Brain-derived neurotrophic factor in relation to central obesity in children with sleep disordered breathing

Sleep disordered breathing (SDB) represents common comorbidities of childhood obesity leading to interrupted sleep and sleep deprivation. Sleep deprivation alters secretion of brain-derived neurotrophic factor (BDNF), which is an appetite regulator. However, little is known about the relation between BDNF and central obesity in children with SDB. The aim of the study was to evaluate BDNF level and anthropometric indices in relation to SDB in children with obesity.

A prospective case-control study was conducted on 30 children with obesity (BMI > 95^th percentile) and 30 healthy lean children (BMI 5^th-85^th percentile). Polysomnographic, anthropometric data and BDNF serum level were obtained from all included children. Serum level of BDNF and anthropometric indices of obesity were assessed in relation to SDB in children with obesity. Regression analysis was done to determine predictors for SDB in children with obesity.

In comparison to healthy controls, anthropometric indices of central obesity were significantly higher while BDNF was significantly lower in obese children, especially those with SDB. Respiratory disturbance index has a significant positive correlation with anthropometric indices of central obesity and a significant negative correlation with BDNF level. Central obesity and decreased BDNF were associated with 2-fold increased risk for SDB. Waist circumference/height ratio and neck circumference/height ratio have 89.5%, 75% sensitivity and 81.23%, 84.62% specificity at a cutoff point > 0.62, > 0.24 respectively for prediction of SDB in children with obesity.

Central obesity and decreased BDNF represent independent predictors for SDB in children with obesity. Anthropometric indices adjusted to height are a simple screening tool for SDB in obese children.