Adolescent friendships and their association with self-rated health in early adulthood

Abstract Background Adolescence is a critical developmental period during which social relationships-particularly close friendships-may influence long-term health. Friendships can provide emotional support, reduce stress, and encourage healthier behaviours, all of which may contribute to improved self-rated health in adulthood. Despite growing recognition of social determinants of health, no cohort studies have specifically examined the significance of adolescent friendships for self-rated health in adulthood. The study investigates the association between friendships at ages 15 and 18 and self-rated health at age 29. Methods This prospective cohort study used questionnaire data from the West Jutland Cohort, in which participants reported on their close friendships at ages 15 and 18, and on their self-rated health at age 29. The outcome self-rated health was dichotomized as either high or low. Logistic regression analyses were adjusted for sex, family functioning, income, and parental education. Results At age 15, 89% of participants reported having at least one close friend, increasing to 92% at age 18. Having at least one close friend at age 15 was statistically significant associated with high self-rated health at age 29 (OR: 1.9, 95% CI: 1.1-3.2). The association at age 18 was positive but not statistically significant. Participants who reported close friendships at both ages 15 and 18 had a non-significant but positive tendency toward high self-rated health at age 29 (OR: 2.0, 95% CI: 0.6-6.6). Conclusions Close friendships in mid-adolescence may have a lasting impact on perceived health in early adulthood. These findings highlight the long-term health relevance of adolescent social relationships and underscore the value of early interventions that promote meaningful peer connections. Public health efforts aimed at fostering adolescent social support networks may contribute to long-term improvements in general health. Key messages • Having at least one close friend at age 15 is significantly associated with better self-rated health at age 29. • Strengthening adolescent social bonds may be a promising avenue for long-term health promotion efforts.