At present, cognitive impairment has become a significant threat to the health and quality of life of the elderly population, bringing a huge burden to families and society. Air pollution is the latest confirmed modifiable risk factor for dementia. Previous observational studies have shown a correlation between long-term exposure to fine particulate matter (such as PM2.5) and the occurrence and development of cognitive impairment, dementia, and other neurological disorders.
Previously, a team from the Health and Aging Development Research Center of the National Development Research Institute of Peking University published important research findings in the Lancet Aging Health journal, stating that improving air quality can delay the decline of the elderly population. For this reason, scientists from the United States studied whether the improvement in air quality is related to the slower rate of cognitive decline in elderly women aged 74 to 92, and the results were published in the PLOS MEDICINE journal.
Researchers studied a cohort of 2232 women residing in 48 contiguous states in the United States. They did not have dementia on the baseline from 2008 to 2012. The measurement of cognitive function for the year (2008-2018) includes TICSM and CVLT. Use a regionalized universal Kriging model to estimate the annual concentrations of PM2.5 and NO2 in residential areas. Use a linear mixed effects model to study the relationship between air quality improvement and cognitive decline rates of TICSM and CVLT trajectories.
For PM2.5 and NO2, there was a significant improvement in air quality in the 10 years prior to the inclusion of WHIMS-ECHO. During a median follow-up period of 6.2 years (IQR=5.0), a general cognitive state was observed( β=- 0.42/year, 95% CI: -0.44, -0.40) and explicit memory( β=- 0.59/year, 95% CI: -0.64, -0.54) all showed a decrease.
Overall, the greater improvement in air quality is related to the rate of decline of TICSm( β PM2.5 improvement=0.026/year, with each IQR of PM2.5 improvement=1.79 μ G/m3 reduction, 95% CI: 0.001, 0.05; β NO2 improvement=0.034/year, each IQR of NO2 improvement=392 parts per million [ppb] reduction, 95% CI: 0 01, 0.06) and CVLT( β PM2.5 improvement=0.070/year, per IQR=1.79 μ G/m3 reduction, 95% CI: 0.02, 0.12; β NO2 improvement=0.060/year, decrease per IQR=3.97 ppb, 95% CI: 0.005, 0.12).
The respective associations with TICSm and CVLT are equivalent to the slower decline rates observed at ages 0.9 to 1.2 and 1.4 to 1.6, and there are no significant differences in age, region, education, ApoE e4 genotype, or cardiovascular risk factors.
In summary, the greater improvement in long-term air quality in later years is related to the slower decline in cognitive abilities of elderly women. This new observation strengthens the epidemiological evidence between air pollution and cognitive aging.
