The relationship between social capital and inflammatory biomarkers in early adulthood: A longitudinal study.

Higher levels of social capital (SC) are associated with better health status. However, there is little evidence of the impact of SC on biological health outcomes in the early ages. To identify the association between SC in adolescence and inflammation levels in early adulthood. Prospective study using data from 2435 participants from the Epidemiological Health Investigation of Teenagers in Porto cohort. SC was assessed at age 17 through a self-administered questionnaire, and high-sensitivity C-reactive protein (hs-CRP) and leucocytes were measured in a fasting blood sample at 17 and 21 years-old. A principal components analysis was performed to identify the domains of SC. Simple linear regressions were performed to assess the association between SC components and inflammatory status at 17 and 21 years old. Pathway analysis was performed to assess the direct, indirect, and total effects of SC on hs-CRP and leucocyte levels. We did not find a significant total effect between SC at 17 years-old and hs-CRP at 21 years-old. However, the Trust/Reciprocity dimension showed a significant direct effect between SC and hs-CRP levels at 21 (β = -0.065, 95% CI: -0.129; -0.001), as well as a significant total effect (β = -0.075, 95% CI: -0.139; -0.011). Regarding leucocyte levels, total SC at 17 years-old was associated with leucocytes levels at 21 (β = -0.115, 95% CI: -0.205; -0.024). Significant direct (β = -0.104, 95% CI: -0.194; -0.014) and total effect (β = -0.107, 95% CI: -0.199; -0.015) of Trust/Reciprocity on leucocyte levels were observed. Adolescents with higher SC have a low inflammatory level in early adulthood, especially those with greater levels of trust/reciprocity.