Cardiovascular autonomic function in overweight and obese children.

摘要

Childhood obesity has become an epidemic in the United States as its prevalence has increased dramatically in the last two decades. Altered cardiac autonomic nervous system (cANS) function is associated with childhood obesity, but the exact nature of this dysfunction has not been clearly identified. Furthermore, the mechanisms that link obesity with altered CANS function are currently unknown. This thesis includes data from a sample of normal-weight (body mass index: BMI 85th percentile), overweight (85 th percentile BMI 95th percentile), and obese (BMI > 95 percentile) children from the greater Minneapolis, MN metro area. Data were collected for the purpose of examining the following: the relationships between; adiposity, cANS function, and vascular function; the relationships between obesity, leptin and insulin resistance, oxidative stress, inflammation, and CANS function; and the effect of a 5-month dietary intervention on CANS function in overweight children. It was hypothesized that significant relationships would be found between cANS function and vascular function, insulin resistance, oxidative stress, and inflammation and would provide preliminary data to support a potential link between alterations in cANS function and the adverse metabolic and cardiac profiles of overweight and obese children. Furthermore, we hypothesized that changes in body weight and composition in overweight children due to a 5-month dietary intervention would result in improved CANS function as compared to overweight controls. The results of the studies indicated that: (1) cANS function is related to vascular function independent of confounding factors such as age, level of adiposity, insulin, and inflammation, (2) cANS function is related to leptin and insulin resistance, oxidative stress, and inflammation but that after adjustment for fat mass, the relationships are significantly lessened suggesting that the relationships between these factors appear to be dependent on quantity of fat mass and/or other factors associated with being obese, and (3) despite a decreased BMI after a 5 month dietary modification program, cANS function in overweight children did not significantly change. The results of these studies provide novel hypotheses regarding the link between increased adiposity and risk of future cardiovascular disease for overweight and obese children.