Does active travel behaviour moderate the association between the built environment and depression?

Background: Built environment characteristics have been associated with depressive symptoms, whilst active travel behaviour is linked to improved mental health. However, it remains unclear whether active travel buffers associations between increased exposure to the built environment and worse mental health. Methods: In this pre-registered study, participants were 10,310 mothers (mean age = 28.11, SD = 4.83) participating in the Avon Longitudinal Study of Parents and Children (ALSPAC). A latent built environment factor was measured at study enrolment, active travel behaviour at a 2-year follow-up, and depressive symptoms at a 4-year follow-up. Moderation was examined using adjusted linear regression models including an interaction term between the built environment factor and active travel behaviour. Results: The built environment factor was positively associated with depressive symptoms ({beta} = 0.023, p = .012). Active travel behaviour was not associated with depressive symptoms ({beta} = -0.002, p = .854) and did not moderate the association between the built environment factor and depressive symptoms ({beta} = -0.002, p = .865), after adjusting for covariates, including age, familial depressive history, socioeconomic risk factors, physical activity, baseline depressive symptoms and smoking. Conclusion: Contrary to expectations, active travel behaviour does not modify associations between the built environment and depressive symptoms. These findings provide no evidence that active travel mitigates mental health risks associated with the built environment in this population.