Cardiac Autonomic Function at Baseline and under Stress and Its Relationship to Circulatory Markers of Inflammation in Obese Compared to Nonobese Children: A Pilot Study

Abstract

Background/Aims: The autonomic nervous system (ANS) provides neurogenic control of inflammatory reactions. ANS changes in obesity may result in inflammation. This study sought to gain insight into cardiac autonomic dysfunction and inflammation in childhood obesity, and to gather pilot data on the potential relationship between altered ANS and inflammation. Methods: Fifteen obese children and adolescents without metabolic complications and 15 nonobese controls underwent heart rate variability and impedance cardiography testing during rest, mental stress, and physical stress. Inflammatory cytokines and immune reactivity were measured. Results: There was no statistically significant difference between groups in cardiac ANS testing at rest or in response to stress. Median high-sensitivity C-reactive protein (hsCRP) was higher in the obese group [obese 2.6 mg/l (IQR 1.6-11.9); nonobese 0.3 mg/l (IQR 0.2-0.7); p < 0.001]. Interleukin-6 and tumour necrosis factor-α were similar between groups. Immune reactivity testing (in vitro Toll-like receptor stimulation) revealed a strong, but comparable, inflammatory response in both groups. Conclusions: Obese children and adolescents without metabolic complications did not have cardiac ANS dysfunction. While hsCRP was elevated, systemic cytokines were not raised. Compared to prior studies, which often focused on children with obesity and its complications, it is encouraging that obese children without metabolic complications may not yet have autonomic dysfunction.