Association between exposure to air pollution and thalamus volume in adults: A cross-sectional study.

BACKGROUND: Air pollution has been associated with cognitive function and brain volume. While most previous research has examined the association between air pollution and brain volume in cortical structures or total brain volume, less research has investigated associations between exposure to air pollution and subcortical structures, including the thalamus. Further, the few available previous studies investigating associations between air pollution and thalamic volume have shown mixed results. METHODS: In this study, we evaluated the association between PM2.5, PM2.5-10, PM10, nitrogen dioxide, and nitrogen oxides and volume of the thalamus in adults using the UK Biobank resource, a large community-based sample, while adjusting for multiple covariates that could confound an association between air pollution and thalamic volume. RESULTS: In adjusted models, the left but not right thalamus volume was significantly inversely associated with PM2.5-10, although there were no significant associations between PM2.5, PM10, nitrogen dioxide, and nitrogen oxides with either left or right thalamic volumes. In addition, interactions between age and PM2.5-10 and PM10 were inversely associated with thalamic volume, such that thalamic volume in older people appeared more vulnerable to the adverse effects of PM2.5-10 and PM10, and interactions between educational attainment and PM2.5, nitrogen dioxide, and nitrogen oxides and between self-rated health and PM2.5-10 were positively associated with thalamic volume, such that higher educational attainment and better self-rated health appeared protective against the adverse effects of air pollution on the thalamus. CONCLUSION: These findings suggest a possible association between thalamic volume and air pollution particularly in older people and in people with comparatively low educational attainment at levels of air pollution found in the United Kingdom.

Association between Exposure to Air Pollution and Total Gray Matter and Total White Matter Volumes in Adults: A Cross-Sectional Study.

Total brain gray-matter and white-matter volumes can be indicators of overall brain health. Among the factors associated with gray-matter and white-matter volumes is exposure to air pollution. Using data from the UK Biobank, we sought to determine associations between several components of air pollution-PM2.5, PM2.5-10, PM10, nitrogen dioxide, and nitrogen oxides-and total gray-matter and total white-matter volumes in multivariable regression models in a large sample of adults. We found significant inverse associations between PM2.5 concentration and total white-matter volume and between PM2.5, PM2.5-10, PM10, nitrogen dioxide, and nitrogen oxide concentrations and total gray-matter volume in models adjusted for age, sex, body-mass index, self-assessment of overall health, frequency of alcohol use, smoking status, educational attainment, and income. These findings of pollutant-associated decreases in total gray-matter and total white-matter volumes are in the context of mean PM2.5 concentrations near the upper limit of the World Health Organization's recommendations. Similarly, mean PM10 concentrations were below the recommended upper limit, and nitrogen dioxide concentration was slightly above. Still, there are many areas in the world with much higher concentrations of these pollutants, which could be associated with larger effects. If replicated, these findings suggest that air pollution could be a risk factor for neurodegeneration.

Association between exposure to air pollution and prefrontal cortical volume in adults: A cross-sectional study from the UK biobank.

Associated with numerous cognitive and behavioral functions and with several diseases, the prefrontal cortex is vulnerable to environmental insult. Among other factors, toxins in air pollution have been associated with damage to the prefrontal cortex in children and older adults. We used data from the UK Biobank to assess further associations between an array of toxins in air pollution and gray matter in the prefrontal cortex including the left and right frontal poles, left and right superior frontal gyri, left and right frontal medial cortex, left and right orbitofrontal cortex, and left and right frontal opercula, using multivariate models adjusted for covariates that possibly could confound the association between air pollution and volume of prefrontal gray matter. The results showed inverse associations between PM 2.5, PM 10, and nitrogen oxides and prefrontal volume in models adjusted for age, sex, education, socioeconomic status, race-ethnicity, self-rated overall health, body mass index, total brain volume, smoking status, and alcohol use frequency. Education appeared to moderate the association between air pollution and prefrontal volume. The data in these analyses came from regions whose mean PM 2.5 was near the upper limit and whose mean PM 10 was under those recommended by the World Health Organization. These findings suggest that comparatively low levels of air pollution might be associated with reduced volume of the prefrontal cortex.