Air pollution can impact adolescent brain development, OHSU study finds

A new study from Oregon Health & Science University found that air pollution can impact adolescent brain development. The analysis indicated that exposure to common air pollutants is associated with accelerated cortical thinning in areas of the brain responsible for language, mood regulation and socioemotional processing. Researchers observed changes even in children who were exposed to pollution at levels the Environmental Protection Agency considers safe.

Calvin Jara is an otolaryngology resident at OHSU and the study’s lead author. He joins us with more details about how these changes could affect children’s physical and emotional health.

Note: The following transcript was transcribed digitally and validated for accuracy, readability and formatting by an OPB volunteer.

Dave Miller: This is Think Out Loud on OPB. I’m Dave Miller. A new study from Oregon Health and Science University found that air pollution can impact adolescent brain development. The analysis found that exposure to common air pollutants is associated with changes in parts of the brain that could negatively affect language, mood regulation, and socio-emotional processing. Calvin Jara is an ear, nose and throat resident at OHSU and the study’s lead author. He joins us now. It’s great to have you on the show.

Calvin Jara: Thank you so much for having me. Appreciate the time.

Miller: Why is adolescence such an important time for brain development?

Jara: It’s a great question. Adolescence is one of the most dynamic periods in brain development, but overall, health development. I think a great analogy can be thinking about the body and the brain being under construction. There’s extensive remodeling going on, you’re having changes in neural networks, making things more efficient and growing.

The regions that are ultimately affected during this process – decision making, emotional regulation, attention, impulse control – all of these things are growing, and ultimately the brain is very plastic, which allows for learning and adaptation. But in that process, it also makes it very vulnerable, and so that’s what essentially makes it such an important period during adolescence to think about.

Miller: What made you want to look at air pollution specifically?

Jara: Air pollution, part of it is personal. I’m from New York, contrary to popular belief, there are green spaces out there. I grew up a relatively healthy child, and I had the opportunity in my early 20’s to travel a bit of the world. And when I came back, I had adult-onset asthma. One of the questions at the time I was asking myself is, did I always have asthma? How did it happen now? Is there something in my genetics that predisposed me to this? Was there an environmental exposure that happened?

Often it’s the case – and I like to think about it in this way, especially with chronic disease and conditions – we might be sick today, not because of something that acutely happened, but because of what has accumulated and synergistically acted in the past.

Air pollution is something that stands out to me because it’s universal, it’s invisible, and a lot of times, it’s not a matter of individual choice, it’s shaped by where you live or work or go to school. Air pollution is something that has an ongoing strong evidence that links it to cardiovascular and respiratory disease, and even more so these days in cognition and mental health outcomes. This is a particular area of note that I think is interesting to continue studying.

Miller: Your study was based on analysis of data that came from something known as the ABCD study. What is that?

Jara: The ABCD study is short for Adolescent Brain and Cognitive Development Study. It’s one of the largest longitudinal studies in brain development and child health in the United States. It’s following around 12,000 children from ages nine,ten, and we’re collecting detailed brain imaging, cognitive testing, looking at mental health assessments and environmental data over a period of time. So it’s not just a snapshot, it’s essentially looking at patterns, which makes it, I think, a very interesting and suitable way to look at how environmental factors ultimately influence brain development and a host of other things to think about.

Miller: And what exactly were you looking at in that huge repository of data for your study?

Jara: To try to boil it down, ultimately was looking at how air pollution may be associated with structural brain changes. If you think about air pollution, simply put, it’s fine particulate matter that can go into the lungs. It travels throughout your bloodstream. It can cause inflammation and get into organs like the brain. In the study, we did find that higher levels of exposure to air pollution was associated with subtle differences in brain structure, and particularly those areas of executive function and emotional regulation.

I want to be clear in saying, it’s not like brain damage or any sort of clinical diagnoses. To me, what a lot of these things suggest is altered timing or trajectories in brain maturation, and when you think about it on a population-based level, especially at levels below maybe what the Environmental Protection Agency may deem safe air pollution levels, I think that becomes something meaningful when you’re seeing these changes in large populations.

Miller: And so just to be clear, what you found was a correlation between physical brain changes that could possibly result in emotional or behavioral problems, and places with higher levels of air pollution.

Jara: The structural changes, and the term is cortical thinning. The brain’s outer layer gradually thins as it matures. It’s actually a very normal process, and what we found was accelerated cortical thinning. The way I think you could think about it is that the brain may be maturing faster than expected in some regions, especially during a period that is very tightly choreographed.

The analogy may be something to the effect of, if you’re undergoing – again, I go back to the construction – construction, and you have some rooms getting remodeled too early or before others might be ready, how does this ultimately affect the functional impact of those changes? How does that affect Life Course Health as well? These are some of the associations that we were looking to find.

Miller: When you say faster maturation of parts of the brain than would be “normal,” that, to me, doesn’t necessarily sound negative. But have there been studies that have found negative outcomes from that cortical thinning at an early age?

Jara: Well, there aren’t many longitudinal adolescent studies that are looking at how air pollution is affecting brain structure and function. There are more and more that are coming. I think what’s also been interesting to note is how air pollution is affecting neurodegenerative disease later in life.

If you have someone who, for example, comes into your emergency room and they have emphysema, you can ask yourself the question, when did this happen? Is this something that happened in recent time? Or, maybe I should look back in their – maybe it’s a 70-year-old patient – in their 40s and 50s, and then you go back then and you could say, OK, well, maybe they were a smoker or they had some sort of asthma. Well, why don’t you go back further and further?

And so looking at the life course health and accumulation of environmental exposures that people are undergoing, that look at outcomes.

Miller: I want to go back to what you said, quickly, to make sure that I didn’t miss it. How high were the levels of air pollution that were correlated with this cortical thinning?

Jara: There are varying levels of air pollution across the United States, and something that people often think about is urban locations, and of course urban locations are generally associated with higher levels of air pollution as well as levels that are more persistent. But I don’t think that this is just an urban versus rural story.

Exposure can be closely tied to housing patterns and traffic density and socioeconomic factors as well, and so these levels were not higher per se in various parts that we were seeing some of these changes than what the EPA deems as safe. That’s what I think is partly concerning, but also something to continue to look at – essentially the question of what is a truly safe level of air pollution?

The World Health Organization in 2019 noted that something to the effect of 99% of the world living under conditions that are not deemed “safe,” and so there’s a ton of variability and we’re seeing some of these changes at levels that are also deemed safe.

Miller: Meanwhile, just this morning, the New York Times reported that when doing the cost-benefit analysis of potential air pollution limits, the EPA going forward could look at the cost to industry of regulations, but not the value of saving human lives. What’s your response to this news?

Jara: It’s an interesting take. To be fair, it’s a little bit outside my scope and I’m curious to actually learn more about it. But a cursory view and thought… I’m wondering if that change potentially narrows the lens. For a long time you think about cost-benefit analysis, recognizing that cleaner air doesn’t just help the environment, cleaner air helps prevent disease, hospitalizations, premature deaths – all of which do carry real, if you want to talk about economics, economic consequences for families and communities.

I think that if we’re removing some of those benefits from the equation, I wonder if we are not necessarily thinking about the holistic perspective of what’s best for public health. The science is very clear that air pollution has measurable long-term effects on health, particularly for our most vulnerable populations being children in the United States.

Miller: Parents have a lot less control of the air their kids breathe than they do of other aspects of their kids’ lives. What do you recommend to families right now who are thinking about their kids’ lungs, brains?

Jara: Absolutely. I think first and foremost, it’s not meant to be a message of panic, but I agree, at the individual level control is fairly limited, but I think some steps that families can take, can think about monitoring air quality reports, reducing outdoor activity on high pollution days, especially here in Oregon during wildfire season. Oregon has some of the best air in the country, but during wildfire season that is not the case, and that’s something to take note of.

Improving indoor air filtration when possible, thinking about green spaces for our children to play in. I think the most effective interventions ultimately are going to be collective, when we’re all empowering one another with this knowledge and also working with local and state leaders to enact policy that makes sense for our kids.

Miller: Calvin Jara, thanks very much.

Jara: Thank you for having me. I appreciate it.

Miller: Calvin Jara is an otolaryngology resident and ear, nose, and throat doctor at OHSU.

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