Researchers have discovered that common inhaled anesthetics increase the number of amyloid plaques in the brains of animals, which might accelerate the onset of neurodegenerative diseases like Alzheimer's.

Roderic Eckenhoff, MD, Vice Chair of Research in the University of Pennsylvania's Department of Anesthesia and Critical Care, and his co-authors, report their findings in the March 7th online edition of Neurobiology of Aging.

Every year over 100 million people undergo surgery worldwide, most under general anesthesia with an inhaled drug. These drugs clearly affect cognitive ability at least in the short term, but the growing concern is that inhaled anesthetics may affect a person well beyond the perioperative period, even permanently. Several factors appear to play a role in this subtle loss of cognitive ability, most notably age.

A specific effect of these drugs on dementias like Alzheimer's disease, though suspected for many years, has only been recently supported by data. In 2003, Eckenhoff's group showed that the inhaled anesthetics enhance the aggregation and cytotoxicity of the amyloid beta peptide. Just last month, a study reported that these drugs also enhance the production of amyloid beta in isolated cells. But these protein and cell culture studies are a long way from showing that an effect occurs in vivo. This new study provides the first evidence that the predicted effect occurs in animals.

"This animal study data suggests that we have to at least consider the possibility that anesthetics accelerate certain neurodegenerative disorders," said Eckenhoff. "In the field of Alzheimer's research, most effort is focused on delaying, not curing the disease. A delay in the onset of Alzheimer's disease of only three to five years would be considered a success. Therefore, if commonly used drugs, like anesthetics, are accelerating this disorder, even by a few years, then a similar success might follow even small changes in the care of the operative patient."