This present study protocol was approved by the Medical Institutional Ethics Committee of Jiangsu province and Taizhou People's Hospital. Those elderly patients (aged ≥ 65 years) scheduled to undergo selective laparoscopic surgery for colon carcinoma in Taizhou People's Hospital from April, 2014, to January, 2017, were prospectively recruited in this present study. All the participants were required to offer the signed informed consent. Exclusion criteria were described as follows: (1) with major depression; (2) with preexisting or a history of dementia delirium; (3) with cognitive impairment which was defined with a Modified Mini-Mental State Examination (MMSE) score < 24; (4) with clinically neurologic disorder or psychosis. 182 eligible patients were included into our study; 22 of them were excluded for varied reasons (informed consent refusal, missing information, etc.). In total, 160 elderly patients undergoing laparoscopic surgery for colon carcinoma were included into the final analysis, which was shown in the patient CONSORT (Figure 1).