Postoperative cognitive dysfunction (POCD) is a disease with restricted cognitive memory function and intellectual skills, which occurs after surgery with and without anesthesia. The POCD strongly depends on patient's age and the surgical operation type. The anesthesia procedure plays a pivotal role as well and regarding the current knowledge it is still uncertain which technique matches the lowest risk. Elevated stress level accompanied with regional anesthesia procedures are accused to cause POCD in elderly patients. The investigators address the question weather regional or general anesthesia leads to a pronounced POCD in dependence of stress incidence.