OBJECTIVES: Little is known on long-term consequences of poor social relationships in adulthood. The study aimed to examine associations between social relationships at age 30 and internalising symptoms at age 42.

METHODS: Data was drawn from four waves of the Northern Swedish cohort (n = 1001, 94 % response rate). The outcome internalising symptoms was measured by a composite index of depressiveness and anxiety. A cumulative measure was constructed to reflect various aspects of social relationships. Multivariate ordinal logistic regressions were used, controlling for socioeconomic indicators and previous level of internalising symptoms.

RESULTS: An accumulation of poor social relationships indicators at age 30 is related to internalising symptoms at age 42 in women (OR 1.30; CI 1.11-1.52) and men (OR 1.17; CI 1.02-1.36). The associations remained significant after adjustment for covariates.

CONCLUSIONS: Poor quality of social relationships at age 30 can predict internalising symptoms 12 years later in both men and women even when previous mental health as well as financial disadvantage is accounted for. More research is required to further examine pathways and mechanisms as well as suitable interventions.