TUESDAY, Oct. 26, 2004 (HealthDayNews) -- Many elderly people suffer cognitive decline for up to two years after having surgery that requires anesthesia.
Fifty-nine percent of elderly patients experienced cognitive decline immediately after surgery. That number declined to 34 percent after three months, but then rose again to 42 percent two years later, new research finds.
The study was presented Oct. 26 at the American Society of Anesthesiologists annual meeting in Las Vegas.
"I would expect initial improvement at the time of hospital discharge," said study author Dr. Terri Monk, a professor of anesthesiology at Duke University School of Medicine. "By three months, they are out recovering and off medications. I don't find that strange at all. What was concerning was the fact that two years after surgery those who had cognitive decline once, again have cognitive decline."
Previous studies have shown a similar pattern in cognitive function after cardiac surgery.
Monk's research is one of the first large studies to look at non-cardiac surgery. The issue is important because more elderly people are having elective major surgery as surgical techniques have advanced.
"Because mortality has decreased, we're doing surgery on people that we would never have done in the past," explained Dr. Vincent Marchello, medical director of Metropolitan Jewish Geriatric Center in New York City. "But we're finding there are other 'side effects' of doing procedures and one is the issue of cognitive decline after surgery."
"This is a problem that is sprouting from the good," he added.
For this study, researchers followed 354 patients scheduled to undergo major, non-cardiac, elective surgery. All of the procedures required general anesthesia and most were either intra-abdominal or orthopedic, including knee and joint replacements. The average age of the participants was 69.5 years old, more than half (57 percent) were female, and they had an average of 13.5 years of education.
All participants were given the same series of tests before surgery, when they were discharged from the hospital, three months after surgery and again two years later. The tests measured such things as attention and concentration, and verbal learning ability.
At three months' time, the 59 percent of patients who had experienced cognitive decline when they were discharged from the hospital did experience improvements, but not as great as those who didn't exhibit decline at the time of their discharge. Those who were cognitively impaired at the time of discharge were more likely to still be cognitively impaired two years later.
It's not yet clear what is responsible for the decline, but the authors have some ideas. "Maybe it's an inflammatory response to surgery," Monk said. "There may also be a subset of patients who are predisposed [to cognitive decline] prior to surgery. Maybe they were having some mild cognitive changes that hadn't been detected and these people have less cognitive reserve."
The changes could also be more directly related to the anesthesia. "There may be some that are neurotoxic or cause some neurochanges that we're not aware of," Monks said. "The mechanisms of anesthesia are poorly understood."
The next logical step for researchers is to try and assess the role that anesthetics may be playing in cognitive decline, Monk said.
Then scientists can figure out how to fix or prevent the problem.
"We've known it [cognitive decline] exists after cardiac surgery," Monk said. "Mine is the second large study to show that it exists after non-cardiac surgery. We've identified the problem and validated that it does occur, and now we need to look at the mechanisms and interventions to minimize or prevent the problem."
More information
The American Society of Anesthesiologists has more on The Senior Citizen as a Patient.
