI, 0.87-1.17), and 1.54 (95% CI, 1.34-1.77), and in the case of CO, the adjusted HRs were 1.07 (95% CI, 0.92-1.25), 1.37 (95% CI, 1.19-1.58), and 1.61 (95% CI, 1.39-1.85).
  
  
  CONCLUSIONS
  The results of this large retrospective, population-based study indicate that exposure to NO2 and CO is associated with an increased risk of dementia in the Taiwanese population.
authors.affiliation: Department of Public Health, China Medical University, Taichung, Taiwan; Department of Medical Research, Taichung Veterans General Hospital, Taichung, Taiwan.
authors.forename: Kuang-Hsi
authors.initials: KH
authors.lastname: Chang
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, School of Medical and Health Sciences, Fooyin University, Kaohsiung, Taiwan.
authors.forename: Mei-Yin
authors.initials: MY
authors.lastname: Chang
authors.affiliation: Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Chih-Hsin
authors.initials: CH
authors.lastname: Muo
authors.affiliation: Department of Public Health, China Medical University, Taichung, Taiwan.
authors.forename: Trong-Neng
authors.initials: TN
authors.lastname: Wu
authors.affiliation: Department of Public Health, China Medical University, Taichung, Taiwan.
authors.forename: Chiu-Ying
authors.initials: CY
authors.lastname: Chen
authors.affiliation: Graduate Institute of Clinical Medical Science, College of Medicine, China Medical University, Taiwan; Department of Nuclear Medicine and PET Center, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Chia-Hung
authors.initials: CH
authors.lastname: Kao
mesh_terms: D000368:Aged; D000393:Air Pollutants; D000397:Air Pollution / Q000009:adverse effects; D002248:Carbon Monoxide / Q000009:adverse effects*; D015331:Cohort Studies; D016208:Databases, Factual; D003704:Dementia / Q000453:epidemiology* / Q000209:etiology*; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009585:Nitrogen Dioxide / Q000009:adverse effects*; D011159:Population Surveillance; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012306:Risk; D012621:Seasons; D013624:Taiwan / Q000453:epidemiology
chemical_list: D000393:Air Pollutants; D002248:Carbon Monoxide; D009585:Nitrogen Dioxide