Abstract 840: Alterations of Cerebrovascular Flow Dynamics in Obese Children
Background: Obesity is associated with increased risk for cerebrovascular and cardiovascular events, however, there has been little focus on cerebrovascular function. The purpose of this study is to assess cerebrovascular flow velocity patterns and investigate their relation to cardiovascular risk factors in obese children.
Methods: Noninvasive ultrasonographic measurements were made in 53 obese children (age:12±3 years, body mass index(BMI):25±3 kg/m2) and 44 age-matched healthy lean children (BMI:17±2 kg/m2). Using transcranial color Doppler sonography, peak systolic (PSV), end-diastolic (EDV), and average peak flow (APV) velocities of middle cerebral artery were measured and pulsatile index as a parameter of vascular resistance was calculated. Pulsatile index was defined as (PSV-EDV)/APV. Quantitative B-mode ultrasound scans were used to measure intima-media thickness and diameters of the common carotid artery. Plasma lipid concentrations, indices of insulin resistance, and high sensitive C-reactive protein (hs-CRP) were assessed in the obese children.
Results: In obese children with BMI <25 (n=27), flow velocities and pulsatile index were not significantly different compared with controls. In obese children with BMI≥25 (n=26), pulsatile index was significantly higher compared with controls (1.05±0.12 vs. 0.92±0.14, p<0.01), because APV was significantly lower (0.73±0.16 vs. 0.79±0.14 m/sec, p<0.05), although PSV and EDV were not significantly different. A significant correlation was observed between pulsatile index and homeostasis model assessment of insulin resistance(r=0.41, p<0.05). BMI, blood pressures, intima-media thickness at carotid artery, hs-CRP, and plasma lipid concentrations did not correlate with cerebral blood flow velocities.
Conclusions: The present study indicates that obesity can adversely affect cerebral blood flow and resistance in the cerebrovascular bed already in childhood. Insulin resistance may be a main risk factor for cerebrovascular flow changes. Obesity not only is a risk factor for later cardiovascular disease, but also is associated with significant impairment of cerebral flow dynamics.