This observational study aims to evaluate multiple dimensions of health in patients with Obstructive Sleep Apnea Syndrome (OSAS), before and after three weeks of ventilotherapy. Specifically, the study aims to identify pre- vs post-treatment differences in the following domains: * cognitive performance * blood expression of biomarkers related to neurodegeneration * psychosocial wellbeing Thus, patients will complete the following evaluations before (T0) and after (T1) ventilotherapy: * neuropsychological standard assessment * blood sampling * psychosocial self-reported questionnaires