Residential and school green and blue spaces and intelligence in children: The Generation XXI birth cohort.

Green and blue spaces have numerous health benefits. It has been hypothesized that contact with these spaces can have an important role in cognitive development, because it provides children with unique stimuli that can help develop curiosity, creativity, awareness, and control. This study aimed to estimate the association between exposure to green and blue spaces and the various measures of intelligence quotient (IQ) among children from Porto Metropolitan Area (Portugal). This investigation used data from the Generation XXI birth cohort. Exposure was assessed by Geographic Information Systems using vegetation indexes and measures of accessibility to urban green spaces and blue spaces in the surroundings of the residence and school, measured at 0, 4, 7 and 10 years. The outcome was the verbal, performance, and global IQ, measured using the Wechsler Intelligence Scale for Children (WISC-III), administered at age 10. Associations were estimated using crude and adjusted multilevel models. The mediation role of air pollution and physical activity was quantified. This study included 3827 children. The adjusted models showed that having green spaces up to 800 m of the residence was positively associated with performance IQ (1.30 95%CI [0.26; 2.35]) and global IQ (1.27 [0.18; 2.36]). No clear associations were observed regarding accessibility to blue spaces. Physical activity appeared to have a minor mediation role. Children with urban green spaces around their residences had higher performance and global IQ. Local actors in the sectors of public health and urban planning should promote the creation of green spaces close to residential areas.