Greenspace exposure and children behavior: A systematic review.

We systematically reviewed the existing evidence (until end of November 2021) on the association between long-term exposure to greenspace and behavioral problems in children according to the PRISMA 2020. The review finally reached 29 relevant studies of which, 17 were cross-sectional, 11 were cohort, and one was a case-control. Most of the studies were conducted in Europe (n = 14), followed by the USA (n = 8), and mainly (n = 21) from 2015 onwards. The overall quality of the studies in terms of risk of bias was "fair" (mean quality score = 5.4 out of 9) according to the Newcastle-Ottawa Scale. Thirteen studies (45%) had good or very good quality in terms of risk of bias. The strength and difficulty questionnaire was the most common outcome assessment instrument. Exposure to the greenspace in the reviewed studies was characterized based on different indices (availability, accessibility, and quality), mostly at residential address locations. Association of exposure to different types of greenspace were reported for nine different behavioral outcomes including total behavioral difficulties (n = 16), attention deficit hyperactivity disorder (ADHD) symptoms and severity (n = 15), ADHD diagnosis (n = 10), conduct problems (n = 10), prosocial behavior (n = 10), emotional symptoms (n = 8), peer-relationship problems (n = 8), externalizing disorders (n = 6), and internalizing disorders (n = 5). Most of the reported associations (except for conduct problems) were suggestive of beneficial association of greenspace exposure with children's behaviors; however, the studies were heterogeneous in terms of their exposure indicators, study design, and the outcome definition.