This student story was published as part of the 2023 NASW Perlman Virtual Mentoring Program organized by the NASW Education Committee, providing science journalism practice and experience for undergraduate and graduate students.
Story by John Carlo Jadormeo Combista
Mentored and edited by Mark Shwartz
Air pollution and a lack of access to basic resources increase the risk of depression in young people in disadvantaged urban neighborhoods, according to recent studies in the United States and China.
Depression affects millions of children and adolescents worldwide, and exposure to air pollution has long been associated with an increased risk of depression. Now researchers are finding new evidence that growing up in a low-income urban environment increases that risk.
In January, researchers from the U.S. and China published the first nationwide study linking air pollution and mental health decline in people living in urban areas. The study, led by Meng Li of the University of Houston, used real-time search data from Baidu, the dominant internet search engine in China, to estimate the impact of air pollution exposure on the mental health of residents in 252 Chinese cities.
The study revealed that people in less economically developed cities suffer from more mental health problems caused by air pollution. Better access to mental health resources and green spaces could improve individual well-being and alleviate pollution’s negative effects, the researchers concluded.
"We revealed the causal effects of air pollution on people’s mental health at a national level and further showed that this impact becomes stronger as the duration of exposure to air pollution increases," Li said. "Our research may be helpful to governments all over the world when they are considering the policy to mitigate the negative effects of climate change on their urbanites."
Other recent studies have shown that breathing polluted air can affect the developing brain. In June 2023, researchers in China found that outdoor air pollution increases the risk of depression and suicide in children and adolescents due to long-term changes in the structure and function of their brains.
Gray matter
The brain consists of approximately 60 percent white matter and 40 percent gray matter. The gray matter processes information and enables learning, thinking, and reasoning. Several studies have found an association between a reduced volume of gray matter in the frontal lobe, specifically the medial prefrontal cortex, and major depressive disorders.
"Depression is one of the big drivers of morbidity and disability in people with mental illness," said Hao Yang Tan, lead investigator at the Lieber Institute for Brain Development.
In a 2021 study conducted in China, Tan and his colleagues used MRI scans to compare the brains of healthy adults raised in urban neighborhoods with those of healthy adults from rural areas. They found that the volume of gray matter in the medial prefrontal cortex was reduced in people with urban childhoods compared with their rural counterparts. Urban-raised adults also experienced reduced medial prefrontal activation in response to memory tasks involving stress from social threats, such as playing against a competitor. These findings suggest that social stressors, such as socioeconomic disparities, may contribute to the risk of depression through stress-related alterations of brain structure and function.
A follow-up study in China focused on how genetic and environmental factors increase the risk of depression. Tan and his colleagues found that individuals with higher-risk genes for depression who were exposed to significant air pollution had much larger stress-related changes in brain function than people at lower genetic risk.
Neighborhood disparities
Air pollution disparities vary greatly across neighborhoods, and research shows that marginalized communities are often exposed to higher levels of pollution. A 2022 study from the University of Chicago found that infants raised in poor U.S. neighborhoods face increased exposure, and that the combination of breathing toxic air and growing up in poverty reduces a child's cognitive abilities by age 4.
"Living in spaces in neighborhoods with access to parks and green spaces is a hypothesized factor that could influence depression and behavioral outcomes," said Max Aung, an assistant professor at the University of Southern California Keck School of Medicine.
Aung and USC postdoctoral scholar Carlos Cardenas-Iniguez are co-principal investigators on a pilot project studying the link between air pollution, neighborhood factors, and depression and anxiety in children of U.S.-born and immigrant parents.
"You live in a neighborhood that doesn't have a lot of parks, and the more you add ‘does not have,’ the more stressful it is to live in such neighborhoods," Cardenas-Iniguez said. He emphasized that it is crucial to educate the public, especially parents, about the importance of protecting children’s mental health by working with local officials to shape policies addressing key risk factors, such as air pollution and urban living conditions.
"If we can address depression, especially in adolescence and childhood, it can potentially help ameliorate some of the downstream economic implications and consequences that could happen in adulthood," Aung added.
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John Carlo Jadormeo Combista is a licensed pharmacist from the Philippines who is pursuing a PhD in Neuroscience and Cognitive Science at the University of Maryland, College Park. He is interested in understanding how the brain develops and what causes neurological diseases and disorders to arise. Outside academia and writing, he is passionate about singing and volunteers his free time to work with vulnerable populations, such as children..
The NASW Perlman Virtual Mentoring program is named for longtime science writer and past NASW President David Perlman. Dave, who died in 2020 at the age of 101 only three years after his retirement from the San Francisco Chronicle, was a mentor to countless members of the science writing community and always made time for kind and supportive words, especially for early career writers. Contact NASW Education Committee Co-Chairs Czerne Reid and Ashley Yeager and Perlman Program Coordinator Courtney Gorman at mentor@nasw.org. Thank you to the many NASW member volunteers who spearhead our #SciWriStudent programming year after year.
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