Depression is a complex neuropsychiatric disorder that affects millions of people worldwide. Although many factors contribute to a person’s risk for developing depression, such as childhood trauma or stressful life events, genetic predisposition for the condition plays a prominent role. Findings from a recent study suggest that air pollution exerts harmful neuropsychiatric effects, especially among people genetically predisposed to depression.
Air pollution contains myriad toxic substances, including chemicals, gases, and particulate matter – a mixture of solid particles and liquid droplets that may have neurotoxic properties. Exposure to air pollution promotes oxidative stress and increases the risk of developing many chronic diseases, including cardiovascular disease, cancer, hypertension, and diabetes, markedly shortening people’s lives.
The new study involved 352 healthy adults living in Beijing, China, a city known for its high levels of air pollution and relatively homogeneous population. The investigators determined each participant’s genetic propensity for developing depression – referred to as a polygenic risk score – and tracked air quality near the participants' homes. Participants completed various mental tasks while undergoing brain scans.
The scans revealed that people who were exposed to air pollution performed poorly on mental tasks. This effect was more pronounced among those who had a higher polygenic risk score for depression as well as those exposed to the highest levels of air pollution. The findings held true even after considering other factors, such as age, sex, and education, which can influence depression risk.
These findings suggest that air pollution impairs neurocognitive function, especially among people genetically predisposed to depression. They also underscore public health efforts to ameliorate the harmful effects of pollution. Some evidence indicates that dietary components, such as omega-3 fatty acids and sulforaphane (a bioactive compound derived from broccoli), may negate some of the harmful effects of exposure to air pollution. Watch this clip in which Dr. Jed Fahey describes how sulforaphane provides protection from benzene, a carcinogenic compound present in air pollution.
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