Postoperative delirium (POD) and postoperative cognitive decline (POCD) can be observed after cardiosurgical interventions. Taken together, these postoperative neurocognitive dysfunctions contribute to increased morbidity and mortality and higher economic costs. Preoperative risk factors of postoperative neurocognitive dysfunctions, such as decreased neuropsychometric performance or decreased cognitive daily activities, can be interpreted as reduced cognitive reserve. The aim of this study is to build up cognitive reserves to protect against the development of POD and POCD through preoperative, home-based, cognitive training.