Traffic-related air pollution impacts on cardiovascular health and the brain in MESA Air and the Cardiovascular Health Study

Research has demonstrated a relationship between exposure to ambient air pollutants and cardiovascular disease (CVD). Studies have shown associations between short-term exposures and elevated levels of air pollutants and cardiovascular events as well as between long-term exposure and cardiovascular mortality, coronary heart disease (CHD), and stroke. The biologic mechanisms underlying long-term exposure effects are hypothesized to include systemic inflammation, autonomic nervous system imbalance, changes in vascular compliance, altered cardiac structure, and the development of atherosclerosis. The Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA-Air) investigates the hypothesized biologic pathways underlying the relationship between air pollution and CVD among more than 6000 well-characterized participants with diverse backgrounds from nine locations in six states. MESA-Air is built on the framework of the Multi-Ethnic Study of Atherosclerosis (MESA); a 10-year, epidemiology study of cardiovascular risk factors and atherosclerosis initiated in 1999 by the National Heart, Lung, and Blood Institute (NHLBI). The central hypothesis of MESA-Air is that long-term exposure to PM_2.5 is associated with the rapid progression of coronary atherosclerosis and an increased risk of coronary events. As compelling evidence regarding the effects of air pollution on CVD continues to mount, the impact of air pollution on the brain is less clear. Vascular pathologies often are present in neurodegenerative diseases and studies suggest that systemic inflammation (a response to which the brain is particularly vulnerable) mediates cardiovascular effects. The MESA Air research program is currently investigating associations between air pollution exposure and cognitive decline, risk of dementia and MRI-detected brain abnormalities as part of the Cardiovascular Health Study; a longitudinal study of CHD and stroke in older adults. The goal of the MESA Air research program is to provide a broader understanding of the health risks associated with air pollution exposure while providing the evidence that will guide policy decisions affecting public health.