Exposure to greenspace and bluespace in relation to cognitive functioning in children and adolescents - A systematic review

BACKGROUND AND AIM The field of green- and bluespace research including studies in relation to cognitive functioning is rapidly growing. Thus, there is a strong need to systematically review the existing studies. Several systematic reviews have been already published on this topic but none of them is specific to cognitive outcomes in children of the entire age range. Moreover, only few of them examined the effects of bluespace in addition to greenspace. Also, previous reviews were focused either only on observational studies or on experimental studies. Our systematic review focuses on cognition in relation to green- and bluespace in children and adolescents between birth and 18 years old and captures both observational and experimental studies. METHODS We followed the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) guidelines. Searches were conducted in two databases – PubMed and PsychInfo. Free-text terms related to outcome, exposure, and population as well as MeSH terms for outcome and population were used. Further, the reference lists of publications identified as eligible for full-text review were "snowball” searched to detect additional studies. RESULTS Records identified from PubMed (n=2030) and PsycINFO (n=1168) were deduplicated and screened. 22 publications were selected. 13 additional publications were identified through „snowball” search. The extration of data revealed heterogeneity among studies. Methodological flaws and differences between studies should be considered. First, various methods of exposure and outcome assessment were used. Second, risk of bias assessment revealed inappriopriate use of statistical methods including the confounding and modifying variables, and mediating methods, exclusion data from analysis and selective reporting of outcomes, and inappriopriate assessment of cognition. CONCLUSIONS Improvement regading the methodological quality of future studies is required: expertise from several domains such as environmental epidemiology, statistics, and psychology should be involved in conducting future studies. KEYWORDS: green space, blue space, cognitive development