Anesthesia, Surgery Linked to a Doubling of Dementia Risk

Caroline Cassels

August 01, 2013

Older patients who undergo anesthesia and surgery have a significantly increased risk for dementia, a large population-based study shows.

Investigators at Taipei Veterans General Hospital in Taiwan found that patients older than 50 years who underwent anesthesia for the first time had nearly a 2-fold increased risk for dementia, mainly Alzheimer's disease, compared with nonanesthetized patients.

"The results of our nationwide population-based study suggest that patients who undergo anesthesia and surgery may be at increased risk of developing dementia. Anesthesia and surgery are inseparable in clinical settings. Thus, it is difficult to establish whether the increased risk of dementia development we observed was attributable to the anesthesia per se, the surgical process, or both," principal investigator Jong-Ling Fuh, MD, said in a statement.

The study was published online July 25 in the British Journal of Psychiatry.

Although generally considered safe, there is growing concern that anesthetic drugs may have neurodegenerative complications.

The investigators point out that in vivo studies and imaging studies have shown that "inhaled anesthetic agents can promote amyloid β peptide (Aβ) peptide oligomerisation and enhance Aβ-induced neurotoxicity."

Other potential mechanisms of anesthetic-induced neurotoxicity include calcium dysregulation.

The researchers note that postoperative confusion/decline is generally thought to be short-lived, with normal cognition returning within a few days. However, they add that in some cases, it can last for weeks.

Using data from the Taiwan National Health Insurance Research database, the researchers retrospectively examined whether the risk for dementia increased after surgery with anesthesia. They also looked at possible associations among age, mode of anesthesia, type of surgery, and risk for dementia.

The study cohort included 24,901 patients aged 50 years and older who were anesthetized for the first time since 1995 between January 1, 2004, and December 31, 2007, and a control group of 110,972 randomly selected age- and sex-matched patients. All participants were followed until December 31, 2010, to identify the emergence of dementia.

During the 2- to 7-year follow-up period, 661 of 24,901 anesthetized patients (2.65%) and 1530 of the 110,972 nonanesthetized patients (1.39%) were diagnosed with dementia, equating to a nearly 2-fold increased risk for dementia in the anesthesia/surgery group (hazard ratio, 1.99; 95% confidence interval, 1.81 - 2.17).

"Although anesthesia and surgery have provided immeasurable health and social benefits, our observations in this piece of research highlight the need for further studies to understand the association and causality between anesthesia with surgery and subsequent dementia," said Dr. Fuh.

The authors report no relevant financial relationships.

Br J Psychiatry. Published online July 25, 2013. Abstract


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