Social cohesion, depression, and substance use severity among young men: Cross-sectional and longitudinal analyses from a Swiss cohort.

Social cohesion, depression, and problematic substance use are intertwined and poorly understood.This study aimed to examine cross-sectional and longitudinal associations between social cohesion, depression and problematic substance use amongyoung men, age 21-25. We used 2nd wave (t <sub>1</sub> , 2012-2014, N = 6020) and 3rd wave (t <sub>2</sub> , 2016-2018) data from the on-going Swiss CohortStudy on Substance Use Risk Factors (C-SURF), assessing social cohesion, depression, and severity of alcohol, nicotine and cannabis use during both waves. Structural Equation Models (SEMs) were employed to examine pathways in both waves under the framework of longitudinal analysis. Social cohesion was directly associated with depression and problem nicotine and cannabis use and indirectly associated with problem alcohol, nicotine and cannabis use through depression at both t1 and t2. Social cohesion exerted direct effects on nicotine use and cannabis use severity, but not on alcohol use severity. Social cohesion had indirect effects on problem use of all three substances, mediated via depression. The predictive direction was from depression to substance use, rather than vice versa. Higher social cohesion at an early age appears to protect young males from depression and problematic substance use later in life. However, once problematic substance use is established, the direct effect of social cohesion diminishes and is mediated through personal depression. Therefore, promoting a more cohesiveneighborhood in childhood or adolescenthood could play an important role preventing depression and more severe substance use behaviors