It matters how you exercise. Researchers at the University of Arizona, and USC neuroscience have found that where you exercise can be just as important for brain health.
A new study co-authored withUSC Professor David RaichlenIt has been shown that exercise in highly polluted areas can actually reduce the brain’s positive effects. The paperPublished online Wednesday in NeurologyThe medical journal of American Academy of Neurology ( ) gives an insight into the complex effects of air pollution on the brain.
An active lifestyle has many benefits beyond a better athletic performance. Regular exercise is a recommended way to improve brain function and increase body resilience to age-related illness. Research has shown that a high level of vigorous activity, particularly when sustained for a prolonged period, can reduce the risk of developing Alzheimers disease or dementia.
People who live in areas with high levels of pollution have a significantly worse brain health. Poorer cognition, dementia risk and brain volume can all be caused by air pollution such as car exhaust. However, scientists have not explored the effects of living in a polluted environment on exercise.
Outdoor exercise is affected by air pollution
Raichlen, senior author of the study and professor of evolutionary and human biology at the University of Minnesota, stated that while vigorous exercise was good for brain health and physical activity was beneficial, air pollution seemed to muffle some of these benefits. USC Dornsife College of Letters, Arts and Sciences. For example, vigorous exercise reduced white matter lesions, which is a key indicator of brain health. However, these benefits were lost in areas with high levels of air pollution.
We are not suggesting that we avoid exercise due to air pollution. We do recommend that we exercise in areas with high levels of white matter lesions, which can increase the risk of stroke and Alzheimer’s disease.
The study builds on a growing body USC research that has shown air pollution is linked to a variety of health issues, from Alzheimer’s disease to asthma.
A multidisciplinary neuroscience approach links brain health to air pollution
Researchers used data from a large ongoing study by the University to measure physical activity. UK Biobank, a large-scale database of biomedical data containing over 500,000 participants from the United Kingdom. One week, a subset was able to wear devices that measured physical exertion. The Axivity AX3, which looks like a wrist-worn fitness monitor, gathers more detailed information, including measures of intensity and duration of physical exercise.
Your body experiences impact forces every time you land. Raichlen explained that the device in this study detects a combination of these forces and not just your arm’s activity to help us determine the intensity of activity.
Brain scans multimodal MRI imaging were also performed on subjects to determine the volume of brain tissue and detect high-signal areas in the brain’s white matter. These areas, also known as white matter lesion, are associated to a variety of age-related brain diseases such as stroke, Alzheimers disease, and dementia.
The estimated amount of air pollution at the residences of participants was then measured using the activity and MRI data from 8,600 participants. Researchers considered specific types of pollution, including annualized levels of PM2.5 particulate matter, PM2.5 absorbance, and car and power plant exhaust.
Melissa Furlong, the lead author of the study, and an assistant professor at University of Arizona, stated that the levels of air pollutant measured in this study are found in cities and urban environments around the world.
She stated that New York City and Los Angeles have levels of pollution that are within the limits of the ranges we tested in our study. The amount of air polluting we examined in this study was well within the normal ranges for cities that most people would consider healthy.
The results were alarming. Vigorous physical activity was associated wit an increase in gray matter volume and a reduction in white matter lesions. However the benefits for white-matter lesion were eliminated when participants came from a heavily polluted area.
“Air pollution exposure is associated with a heightened risk of reduced brain health and dementiaall sorts of problems, Raichlen said. “It made sense that during exercise, as your rate of breathing increases, youre also increasing your exposure to air pollution.
Study suggests that urban air pollution exposure should be reduced, but not exercise.
Raichlen stated that the findings don’t recommend avoiding exercise in polluted locations. The team found no evidence of poor brain health from exercise in these areas. However, they did find evidence that air pollution could have a negative impact on some aspects of brain health. Raichlen stated that scientists now need to understand how the environment and lifestyle choices like exercise affect brain health, especially in relation to Alzheimer’s disease, dementia, and other age-related illnesses.
Raichlen stated that exercise is becoming a more accepted lifestyle choice that can reduce brain aging and increase the risk of developing Alzheimer’s disease.
These results highlight the importance of reducing air pollution in urban environments, Raichlen stated. No matter where you live, cleaning up the air will enable us all to reap the benefits from physical activity.
The National Institute on Aging, National Institute of Environmental Health Sciences and Arizona Department of Health Services supported the study. The Wellcome Trust and UK Medical Research Council are its founding funders. They also support UK Biobank with the British Heart Foundation, Cancer Research UK and Department of Health.
Raichlen has the following co-authors: Melissa FurlongAssistant professor at University of Arizona’s Mel and Enid Zuckerman School of Public Health. Gene E. AlexanderProfessor, Department of Psychology, University of Arizona Yann C. KlimentidisAssociate professor, Department of Epidemiology and Biostatistics University of Arizona