Anesthesia Does Not Lead to Dementia, Study Finds

October 31, 2013

A new study provides reassurance to the millions of people who must undergo major surgery each year: general anesthesia does not appear to lead to an increased likelihood of developing Alzheimer’s disease or other forms of dementia.

The findings, published in Mayo Clinic Proceedings, come from an extensive analysis of people aged 45 and older living in Olmsted County, Minn. Researchers sifted through thousands of patient records, noting those who had undergone general anesthesia, commonly required before extensive surgical procedures, and those who had not. They found that undergoing anesthesia did not increase the likelihood of developing dementia in later years.

“It’s reassuring we’re adding to the body of knowledge that there is not an association of anesthesia and surgery with Alzheimer’s,” said Dr. David Warner, a pediatric anesthesiologist at the Mayo Clinic Children’s Center and a senior author of the paper. “There are a lot of things to worry about when an elderly person has surgery, but it seems that developing Alzheimer’s isn’t one of them.”

Concerns about the effects of anesthesia on the brain have been raised by reports that many patients, particularly elderly ones, experience some confusion or even delirium after undergoing general anesthesia. In some cases, memory problems or fuzzy thinking may persist for months or years after surgery and resemble dementia.

The problem may be especially acute in people with Alzheimer’s. Patients with the disease appear to be particularly at risk of deterioration in thinking and memory skills following anesthesia, and some studies suggest that exposure to anesthetics may increase the risk of Alzheimer’s.  

Some earlier research in animals had suggested that anesthesia may damage the brain and increase the risk for Alzheimer’s disease. Animals exposed to anesthesia had defects in their brains that resembled the damage of Alzheimer’s, including an increase in the toxic protein beta-amyloid, a hallmark of the disease.

For the current study, the researchers identified about 900 men and women who had developed dementia in their later years. They compared them to age-matched peers who remained mentally alert and free of memory problems.

About 70 percent of the patients in both groups needed surgery requiring general anesthesia. The results indicate that elderly surgery patients who receive general anesthesia are no more likely to develop Alzheimer’s or other forms of dementia over the long term than other seniors.

More research is needed to better understand the long-term effects of anesthesia on the brain. But these results do provide some reassurance for those who must undergo major surgery.

Still, a hospital stay and surgical procedure can be traumatic for anyone, particularly someone with Alzheimer’s disease, who may have an especially difficult time adjusting to strange surroundings, interruption of routines and a bustle of activity. Other reports have shown that people with Alzheimer’s who develop delirium may show an accelerated decline in their memory and thinking skills for at least five years after hospitalization. Though people with Alzheimer’s of course may need hospitalization for legitimate medical concerns, keeping hospital visits to a minimum is always a good idea.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by William J. Netzer, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.

Source: Juraj Sprung, M.D., Ph.D., et al: Mayo Clinic Proceedings, May 1 online edition.


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