Long-term exposure to PM10 and ozone increases the risk of Alzheimer’s disease and vascular dementia in the elderly There is evidence that exposure to air pollution may induce changes in the brain. In a new study of elderly people living in northern Taiwan, researchers from National Taiwan University found that long-term exposure to airborne particulates and ozone increases the risk of developing Alzheimer’s disease (AD) and small-vessel vascular dementia (VaD) by two to four times. This work has been selected as a Special Invited Article 1 with a featured video 2 and an Invited Commentary 3 for publication in an open access journal of the Alzheimer’s Association, USA. “Only a small portion of cognitively impaired elderly progress to dementia each year; therefore, studies on cognitive impairment have been unable to fully explain the association between exposure to air pollutants and dementia risk,” explained lead investigator Dr. Yen-Ching Chen. “To the best of our knowledge, this is the first case-control study that assessed the association between longitudinal air pollution [particulate matter (PM) and ozone] exposure with clinically diagnosed dementia (AD and VaD).” Currently, there is no cure for dementia, the clarification of association between air pollutants and dementia will be helpful to unravel the complex etiology of dementia. This case-control study comprised 249 AD patients, 125 small-vessel VaD patients, and 497 controls recruited from three teaching hospitals in northern Taiwan from 2007 to 2010. All participants aged 60 or older. “The long-term exposure data is especially important because the progression of dementia is slow, which may not be easily explained by short-term exposure” says Dr. Chen. Therefore, PM <10 μm in diameter (PM10) and ozone data were obtained from the Taiwan Environmental Protection Administration (EPA) for 12 and 14 years respectively. A spatiotemporal tool Bayesian Maximum Entropy was used to estimate the individual exposure level of air pollutants. Long-term exposure to ≥ 49 µg/m3 of PM10 (Taiwan 24-hr standard: 125 μg/m3; annual standard: 65 μg/m3) and ≥ 22 ppb of ozone (Taiwan 8-hr standard: 60 ppb) were significantly associated with 4- and 2-fold risk of AD, respectively. Similar findings were observed for VaD. In addition, this study revealed a dose-response relationship between PM10 and the risk of AD and VaD for the first time. Published paper on air pollution and health outcomes will be considered by EPA for determining standards. “This study found significant increase in dementia risk despite the long-term exposure to air pollutants with levels below current standard. Therefore, it is important to clarify the role of air pollutants on dementia occurrence, and studies evaluating this association have been lacking. Future studies are warranted to explore the role of other air pollutants in the etiology of AD and VaD,” noted Dr. Chen. This study is therefore a crucial starting point for future work on the effect of air pollution and dementia risk. REFERENCES 1.Yun-Chun Wu, Yuan-Chien Lin, Hwa-Lung Yu, Jen-Hau Chen, Ta-Cu Chen, Yu Sun, Li-Li Wen, Ping-Keung Yip, Yi-Min Chu, Yen-Ching Chen. Association between air pollutants and dementia risk in the elderly. Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring 1(2): 220-228 (2015). http://www.dadm.alzdem.com/article/S2352-8729(15)00045-7/fulltex 2.Video: http://www.dadm.alzdem.com 3.Kathleen M. Hayden, Kevin M. Farmer. Invited commentary: The importance of studying environmental risk factors for dementia Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring 1(2): 268-269 (2015). http://www.dadm.alzdem.com/article/S2352-8729(15)00050-0/pdf Associate Professor Yen-Ching Chen Institute of Epidemiology and Preventive Medicine karenchen@ntu.edu.tw Professor Hwa-Lung Yu Department of Bioenvironmental Systems Engineering hlyu@ntu.edu.tw