Investigation Of Air Pollutants In Zhejiang Province And Prospective Study On The Risk Of Alzheimer’s Disease

Background and objective:Along with the continuous improvement of the urbanization level and industrialization degree,the environmental pollution problem caused by it has been highlighted day by day.At present,China has become one of the countries with the most serious air pollution.When the pollution substance in the atmosphere exceeds a certain concentration,it will have harmful effects on the ecosystem and human health.In recent years,there has been a growing body of research linking air pollution to Alzheimer’s disease（AD）.Alzheimer’s disease with memory disorders,apraxia and agnosia as the main manifestations,seriously affect patients’ability to daily life,and even mental behavior abnormalities,bring a great burden to the family and society.With the increasing aging process,the number of people with Alzheimer’s disease is increasing,and Alzheimer’s disease will become one of the most serious health problems in the old people.Therefore,it is of great public health significance and social value to scientifically evaluate air pollution,clarify the relationship between it and the occurrence and development of Alzheimer’s disease,and formulate reasonable and effective preventive measures to prevent the occurrence or delay the development of AD.Based on the data of air quality monitoring stations in Zhejiang Province in 2014,this study mastered the atmospheric pollutant exposure of community residents in Zhejiang Province through empirical Bayesian Kriging spatial interpolation method.Combined with the health monitoring cohort data of the elderly in Zhejiang Province,the incidence of cognitive dysfunction and Alzheimer’s disease among the elderly in Zhejiang Province was understood,and the impact of major air pollution such as PM₁₀,PM_2.5,NO₂,O₃and SO₂on the risk of Alzheimer’s disease among the elderly population was clarified.Method:1.Objects of study:The method of multi-stage stratified cluster sampling was adopted to select a total of 11 counties and districts in Zhejiang Province according to the geographical distribution,counties and villages.10982 eligible elderly people aged 60 and above in 248 villages were selected as the objects of this study.2.Air pollutant exposure assessment:Based on the data of air quality monitoring stations in Zhejiang Province,the empirical Bayesian Kriging spatial interpolation method was used to carry out spatial interpolation of air pollutant concentration in Zhejiang Province,so as to obtain high spatial resolution pollutant exposure levels of each rural point.3.Screening for cognitive dysfunction and diagnosis of Alzheimer’s disease:During follow-up,the Simple Mental State Examination Scale（MMSE）was used to assess cognitive function,and patients with abnormal cognitive function screening were diagnosed with dementia according to the standards of the Mental Disorders and Statistical Manual（DSM-IV）of the American Association for Mental Disorders.Alzheimer’s disease was diagnosed according to the criteria of the American Academy of Neurology,Speech Disorders and Stroke-Alzheimer’s and Related Disorders（NINCDS-ADRDA）.4.Baseline survey and follow-up study:The baseline survey was started in 2014,and the self-designed"Zhejiang Elderly Health Monitoring Project Questionnaire"was adopted to collect the baseline data of each subject.The follow-up survey started at the time of inclusion in the cohort and completion of the questionnaire,with an interval of 1 year and a termination time of December 31,2021.The follow-up survey was based on the baseline survey,and the AD diagnosis was carried out for those with abnormal cognitive function screening during the follow-up,and the follow-up was continued for those with normal cognitive function screening and those without AD diagnosis.5.Statistical analysis:SPSS26.0 software was used for analysis,and Pearson Chi-square test or non-parametric test was used for comparison of basic features.The t test was used to compare the differences of air pollutants between Alzheimer’s disease and normal group.Using the number of years of follow-up as the time scale,Cox proportional hazard regression model was used to calculate the hazard ratio（HR）and 95%confidence interval（CI）of each variable to measure the association between air pollutants and cognitive dysfunction and the incidence of Alzheimer’s disease before and after adjustment for confounding（model covariates were selected by stepwise regression）.Results:A total of 10982 subjects were included in the study.During the 7-year follow-up period,1350 cases of new cognitive dysfunction were collected,with a cumulative incidence of 12.29%,and 971 cases of Alzheimer’s disease,with a cumulative incidence of 8.84%.The total number of follow-up years of all subjects was 38,647person-years,and the incidence density was 25.24/1000 person-years.The outcome rate from cognitive dysfunction to Alzheimer’s disease was about 71.92%.Multivariate Cox regression analysis showed that SO₂,PM₁₀and PM_2.5increased the risk of Alzheimer’s disease among the six air pollutants after adjusting for the mixed factors,and the risk of Alzheimer’s disease increased by 11%for every 1μg/m3 increase of SO₂（HR=1.11,95%CI=1.08--1.12）.For every 1μg/m3 increase in PM₁₀,the risk of Alzheimer’s disease increased by 8%（HR=1.08,95%CI=1.05-1.09）.The risk of Alzheimer’s disease increased by 30%for every 1μg/m3 increase in PM_2.5（HR=1.30,95%CI=1.02-1.65）.O₃is not associated with the occurrence of Alzheimer’s disease.Conclusion:1.The concentrations of NO₂,PM₁₀,O₃and PM_2.5in Zhejiang Province significantly exceed the atmospheric pollutant standards provided by the WHO Air Quality Guidelines in 2021,especially the excessive levels of PM₁₀and PM_2.5.Therefore,corresponding policies should be formulated to control air pollution emission;2.SO₂,PM₁₀and PM_2.5can increase the risk of cognitive dysfunction and are also risk factors for AD.