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Interplay of urban-living environmental factors may affect brain and mental health
Researchers from Charité – Universitätsmedizin Berlin, Fudan University Shanghai and Tianjin Medical University in China, and the European environMENTAL consortium report new findings on the effects of urban-living environments on mental health. In this section, they answer questions about their research findings.
What was the research question or scientific inquiry behind your study?
More than 50 percent of the world population lives in urban areas. By 2050, two-thirds will live in cities. Urban-living individuals are exposed to numerous environmental factors that may combine and interact to influence mental health. While individual factors of urban-environment have been investigated in isolation, no attempt has been made to model how complex, real-life exposure to living in the city relates to brain and mental health, and how this is influenced by genetic factors.
How did you approach the topic?
Using data of more than 150.000 participants, we identified urban-living environmental profiles and related them to psychiatric symptoms. We aimed to understand what combinations of environmental factors are most relevant for these psychiatric symptoms. We also identified regional brain areas that mediate the effect of the different environmental profiles on psychiatric symptoms. We investigated genetic variations derived from genome-wide analyses of these psychiatric symptoms and tested them for moderation of the regional brain-volumes correlated to urban environmental profiles.
What did you discover?
We found an environmental profile of social deprivation, air pollution, street network and urban land-use density that was positively correlated with symptoms of depression, mediated by brain-volume differences consistent with reward processing, and moderated by genes enriched for stress response, including Corticotropin-Releasing-Hormone-Receptor-1. Protective factors such as greenness and generous destination accessibility were negatively correlated with anxiety symptoms. The third urban environmental profile was correlated with an emotional-instability symptom-group.
What’s your takeaway?
By providing evidence for comprehensive urban-environmental profiles that affect distinct groups of psychiatric symptoms and are mediated by different brain mechanisms, our results characterised biological mechanisms underlying complex, real-life environmental adversity. The quantification of the contribution of each environmental factor to brain and psychiatric symptoms and their interplay in an urban-living environment could potentially aid in targeting and prioritizing future public health interventions.
Xu J et al. Effects of urban living environments on mental health in adults. Nat Med. 2023 Jun;29(6):1456-1467. doi: 10.1038/s41591-023-02365-w