Inclusion Criteria:  age >65 year scheduled for AVR surgery Able to play the BAMCOG games after instruction (Near) native (dutch)  Exclusion Criteria:  mental disorder learning disorder diagnosed dementia at start of study alcohol abusus lithium/clozapine use because of DeltaScan sedation/RASS -4/-5 because of DeltaScan not able to sign informed consent implanted pacemaker, defibrillator or neurostimulator because of pilocarpine iontoferese history of insults pregnant women allergy to pilocarpine damaged skin (forearm)