Residential greenness and adolescent mental health trajectories: A longitudinal pre-registered study

Exposure to natural environments, such as residential green spaces, has been proposed as a promising approach to health promotion and prevention of mental health issues among adolescents. This study investigated the association between residential greenness and trajectories of adolescent mental health. Participants (n = 245) were part of the Orygen Adolescent Development Study and reported on anxiety and depression symptoms, using the Beck Anxiety Inventory and Center for Epidemiologic Studies-Depression scale, at ages 12, 15, 17, and 19 years. Parent-reports of externalizing behavior was assessed with the delinquent behavior and aggressive behavior scales from the Child Behavior Checklist collected at the same time points. Residential greenness was measured using the Normalized Difference Vegetation Index (NDVI) at baseline within a 1600m road network radius. Robust linear mixed models were used to examine associations between NDVI and within-subject changes in mental well-being, allowing for the inclusion of participants with only one data point while accounting for missing data. An exploratory analysis examined the interaction with sex in the association between NDVI and mental health. None of the models investigating residential greenness and mental health trajectories indicated consistent associations. The application of alternative buffer zones or distance to nearest park did not alter the conclusion. Sensitivity analysis investigating the moderating effect of childhood maltreatment did not reveal notable effects. Exploratory analyses, however, found a link between higher levels of childhood residential greenness and decreases in externalizing symptoms over time in males (β: 0.31 [95 % CI -0.56, -0.06]), though no such observation was observed in females. Our study adds to the existing literature by highlighting the complex relationship between nature exposure and adolescent mental health. It emphasizes a need for future investigations to adopt a life-course approach and further explore potential sex differences and intersections of adolescent social identities with the potential benefits of nature.