Florida eye exam gets results
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Excerpts from the Globe's blog on the Boston-area medical community.
Older drivers account for more motor vehicle collisions per mile than other age groups. Some states - not Massachusetts - have raised the bar for older drivers to stay on the road. Since 2004, Florida has required drivers who are 80 and older to pass an eye test before renewing their licenses.
To see if the law made a difference, University of Alabama researchers compared fatality rates for three years before and after it went into effect. They report the results in the Archives of Ophthalmology.
While overall deaths went up 6 percent after the Florida law took effect, deaths went down 17 percent among drivers 80 and older.
The authors say the lower death rate may have been caused by older drivers deciding not to renew their licenses, getting treatment to improve their vision if they didn't pass the test, or failing the test and giving up their keys.
Massachusetts has no testing requirements for older drivers. Doctors and family members are encouraged to report drivers who they think might pose a hazard.
Dr. Zhongcong Xie and his colleagues at the Mass. General Institute for Neurodegenerative Disease had already seen how, in laboratory tests, isoflurane spurred production of amyloid-beta protein - the brain plaque in Alzheimer's disease.
As a next step, the researchers gave mice doses of isoflurane equivalent to what people would receive.
After six hours, the anesthetized mice showed signs that programmed cell death was beginning, and levels of an enzyme that makes amyloid-beta protein were rising.
After 24 hours, the enzyme was four times higher in those mice than in untreated mice, supporting the idea that the anesthetic not only triggers cell death but also spurs excessive production of amyloid-beta protein.
"It may put elderly patients at risk for Alzheimer's disease if - and it's a very big if - this happens in humans under conditions of surgery. You could be triggering disease or exacerbating disease," Rudolph E. Tanzi, the paper's senior author and director of the Genetics and Aging Research Unit at Mass. General, said in an interview.
Research is mixed on isoflurane, with some studies saying it's better than other agents in cardiac bypass surgery.
Tanzi recommends caution: "Even though I say it's too early to say anything to the operating room or to anesthesiologists about isoflurane, we just don't know. For family and friends, I say don't risk it. Just use another agent."
ELIZABETH COONEY
