Elderly patients who are exposed to general anesthesia have a 35% higher risk of developing dementia, researchers from INSERM and University of Bordeaux, France, reported at Euroanaesthesia, the annual congress of the European Society of Anaesthesiology (ESA).

Dr Francois Sztark and team explained that POCD (post-operative cognitive dysfunction), a common complication of major surgery, could be linked to dementia several years after the procedure.

Dr. Sztark said that experts believe there may be an association between POCD and subsequent dementia due to a common pathological mechanism through the amyloid β peptide. According to a number of studies, some anesthetics might trigger inflammation of neural tissues leading to POCD, as well as Alzheimer’s disease precursors, including neurofibrillary tangles and β-amyloid plaques. However, nobody was certain whether POCD might be a precursor to dementia.

Sztark and team analyzed dementia risk associated with anesthesia. They focused on patients aged 65+ years. The researchers looked at data from the Three-City study, which was designed to assess dementia and cognitive decline risk due to vascular risk factors. The study included data on 9,294 community-dwelling French seniors in Montpellier, Dijon and Bordeaux (between 1999 and 2001).

The seniors were interviewed at the start of the study, and then again 2, 4, 7 and 10 years later. Each assessment included a thorough cognitive evaluation with systematic screening for dementia. From the second follow up, 7,008 participants (without dementia) were asked each time whether they had a history of anesthesia – including general anesthesia or local/locoregional anesthesia since the previous follow up. The researchers adjusted the data to factor in possible confounders, such as comorbidities and socioeconomic status.

Sixty-two percent of the participants were female and their average age was 75 years.

Below are some highlighted data from the study:

At the 2-year follow up 2,309 (33%) of participants had reported an anesthesia during the previous two years, 1,333 (19%) had general anesthesia (GA) and 948 (14%) had local/locoregional anesthesia (LRA)

Over the following 8 year period, 9% (632) of the participants developed dementia, 284 of them with probable Alzheimer’s disease (AD) and 120 with non-Alzheimer’s dementia

37% of the participants with dementia had received anesthesia compared to 32% of the others

22% of the dementia patients reported a GA versus 19% of those without dementia

After accounting for possible confounders, those with at least one GA had a 35% higher risk of developing dementia compared to the participants with recent (8-year) history of anesthesia

The researchers concluded:

“These results are in favour of an increased risk for dementia several years after general anaesthesia. Recognition of POCD is essential in the perioperative management of elderly patients. A long-term follow-up of these patients should be planned.”

Anesthesia exposure has not only been found to affect the brains of older people. Scientists from the Mayo Clinic reported in Mayo Clinic Proceedings (Feb 2013 issue) that children exposed to anesthesia many times have a higher risk of developing ADHD (attention-deficit/hyperactivity disorder).

Written by Christian Nordqvist