Anesthesia and Alzheimer's Link

By Lucy Williams, Ivanhoe Health Correspondent

ORLANDO, Fla. (Ivanhoe Newswire) -- A common anesthetic may induce biomarkers of Alzheimer's disease. Isoflurane (Forane), a general anesthetic inhalant, may cause cell death and generation of an Alzheimer's-associated protein, recent research reveals.

General anesthesia may increase risk for Alzheimer's disease. One biomarker of Alzheimer's disease is the presence of plaques in the brain. Amyloid-beta protein (A-beta) is toxic to brain cells and is a key component in these plaques. Apoptosis, or cell death, is another indicator of cognitive decline. Previous research revealed application of isoflurane to neural cells in a lab led to apoptosis and the generation of A-beta.

"Isoflurane can be one of the most commonly used anesthetics in operation. We use it every day," lead author Zhongcong Xie, M.D., Ph.D., of the MassGeneral Institute for Neurodegenerative Disease in Charlestown, Mass., told Ivanhoe.

Researchers at Massachusetts General Hospital in Boston applied isoflurane to cultured neural cells in a series of experiments. They reported activation of caspase, an enzyme that contributes to apoptosis. When researchers applied isoflurane to neural cells that express amyloid precursor protein (APP), which aids the formation of A-beta, isoflurane raised levels of A-beta-releasing enzymes.

Study results indicate isoflurane promotes apoptosis and the production of A-beta through specific molecular pathways. Isoflurane may also initiate a process by which A-beta generation and apoptosis interact and magnify one another.

Researchers only used cultured cells in their study. Dr. Xie said while these kinds of lab studies can give scientists a preliminary understanding of how medications affect disease, it's still too early to know if the same reactions would be seen in humans.

"This is alarming, but it's still premature to come to a conclusion," said Dr. Xie. "We need to work hard to have more data to support our hypothesis that isoflurane is toxic and facilitates dementia, or cognitive dysfunction, in humans."

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SOURCE: Ivanhoe interview with Zhongcong Xie, M.D., Ph.D.; The Journal of Neuroscience, 2007;27:1247-1254