Study Shows Relationship Between Air Pollution and Brain Health

Study Shows Relationship Between air pollution and brain health

Clean air is one of the most important resources for sustaining life. Despite this fact, clean air is getting harder and harder to find. Instead, much of the air we breathe on a daily basis has been polluted in some way, shape, or form. This is especially the case in larger cities that contain more people per square foot than smaller cities. More people also means more cars, and more jobs, which ultimately leads to more inadvertent air pollution. 

When most people think about how air pollution affects them, they generally assume that their lungs are at risk. While this is certainly true, air pollution also affects other parts of the body, such as the brain. In fact, a recent study has found a possible link between long-term air pollution and cognitive decline. The study, entitled “Long-term exposure to air pollution and trajectories of cognitive decline among older adults” and conducted by Dr. Erin R. Kulick and colleagues, was published in the American Association of Neurology’s publication, titled Neurology. 

The study was designed to evaluate the association between long-term exposure to air pollution and cognitive declines in older adults. Past research has shown air pollution as a risk factor for cognitive decline, so this study was developed to learn more about the correlation between the two factors. At the start of the study, it was hypothesized that higher levels of air pollution would cause lower levels of cognitive function initially, with a sharp decline as the study progressed. 

For the study, two groups of adults living in northern Manhattan were carefully evaluated. The first group was made up of 5,330 participants in the Washington Heights-Inwood Community Aging Project (WHICAP) and the second group was made up of 1,093 participants in the Northern Manhattan Study (NOMAS). Participants from both groups were free of dementia at baseline, had at least one neuropsychological examination during the study period, had a primary address allowing for measurement of exposure, and had no missing data for confounding variables. 

In order to measure the amount of air pollution the participants were exposed to, several factors were taken into account. First, an estimate of air pollution for the previous year using the Environmental Protection Agency’s (EPA) Air Quality System measurements was evaluated. Specifically, researchers were looking at measures of nitrogen dioxide, fine particles, and larger particles that could be inhaled. Then, traffic pollution exposure was determined by each participant’s address in relation to the nearest major highway. To determine cognitive function, neuropsychological tests were standardized in z scores. 

The research showed that when WHICAP participants were exposed to higher levels of air pollution, the rate of cognitive decline increased. It is estimated that the effect of inhaling nitrogen dioxide for extended periods of time equates to one year of cognitive decline. However, cognitive decline was not seen in the NOMAS participants. This mixed result is consistent with other studies that have evaluated the relationship between air pollution and cognitive decline. Researchers who conducted the study noted that there was likely a selection bias at play in the NOMAS group. It was also recognized that the NOMAS group only analyzed cognitive changes twice, while the WHICAP group performed six follow-up neuropsychological examinations. 

Headshot of Premier Neurology & Wellness Center Provider, Dr. kashouty

Dr. Kashouty, a diplomate of the American Board of Psychiatry and Neurology (ABPN), practices general neurology with fellowship trained specialization in clinical neurophysiology. Dr. Kashouty finds the form and function of the nerves and muscles the most interesting part of neurology, which is what led him to specialize in neurophysiology with more emphasis on neuromuscular conditions. He treats all neurological diseases, but his main focus is to treat and manage headaches, movement disorders and neuromuscular diseases. 

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