HealthDay News — Greater improvement in long-term air quality (AQ) in late life is associated with slower cognitive declines in older women, according to a study published online Feb. 3 in PLOS Medicine.

Diana Younan, Ph.D., M.P.H., from University of Southern California in Los Angeles, and colleagues examined whether AQ improvement was associated with slower rates of cognitive decline in older women (aged 74 to 92 years). The analysis included 2,232 U.S. women enrolled in the Women’s Health Initiative Memory Study-Epidemiology of Cognitive Health Outcomes study who were dementia free at baseline (2008 to 2012).

The researchers found that during a median 6.2 years of follow-up, there were declines in both general cognitive status (β = −0.42/year) and episodic memory (β = −0.59/year). When adjusting for covariates, there was an association seen between greater AQ improvement and slower decline in the modified Telephone Interview for Cognitive Status (TICSm) scores (βPM2.5improvement = 0.026 per year for improved fine particulate matter [PM2.5] by each interquartile range = 1.79 μg/m3 reduction; βNO2improvement = 0.034 per year for improved nitrogen dioxide [NO2] by each interquartile range = 3.92 parts per billion reduction) and the California Verbal Learning Test (CVLT; βPM2.5improvement = 0.070 per year for improved PM2.5 by each interquartile range = 1.79 μg/m3 reduction; βNO2improvement = 0.060 per year for improved NO2 by each interquartile range = 3.97 parts per billion reduction). The respective associations with TICSm and CVLT were similar to the slower decline rate seen with 0.9 to 1.2 and 1.4 to 1.6 years of younger age. There were no significant differences observed by age, region, education, apolipoprotein E e4 genotypes, or cardiovascular risk factors.

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“The underlying neurobiological processes driving the observed slower cognitive declines associated with improved AQ are unclear,” the authors write.

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