Inclusion Criteria:  patient of 60 years old at least, patient about to receive a hip arthroplasty under general anesthesia, elective cardiac surgery with cardiopulmonary bypass, patient with a MMSE score > or = 20(/30), patient able to give informed consent  Exclusion Criteria:  emergency surgery, or surgery in a septic context, patient with a known dementia or altered MMSE score (under 20)