Obstructive Sleep Apnea and Neurocognitive and Cardiovascular Function in Children With Down Syndrome

All individuals participating in the study will be evaluated for obstructive sleep apnea syndrome (OSAS) with a baseline sleep study. Based on the results of the sleep study,individuals with OSAS will be randomly assigned into two groups. One group will receive continuous positive airway pressure (CPAP) and the other intervention group will receive sham CPAP(placebo) for four months. CPAP is a machine with a mask that fits over the nose, is worn during sleep and helps keep the airway open. Sham CPAP (placebo) is a machine that looks and sounds like a CPAP machine but does not give pressure so it does not treat OSAS. Individuals with normal breathing during the sleep study will not receive a machine, and will serve as controls. Individuals will also have baseline tests including blood tests, an echocardiogram (pictures of the heart), a walking test and learning tests. After 4 months, the baseline tests will be repeated in all participants. At the end of the study, all individuals with OSAS will get treatment.