This study aims to find out how often memory and thinking problems happen after surgery in people who already have memory issues before their operation. These memory problems are called postoperative cognitive decline (POCD). Older adults with memory problems before surgery may be more likely to have trouble with thinking, memory, and daily activities after their operation. This study will follow patients who already have memory problems before surgery and see how their thinking and memory change after surgery. The results will help doctors better understand how to care for these patients before, during, and after surgery.