This systematic review aimed to identify mechanisms of psychological change following exposure to nature within an adolescent population. Keyword searches within Scopus, PsychINFO and Web of Science were carried out to include articles published by 14 September 2021. Records were reviewed in line with inclusion criteria: samples with an average age of 24 and under, exposure to nature vs. control using an experimental or quasi-experimental design and outcomes of mental health and psychological status. The review resulted in 27 papers that were assessed for methodological quality and manually searched for mediation analyses. A range of psychological outcomes were identified and grouped into 10 categories: Mood and Affect, Mental Health, Wellbeing, Perceived Restoration, Stress, Energy, Cognitive Functioning, Resilience, Self-Concept and Pro-Social Behaviour. Only one formal mediation analysis was reported, highlighting a mediating role of belonging in increases in resilience. Limitations include the majority use of university student samples and over half of the papers being of low methodological quality. No firm conclusions on key mechanisms in an adolescent population were made due to insufficient evidence of mediating variables. The development of methodologically rigorous experimental studies with the inclusion of statistical pathway modelling is needed to test and specify plausible mechanisms.
Keywords: adolescence; mechanisms; mental health; nature exposure; prevention; systematic review.