This study investigates the prevalence and predictors of postoperative cognitive dysfunction (POCD) in adults undergoing major noncardiac surgery. One thousand sixty-four patients aged 18 years or older were enrolled, categorized into young (18-39 years), middle-aged (40-59 years), and elderly (60 years or older). Neuropsychological tests were administered before surgery, at hospital discharge, and 3 months postoperatively. At hospital discharge, POCD was present in 36.6% of young, 30.4% of middle-aged, and 41.4% of elderly patients. At 3 months postoperatively, POCD was present in 5.7% of young, 5.6% of middle-aged, and 12.7% of elderly patients. The independent risk factors for POCD at 3 months included increasing age, lower educational level, a history of previous cerebral vascular accident without residual impairment, and POCD at hospital discharge. Patients with POCD at hospital discharge were more likely to die in the first year after surgery. The study confirms that advancing age is a significant risk factor for long-term cognitive problems after major noncardiac surgery, and patients with POCD are at an increased risk of mortality.This study investigates the prevalence and predictors of postoperative cognitive dysfunction (POCD) in adults undergoing major noncardiac surgery. One thousand sixty-four patients aged 18 years or older were enrolled, categorized into young (18-39 years), middle-aged (40-59 years), and elderly (60 years or older). Neuropsychological tests were administered before surgery, at hospital discharge, and 3 months postoperatively. At hospital discharge, POCD was present in 36.6% of young, 30.4% of middle-aged, and 41.4% of elderly patients. At 3 months postoperatively, POCD was present in 5.7% of young, 5.6% of middle-aged, and 12.7% of elderly patients. The independent risk factors for POCD at 3 months included increasing age, lower educational level, a history of previous cerebral vascular accident without residual impairment, and POCD at hospital discharge. Patients with POCD at hospital discharge were more likely to die in the first year after surgery. The study confirms that advancing age is a significant risk factor for long-term cognitive problems after major noncardiac surgery, and patients with POCD are at an increased risk of mortality.