Depressed children with asthma evidence increased airway resistance: "vagal bias" as a mechanism?

Abstract

Depression is prevalent in pediatric asthma, and implicated in asthma morbidity and mortality. Pathways linking stress, depression, and asthma are unknown. To examine, under controlled laboratory conditions, pathways by which depressive states affect airway function via autonomic dysregulation. Participants were 171 children with asthma, age 7 to 17 years, presenting to an emergency department for asthma exacerbation. Forty-five children with asthma and high depressive symptoms (D) were contrasted with 45 with low/no depressive symptoms (ND). Depressive symptoms, asthma disease severity, vagal and sympathetic reactivity to film stressors, airflow (FEV1), and airway resistance were compared between the groups. A subgroup with greater airway reactivity (nonmedicated FEV1<80% predicted) was also studied. Correlations among variables were examined for the entire sample. Groups did not differ in demographics, disease severity, medications, or adherence. The D group with FEV1<80% predicted showed greater airway resistance throughout all conditions (P = .03), and vagal bias in the film stressors. The D group's vagal response was significant for the sad stimuli: family distress/loss (P = .03), dying (P = .003), and death (P = .03). The ND group showed sympathetic activation to sad stimuli: lonely (P = .04) and dying (P = .04). Depressive symptoms were correlated with respiratory resistance (r = .43; P = .001) and vagal bias in scene 3 (r = .24; P = .03), and vagal bias (scene 3) was correlated with postmovie airway resistance (r = 0.39; P = .004). Children with asthma and depressive symptoms manifest vagal bias when emotionally stressed. Those with depressive symptoms and FEV1<80% manifest greater airway resistance. Depression, vagal bias, and airway resistance were intercorrelated for the full sample.