The goal of this observational study is to investigate biomarkers and neurocognitive markers of neurodegenerative processes in obstructive sleep apnea patients. The main questions the study aims to answer are: * Does neurodegeneration assessed by neurobiological markers and neurocognitive test performance exists in obstructive sleep apnea? * Are these neurodegenerative markers are associated with the adherence to clinical prescribed positive airway pressure therapy? Newly diagnosed patients with obstructive sleep apnea will be observed during the use of clinical prescribed positive pressure therapy. Different study related investigations take place before and six months after treatment start. Researchers will compare after six months the group of adherent treatment participants with the non-adherent treatment participants group to investigate if differences in the observed neurobiological or neurocognitive parameters exist.