To investigate the cross-sectional and longitudinal relationships between generalised trust and institutional trust and psychosomatic symptoms during middle and late adolescence. Data came from the Swedish cohort study Futura01, based on survey responses from 3,691 ninth-grade students (approximately 15–16 years, t1), who were reassessed two years later (approximately 17–18 years, t2). Sociodemographic details from registries were linked to the survey data. Linear regression models were employed. Longitudinal analyses used both the first difference (FD) method and the lagged dependent variable (LDV) method. Adjustments were made for gender, family structure, parental education level, parental country of origin, and upper secondary school programme. Elevated generalised and institutional trust were cross-sectionally linked to reduced psychosomatic symptoms at both measurement points. The FD analyses revealed that rises in generalised and institutional trust from ages 15–16 to 17–18 were linked to concurrent reductions in psychosomatic symptoms. The LDV analyses indicated bidirectional temporal relationships between trust and psychosomatic symptoms. These results suggest that trust functions as a social determinant of psychosomatic symptoms among adolescents, while also showing that health status may influence trust levels.
