An exploration of the effects of the built environment on depression in the Wellington Region, New Zealand : a thesis submitted in fulfilment of the requirements of the degree of Master of Public Health at Massey University, Wellington, New Zealand

Abstract

Background: Depression is a major epidemic affecting millions of people globally. One of the most widely recognised contributors to this global epidemic is the decline in active transport and physical activity. To address this issue research has focused considerably on quantifying the walkability of neighbourhood areas in an attempt to measure the influence of the built environment on active transport and physical activity. A large proportion of this research has exclusively focused on adults, leaving a significant gap in knowledge in terms of the influence of the built environment on young people’s mental health. Young people are highly susceptible to the effects of their built environments as they can have restricted mobility due to those under 16 years being unable to drive. The aim of this research was to investigate the relationship between the built environment and depression amongst adolescents aged 12 to 18 years in the Wellington Region, New Zealand (NZ). Methods: A measure of the built environment was obtained by developing a walkability index, based on previously developed indices and measures. The measures used in this research were dwelling density, intersection density, mean normalized difference vegetation index (NDVI), average traffic volume and land-use mix. Both Euclidean and network buffer methods were employed as measures of the neighbourhood area, using a weighted population centroid with a distance of 800m. Depression was measured using the Reynold Adolescent Scale, sourced from the Youth’12 National Youth Health Survey by The University of Auckland Adolescent Health Research Group. Zero-inflated negative binomial regression was used to investigate any possible associations. Sex, age, prioritised ethnicity and household deprivation were included in the analysis as confounders. Results: The results obtained from the index validation process indicate that the built environment is associated with an increased likelihood of active travel to work for the 800m Euclidean buffer after accounting for sex, age, ethnicity, and socioeconomic factors. While the network-based buffer showed no significant association for both the count and zero-inflated models. Findings from the regression analysis between walkability (Euclidean buffer) and adolescent depression suggest that as walkability increases depressive symptoms in adolescent decrease. These suggest that living in a walkable neighbourhood results in lower depressive symptoms. Conclusions: The results add to the body of evidence that improving walkability has a positive impact on young people’s mental health.