Local Landscapes, Evolving Minds: Mechanisms of Neighbourhood Influence on Dual-State Mental Health Trajectories in Adolescence

Neighbourhood variation in socioeconomic deprivation is recognised as a small but meaningful determinant of adolescent mental health, yet the mechanisms through which effects operate remain poorly understood. This study used #BeeWell survey data from Greater Manchester (England) adolescents (life satisfaction: N=27,009; emotional difficulties: N=26,461) collected 2021-2023. Through Latent Growth Mixture Modelling, we identified four non-linear trajectories of life satisfaction: Consistently High (79.1%); Improving (4.5%); Deteriorating (3.3%); Consistently Low (13.1%); entropy = 0.66, and three non-linear trajectories of emotional difficulties: Low/Lessening (56.1%); Sub-clinical (39.5%); Elevated/Worsening (4.4%); entropy = 0.61. Mediation analysis then assessed: 1) whether neighbourhood deprivation predicted trajectory class membership; and 2) whether Community Wellbeing factors, measured by the Co-op Community Wellbeing Index (CWI), mediated these associations. Greater deprivation increased odds of following Deteriorating (OR = 1.08, [1.01, 1.15]) and Consistently Low (OR = 1.08, [1.05, 1.13]) life satisfaction trajectories but not emotional difficulties trajectories. Mediation analyses revealed Relationships and Trust (χ² = -0.007, [-0.014, -0.001]); Equality (χ² = 0.007, [0.001, 0.013]); Health (χ² = 0.014, [0.003, 0.025]); and Housing, Space, and Environment (χ² = -0.031, [-0.046, -0.015]) partially explained effects on sub-clinical emotional difficulties. Housing, Space, and Environment also mediated odds of Consistently Low life satisfaction (χ² = -0.037, 95% CI [-0.046, -0.015]). Findings advance understanding of the mechanisms underpinning neighbourhood effects on adolescent mental health.