Another Risk Factor for Dementia?

General anesthesia and increased dementia risk linked in preliminary study

/ Author:  / Reviewed by: Chris Galloway, M.D.

(RxWiki News) Having difficulty remembering things or developing dementia is not always a normal part of aging. Many different factors can contribute to the risk of dementia.

One recent unpublished study found that receiving general anesthesia may be one risk factor for dementia.

The research was presented at a conference and has yet to be published in a peer-reviewed journal.

These researchers found that individuals over age 65 were about 35 percent more likely to develop dementia if they had received general anesthesia within the previous 10 years.

"Discuss anesthesia risks with your surgeon."

The aim of the study, led by Francois Sztark, MD, PhD, of the University of Bordeaux in France, was to look at the risk for dementia among elderly patients who had received general anesthesia for a medical procedure.

Between 1999 and 2001, the researchers worked with a group of 9,294 participants over age 65 who did not have dementia when the study began.

Two years after the start of the study, 7,008 of the participants who still did not have dementia were asked about their history of general anesthesia or local anesthesia since the start of the study.

At this time, about a third of the patients (2,309, or 33 percent) had anesthesia within the previous two years. Overall, 19 percent had been exposed to general anesthesia and 14 percent had been exposed to a local anesthesia.

The patients then underwent follow-ups at four years, seven years and 10 years after the start of the study.

At each follow-up, the participants received a cognitive (mental) evaluation and a screening for dementia.

They were also asked at each follow-up whether they had been exposed to general or local anesthesia since the previous follow-up.

Over the remaining eight years of follow-up (the 10-year follow-up after the study began), 9 percent of the participants (632 total) developed dementia.

Of these, 284 probably had Alzheimer's disease, 228 possibly had Alzeimer's disease and the other 120 had dementia not caused by Alzheimer's.

While 37 percent of the dementia patients had received anesthesia, 32 percent of the patients without dementia had received anesthesia.

Among those with dementia, 22 percent had received a general anesthesia while 19 percent of those without dementia had received general anesthesia.

The researchers adjusted their results to account for demographic factors — such as age, race/ethnicity, gender, education level and socioeconomic status — and other factors that might also affect their risk of dementia.

These other factors included the participants' lifestyle habits, their weight, cardiovascular risk factors and disease histories, their medications, their disabilities and their depression symptoms.

The researchers also adjusted for whether the participants smoked, had diabetes, high blood pressure, or had had a stroke.

After the adjustment, the researchers calculated that individuals who had received general anesthesia at least once over the 10-year follow-up period were at a 35 percent higher risk of dementia compared to the patients who did not receive anesthesia.

One apparent limitation of the study was that the researchers did not appear to gather information on what surgeries the participants received or why they were put under general anesthesia.

It's possible that the conditions requiring general anesthesia were related to the dementia and were not included as factors for adjustment.

These findings have not been published yet in a peer-reviewed journal and should be considered preliminary.

The study was presented June 2 at Euroanaesthesia, the annual congress of the European Society of Anaesthesiology. Information regarding funding and disclosures was unavailable.

Reviewed by: 
Review Date: 
May 31, 2013
Last Updated:
August 14, 2013