Longitudinal effects of green, blue, and gray spaces on early adolescent mental health in the United States.

backgroundPhysical environments are linked to adolescents' well-being in various ways. Green and blue (natural) spaces may protect against psychopathology, while gray (urban) spaces may confer risk. The present study examines how exposure to green, blue, and gray spaces is associated with the growth of psychopathology in early adolescence.

methodWe analyzed four waves of data (ages 9-13) from the Adolescent Brain Cognitive Development Study (N = 11,866, 47.8% female). At each wave, parents rated youths' mental health symptom severity in broad domains of total, externalizing, and internalizing problems. Latent growth curve models were estimated to model symptom trajectories. We examined the associations of residential proximity to green, blue, and gray spaces with symptoms at baseline and over time using geocoded and satellite data.

resultsGreen space was associated with lower levels of internalizing problems at baseline, while gray space was associated with higher levels of total and externalizing problems at baseline; however, all these effects diminished with time. Gray space was also associated with a slightly less positive slope for internalizing problems. There were no significant associations with blue space. Most results attenuated to nonsignificance once sociodemographic variables were accounted for.

conclusionsGreen and gray space exposure may be positively and negatively associated with adolescents' psychosocial development, respectively. However, demographic variables such as gender and socioeconomic status may account for more change in early adolescent psychopathology than environmental variables. Regardless, greater attention to youths' green and gray space exposure could help promote mental health at a population level.