Can the choice of anesthesia shield the aging brain after tumor surgery?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Aged 65 to 90 years, either sex. 2. Scheduled to undergo elective brain tumor resection under general anesthesia. 3. American Society of Anesthesiologists (ASA) physical status I-III. 4. Expected operative time ≥ 2 hours and anticipated postoperative hospital stay \> 48 hours. 5. Able to communicate in Chinese and complete cognitive assessments. 6. Preoperative cognitive function intact: Telephone Montreal Cognitive Assessment (T-MoCA) score ≥ 18 and Confusion Assessment Method (CAM) negative. 7. No use of analgesic or sedative medications on the day before surgery. 8. Able to provide informed consent and willing to comply with postoperative follow-up through 180 days. Exclusion Criteria: 1. Preoperative use of medications that may affect postoperative cognition (e.g., long-term benzodiazepines, antidepressants, antipsychotics, or chronic sedative-hypnotic use that cannot be paused). 2. Preoperative delirium, dementia, diagnosed severe psychiatric disorder, or existing central nervous system disease. 3. History of alcohol addiction or drug abuse; suspected or confirmed long-term use of narcotic analgesics or sedatives. 4. Severe visual, auditory, or speech impairment that precludes communication and cognitive testing. 5. Severe cardiopulmonary disease: forced expiratory volume in 1 second (FEV1) or vital capacity \< 50% of predicted; New York Heart Association (NYHA) functional class III-IV; severe hepatic or renal insufficiency (creatinine \> 176 μmol/L, blood urea nitrogen \> 7.1 mmol/L, albumin \< 30 g/L, Child-Pugh class C, or preoperative dialysis). 6. Known difficult airway, malignant hyperthermia susceptibility, or other contraindication to general anesthesia. 7. Hypersensitivity or known allergy to ciprofol, propofol, sevoflurane, or other study-related agents. 8. Severe uncontrolled infection or endocrine disorder. 9. Concurrent participation in another clinical trial. 10. Judged unsuitable for enrollment by the attending surgeon, anesthesiologist, or principal investigator for any other reason.