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.
The 575 patients they studied had been tested annually at the ADRC and include those with Alzheimer's-type dementia.
At the start of the study, 361 people had mild to moderate dementia, and 214 were dementia-free.
Those patients were divided into three groups: those who had surgery, those with illness, and a third group with neither.
"We were able to use patients as their own controls before and after surgery and to compare groups of patients over time, and we did not detect any evidence of a long-term cognitive decline. Our findings suggest that if older people physically recover from surgery, they should expect that within six months or a year, they will return to their previous level of cognitive ability, too," said Evers.
Knowing how people functioned for years before and after surgery or illness allowed them to learn whether a major event somehow changed their cognitive trajectories. But it did not, even in patients with dementia at the time of surgery.
"This is an important finding for persons with Alzheimer's and their families who may worry that a pending operation could adversely affect the patient's cognitive status. There has been a widespread belief that the memory and thinking abilities of patients with early Alzheimer's disease may worsen as a consequence of surgery, but the evidence from this study does not support that belief," said Dr. John C. Morris.
The study has been published in the November issue of the journal Anesthesiology.