Socioeconomic status and inflammatory processes in childhood asthma: The role of psychological stress

Background: Although social environment variables such as socioeconomic status (SES) have been linked to childhood asthma, little is known about the psychobiological mechanisms underlying this relationship. Objectives: The goal of this study was to investigate relationships among SES, psychological stress, and immune processes implicated in asthma. Methods: Thirty-seven children ages 9 to 18 years, physician-diagnosed with asthma, and 39 healthy children participated. Families were interviewed about chronic life stress, perceptions of threat, and SES. Blood samples were drawn from children to assess stimulated production of cytokines implicated in asthma (IL-4, IL-5, IL-13) and eosinophil counts. Results: In children with asthma, lower SES was associated with heightened production of IL-5 and IL-13 and higher eosinophil counts (P values < .05). Lower SES also was associated with higher chronic stress and perceived threat (both groups: P values < .05). Higher levels of stress and threat perception were associated with heightened production of IL-5 and IL-13, and higher eosinophil counts in children with asthma (P values < .05). Statistical mediation tests revealed that chronic stress and threat perception represented statistically significant pathways between SES and immune processes in children with asthma (P values < .05). In healthy children, associations were in the opposite direction from the asthma group, though generally not significant. Conclusion: This is one of the first studies to document empirically a psychobiological explanation for the epidemiologic relationship between low SES and poor asthma outcomes. Clinical implications: Associations among SES, psychological stress, and immune pathways suggest that the experience of stress, particularly among lower SES children, has implications for childhood asthma morbidity.