The purposes of this study are to determine whether long-term postoperative cognitive dysfunction (POCD) is occured after general anesthesia and anesthetic drugs have an effect on the result about POCD.

In present aging society, a surgery in geriatric patient is increasing. Patients older than 60 year are particularly affected for postoperative cognitive dysfunction (POCD) (26-41%). The patients experiencing POCD are at an increased risk of death in the first year after surgery. So, POCD is important because it can influence to patient's quality of life.

In the investigator's hospital, laparoscopic cholecystectomy is performed with increasing frequency in aging patients. So the investigator's study will be conducted in elderly patients during laparoscopic cholecystectomy. The anesthetic methods are divided into the following 3 kinds: sevoflurane, propofol, dexmedetomidine. These anesthetic drugs are used in general anesthesia generally. The control group include a spouse of the patient which must be older than 60 year and does not have anesthetic history.

After the surgery, the patients are discharged from the hospital, the investigators will check the postoperative cognitive function 4 times: 1week, 3months, 6months, 1 year later using the Korean version of telephone interview for cognitive status (TICS). The Korean version of TICS was validated tool for examination of cognitive function and this tool and mini-mental state examination (MMSE) be linked directly. The test will be administered to spouse simultaneously by telephone.

Sample size was calculated for the primary outcome parameters (whether long-term postoperative cognitive dysfunction (POCD) is occured after general anesthesia), and the investigators hypothesized that two groups are in this study, one group is for postanesthetic patients, another is for their spouses. Total sample size was calculated to 190.

Inclusion Criteria:

• ≥ 60 years old, scheduled for laparoscopic cholecystectomy under general anesthesia

Exclusion Criteria:

• diseases of the central nervous system, including dementia (Mini Mental Examination Score <24),
• consumption of major tranquilizers or antidepressants
• previous neuropsychological testing
• the patient's inability to comply and follow procedures or poor comprehension of the language used in the study.
• Parkinson's disease
• Patients with a severe visual or auditory handicap, illiteracy
• alcoholism (intake of >5 units of alcohol daily during the last 3 months)
• drug dependence
• those not expected to complete the postoperative tests were excluded as well