Approximately a quarter of a billion people undergo surgery every year hoping that the operation will alleviate symptoms, cure diseases, and improve quality-of-life. A concern has arisen that, despite the benefits of surgery, elderly patients might suffer neurological injury from surgery and general anaesthesia leading to persistent cognitive decline. However, many studies of postoperative cognition have had methodological weaknesses, including lack of suitable control groups, dissociation of cognitive outcomes from surgical outcomes, sub-optimal statistical techniques, and absence of longitudinal preoperative cognitive assessments. Emerging evidence suggests that after early cognitive decline, most patients return to their preoperative cognitive trajectories within 3 months of surgery; some even experience subsequent cognitive improvement. In this review, we summarize the scientific literature on perioperative cognition. We propose that the most important determinants of the postoperative cognitive trajectory are the preoperative cognitive trajectory, the success of the surgery, and events in the perioperative period. Postoperative complications, ongoing inflammation, and chronic pain are probably modifiable risk factors for persistent postoperative cognitive decline. When surgery is successful with minimal perioperative physiological perturbations, elderly patients can expect cognition to follow its preoperative course. Furthermore, when surgery alleviates symptoms and enhances quality-of-life, postoperative cognitive improvement is a possible and desirable outcome.
Keywords: anesthesia recovery period; postoperative period, cognition; preoperative period.