-- Mary Elizabeth Dallas
FRIDAY, Sept. 30 (HealthDay News) -- New research adds to the
growing evidence that anesthesia and surgery may be associated with
the progression of chronic brain diseases, particularly Alzheimer's
"We have long sought a clearer picture of the true impact of anesthesia and surgery on the central nervous system," study author Dr. Roderic Eckenhoff, the Austin Lamont Professor of Anesthesia at the Perelman School of Medicine at the University of Pennsylvania, said in a university news release.
"Although not definitive, this human biomarker study gives some credibility to the notion that anesthesia and surgery produce an inflammatory insult on the brain and accelerate chronic neurodegenerative diseases like Alzheimer's," Eckenhoff added.
In conducting the study, which is published in the October issue
of the journal
Anesthesiology, researchers collected cerebral spinal fluid from 11 patients both before and in four intervals after routine endoscopic nasal surgery.
The researchers explained that there are "biomarkers" (or
indicators) for Alzheimer's disease found in cerebral spinal fluid.
Measuring these indicators, known as amyloid beta and tau protein,
can help detect Alzheimer's before symptoms appear and help predict
which patients will progress from mild cognitive impairment to
full-blown Alzheimer's disease.
High levels of tau protein and decreased amyloid beta are
generally considered signs of Alzheimer's, the researchers pointed
out in the news release.
Although average amyloid beta concentrations varied by less than
10 percent in either direction and remained unchanged in the 48
hours following surgery, the investigators found significant
increases in total tau six hours after surgery. This level
continued to rise 48 hours after the operation.
An injury biomarker and three inflammatory biomarkers were also
significantly increased over time after surgery, the study showed.
Overall, the findings suggest that the changes in the cerebral
spinal fluid biomarkers are in line with Alzheimer's disease
The researchers noted that the use of sevoflurane -- one of the
most widely used inhaled anesthetics, which may reduce immune
responses during surgery -- was associated with significantly
higher concentrations of inflammatory biomarkers than other
More research is needed, however, to determine if the management
of anesthetics could make a difference in neuroinflammation
following surgery, the study authors pointed out.
"The evidence for anesthesia per se being responsible for the changes we saw in this study is not definitive -- in fact, our work in animal models of Alzheimer's is beginning to suggest that the surgical procedure itself produces a larger effect than anesthesia," said Eckenhoff. "The next step in this line of research is to determine whether anesthetic management can modulate the neuroinflammation caused by surgery, whether this brief inflammatory insult can actually change the trajectory of something like Alzheimer's disease, and given that surgery is usually not strictly elective, development of a strategy to reduce the inflammatory insult to the brain."
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