Social support, exhaled nitric oxide, and upper respiratory symptoms in health and asthma

Accumulating research identifies a role of psychological process, particularly negative affect, in the expression of airway nitric oxide (NO), yet directional associations tend to vary across methodologies and samples. Recent findings indicate higher social support to be associated with higher airway NO; however, consequences for respiratory infection remain unexplored. NO has a key role in the first line of epithelial defense against pathogens, thus, social support could unfold airway protective effects through enhanced production of NO. We therefore examined the associations among social support, negative affect, airway NO, and cold symptoms in a sample of undergraduate students. In this cross-sectional study, 637 participants completed questionnaires of social support, negative affect, medical history, and current cold symptoms followed by measurements of fractional exhaled NO (FE_NO) to study airway NO during a semester period of relative low stress. Findings showed that greater social support was associated with higher FE_NO and fewer cold symptoms, controlling for key covariates. Further analysis suggested an additional indirect effect of social support on FE_NO through cold symptoms such that higher social support was related to lower cold symptoms, which were related to lower FE_NO. These results, coupled with longitudinal findings in the previous research, suggest that social support can affect FE_NO and cold symptoms through a complex pattern of direct and indirect effects. Overall, findings support the role of psychological processes - particularly social support - as relevant to FE_NO and cold symptoms in young adults.