Impact of obesity on cognitive outcome in children with sleep-disordered breathing

OBJECTIVES: The objective of this study was to evaluate the impact of obesity on cognitive impairment, in children with obstructive sleep apnoea (OSA), children with OSA and obesity, and in normal controls. METHODS: Thirty-six children with OSA (group 1), 38 children with OSA and obesity (group 2) and 58 normal controls (group 3) were studied. The Total intelligence quotient (T-IQ), Verbal IQ (V-IQ) and the Performance IQ (P-IQ) scores were obtained using the Wechsler Intelligence Scale for Children - Third Edition Revised. All participants' parents filled out the questionnaire containing the attention deficit and hyperactive disorder rating scale to investigate symptoms of hyperactivity and attention deficit. Obese and non-obese children with sleep-disordered breathing (SDB) underwent polysomnography. RESULTS: T-QI and P-QI scores were significantly lower in group 2 with higher performance impairment at the subtest compared to other groups. In obese children, V-IQ was significantly correlated with age of onset (r = 0.335, p = 0.05) and duration of SDB (r = -0.362, p = 0.02), while P-IQ and T-IQ were correlated with body mass index (BMI) percentile (r = -0.341, p = 0.03) and respiratory disturbance index (RDI) (r = -0.321, p = 0.05), respectively. RDI and BMI negatively influenced T-IQ in obese children with OSA. No correlation was found between sleep parameters and IQ scores or subtest scores in all groups. CONCLUSIONS: Obese children with OSA showed higher cognitive impairment. Obesity has an additive and synergic action with that exerted by OSA, speeding up the onset of complications