A systematic review of urban green and blue spaces and cognitive function including discussion of mechanistic pathways

Abstract Background and Aim: Urban green and blue spaces have been found to have health enhancing properties (e.g. promotion of physical activity, social connectedness, and stress reduction). We examined the associations of urban green and blue spaces and cognitive function and aimed to identify any mechanistic pathways involving urban green and blue spaces and cognitive function. Methods: The initial search from four databases (MEDLINE, Embase, PSYCHInfo, Web of Science) yielded 4838 studies when duplicates were removed to undergo abstract screening. Following abstract and full text screening, included studies were classified as ‘observational’ (proximity to urban green and blue space, n=28/35) or ‘intervention’ (n=7/35). Results: Of the included studies, 71.4% (n=24/28) of ‘observational’ studies and 57.1% (n=4/7) of ‘intervention’ studies found positive associations indicating urban green and blue space is beneficial for cognitive function (i.e. enhanced cognitive function, lowered risk of cognitive impairment or protective of cognitive function). Overall, 71.4% (n=20/35) of studies included within this review were considered to have a medium risk of bias. Discussion: Current studies have identified relationships between urban green and blue space and cognitive function however, further work is required globally to broaden our understanding and provide a reliable evidence base. Current literature has elucidated numerous mechanistic pathways by which urban green and blue spaces have the capacity to operate within including Attention Restoration Theory and Stress Reduction Theory. Conclusion: Advancing the evidence of the mechanistic pathways between urban green and blue space and cognitive function is required. This may advise future urban green and blue space policies to improve the health and well-being of the environment and the globally ageing population.