Extraction table.

Given the ongoing trend of urbanization and the increased prevalence of specific mental disorders in urban settings, there is a need to better understand the link between urban living and mental health. Recent advances in urban mental health research have leveraged mobile electroencephalography to explore how brain electrical signals are influenced by urban stressors and resources. This study aims to synthesize the evidence from mobile electroencephalography measurements in the context of urban mental health. A systematic literature research was conducted in the databases PubMed/MEDLINE, Embase, PsycINFO and CINAHL in September 2023. The present review includes primary studies that used in-situ electroencephalography in real urban environments published since 2013. Four independent reviewers conducted the screening, while two researchers performed data extraction using Microsoft Excel and assessed risk of bias using the Effective Public Healthcare Panacea Project Quality Assessment Tool. The review has been pre-registered with the International Prospective Register of Systematic Review (PROSPERO) under the registration number CRD42023471636. Fifteen studies were identified, primarily examining power in alpha, beta, and theta frequencies in urban areas compared to less urbanized environments. Study findings exhibited significant heterogeneity; while some studies noted heightened brain activity in urban environments, others observed reductions compared to less urbanized or greener regions. Notably, certain demographic cohorts, such as adolescents, have been understudied. Moreover, descriptions of exposures were often inadequate for ensuring replicability, and gender considerations were seldom integrated into analyses. This systematic review provides insights into an emerging field of research which appears to be suffering from small sample sizes and a lack of methodological transparency and consistency. Interpretation of the seemingly contradictory results requires future studies to be more rigorous in documenting urban exposures and choice of brain components under investigation.