Published online: April 15, 2020
Obesity and depression are each known to be associated with increased asthma severity and decreased asthma control. There is a high prevalence of both obesity and depression in children with asthma, but the mechanisms by which these factors adversely affect asthma are not well understood. One commonality observed in both obesity and depression is altered function in the autonomic nervous system (ANS), a key stress-response neural pathway affecting visceral organs including the lungs. Shift in ANS function towards a predominance of parasympathetic over sympathetic reactivity (i.e. “vagal bias”) is associated with compromised airway function in asthma, likely due to cholinergically-mediated smooth muscle constriction and increased mucus secretion in the airways.
In an article recently published in The Journal of Allergy and Clinical Immunology: in Practice, based on Miller’s ANS Dysregulation Model of Depression in Asthma (JACI 1987,2009), HSU et al proposed that stress-reactive dysregulation of the ANS (vagal bias) may be a common pathway by which both obesity and depression adversely affect airway function in children with asthma. Using the movie “E.T. the Extra-Terrestrial” as a stress stimulus, they studied ANS reactivity in 250 asthmatic children assessed for overweight/obesity (OV/OB) using BMI and depressive symptoms using the Child Depression Inventory (CDI). Their results show that neither OV/OB nor depressive symptoms alone affected pulmonary function during stressful movie scenes, but together they were associated with greater vagal/cholinergic reactivity (Vagal Bias) and compromised airway function.
These findings suggest that children with asthma who are both overweight/obese and depressed may have increased susceptibility to the effect of stress on their lung function. In real life situations, where emotional stress is an everyday occurrence and sometimes extreme, these findings may explain in part the increased difficulty in managing some overweight/obese children with asthma, where depression may be an unrecognized comorbidity. In light of the findings that these effects may be mediated in part by vagal/cholinergic pathways, anti-cholinergic asthma medications that target the cholinergic system in the airways may be of greater benefit in treating children with asthma and co-morbid overweight/obesity and depression.
The Journal of Allergy and Clinical Immunology: in Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.