Inclusion Criteria:  ≥ 60 years old Undergoing major elective surgery (e.g., intra-abdominal, retroperitoneal, major orthopedic) with an expected postoperative stay of at least 1 night Evidence of cognitive impairment on baseline screening tests (i.e. any score < 90 on CBB or >10 on S-OMCT)  Exclusion Criteria:  Patients undergoing cardiac surgery Patients undergoing intracranial neurosurgery Patients with known substance use disorder (verbally declared by patients) Unlikely to comply with study assessment (e.g., no fixed address, without access to internet/computer/phone).