Inclusion Criteria: Eligible patients were at least 65 years old and were scheduled to have hip/knee replacement.  Exclusion Criteria:  a past medical history of neurological or clinically evident neurovascular disease (e.g., Alzheimer's disease, other forms of dementia, stroke); patients diagnosed with malignant or benign tumors; Mini-Mental State Examination (MMSE) scores of 26 or less; American Society of Anesthesiologists (ASA) score greater than 3; a history of alcohol abuse and drug dependence; inability to read or severe visual or auditory deficits; unwillingness to comply with the protocol or procedures.