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Researchers find evidence of neuron death and amyloid-beta plaques after use of isoflurane

The commonly used anesthetic isoflurane can lead to the death of brain cells and the production of amyloid-beta plaque, a hallmark of Alzheimer’s disease, according to a Harvard University research report.
The study in the January 2007 issue of the Journal of Gerontology raises questions about the safety of isoflurane, which has been used for years for all ages of patients. If the findings are proven accurate it could point to a major medical source for common symptoms of delirium, a symptom of Alzheimer’s and related mental problems.

In experiments with cells that had an amyloid-beta protein, researchers exposed them to isoflurane for six hours. They found that isoflurane caused these cells to die. “It also caused the cell to overproduce the toxic molecule responsible for the pathology of Alzheimer’s disease, particularly amyloid-beta,” said lead researcher Rudolph Tanzi, a professor of neurology at the Genetics and Aging Research Unit of the Massachusetts General Institute for Neurodegenerative Disease.

Wouldn’t let mother have it

“A big dose of isoflurane mimics a stroke or a bang to the head, and you don’t want that as a risk factor for Alzheimer’s disease at any age,” Tanzi said. “Many people who have anesthesia, especially the elderly, suffer from postoperative cognitive dysfunction, scrambling and delirium that can last six hours or two weeks or months.”

Tanzi believes that isoflurane should be avoided. “We don’t have enough data yet to ban isoflurane,” he said, “but I’m convinced enough that I won’t let my mother have it. I would advise any family or friends to stay away from isoflurane.

“There is a lot of speculation here, and a lot of work needs to be done, but at this point I wouldn’t take a chance,” he added. “Any trauma to the brain induces cell death. Isoflurane now joins that list of insults to the brain that can cause cell death and excessive production of this key molecule in Alzheimer’s pathology. Thisdoes increase the risk for Alzheimer’s disease.”

Delirium: a $100 billion problem

Delirium is probably the single most common acute disorder affecting adults in general hospitals. It affects 10-20% of all hospitalized adults, and 30-40% of elderly hospitalized patients.

In the United States, delirium accounts for $7 billion per year in hospital expenses and more than $100 billion a year when rehabilitation, institutionalization and long-term care are added to the equation.

Delirium itself is not a disease, but rather a clinical syndrome (a set of symptoms), which results from an underlying disease or new problems with thinking and awareness. Like its components –– inability to focus attention and various impairments in awareness and temporal and spacial orientation –– delirium is simply the common symptomatic manifestation of early brain or mental dysfunction for any reason.

“This is a warning,” Tanzi said. “Isoflurane may be one reason why the elderly are more prone to cognitive dysfunction following anesthesia.”

Source: National Institutes of Health, Medlineplus.com, Jan. 15 (HealthDay News)