Surgery does not lead to memory loss and other cognitive problems in older adults, says a new study by researchers at Washington University School of Medicine in St. Louis.

In fact, study's researchers were not able to detect any long-term cognitive declines attributable to surgery in a group of 575 patients they studied.

"There's a perception that people go in for surgery, and they aren't quite the same afterward. The reports of cognitive deterioration have varied, but several studies have suggested it affects many elderly people. In my experience as an anesthesiologist, I've found this is a very common concern," said first author Dr. Michael S. Avidan.

Avidan and fellow investigator Dr. Alex S. Evers questioned those conclusions.

"We wondered how reasonable it was to compare people having surgery to people who were perfectly healthy. We thought a better comparison group might be people who were equally ill," explained Evers.

Previous cognitive studies tested surgery patients just before an operation and then retested them several months later.

In the new study, the researchers examined data from Washington University's Alzheimer's Disease Research Center (ADRC) to get better initial screenings.

The ADRC tests cognitive function in volunteers annually, beginning at the age of 50.

Having years of cognitive data on hand made it easier to map a person's cognitive trajectory before and after surgery or illness and see whether either had any long-term impact on cognitive performance.