Urban environment exposures and cognitive health: an evidence gap map of systematic reviews

With a rapidly ageing global population and continued trends in urbanisation, it is crucial that the influence of the urban environment on cognitive health is understood. One important part of this is understanding where the saturation and paucity of the literature sits across these topics. The aim of this study was to develop an Evidence Gap Map (EGM) that identifies all systematic reviews investigating the urban environment and their relationship to cognitive health outcomes. Three databases (PubMed, Embase, PsycINFO) were searched, studies screened, a quality appraisal of the studies conducted, and an EGM created. A total of 57 reviews (257 outcomes) were included in the EGM. Five reviews were classified as high quality, 43 moderate and nine as low quality. The evidence base is saturated with air pollution and ‘social environment’ (including educational attainment) exposures. Saturated outcomes included dementia, Alzheimer’s disease, and cognitive impairment. Topics with limited evidence included links between exposure to transport-related behaviours. There was also a paucity of literature examining child cognitive outcomes. This study provides an overview and interactive visual representation of the current evidence base regarding built, natural and social environmental exposures and cognitive health outcomes informing policy, practice, and research.