Going through surgery can take a significant toll on a patient’s physical health and capabilities, especially if they are elderly. A recent study found that the effects extend far beyond mobility and pain management, as the operation may also lead to a significant loss of overall cognitive sharpness.

Researchers tracked 560 adults over 70 with no signs of dementia for six years after major surgeries such as hip replacements and abdominal procedures, watching how their memory and thinking skills changed over time. They found that nearly 15% of participants experienced a sharp decline in memory and thinking abilities shortly after surgery, with their condition continuing to deteriorate over time.

The three biggest warning signs that made a person more likely to fall into a severe decline were: being older, having lower mental test scores before the surgery, and developing postoperative delirium, which is a mental state where a person has episodes of confusion and disordered thinking that can develop over hours or days after the surgery.