The study, which was funded by the U.S. National Institutes of Health and released Wednesday, is to be presented at the American Academy of Neurology's annual meeting, from April 25 to May 2, in Seattle.
But the findings should not send people scurrying for genetic testing, Seshadri and another expert said.
Alzheimer's is "not like Huntington's, where if you have the bad gene and you live long enough you're going to get it," Seshadri said. "E4 explains only part of the risk. Clearly there are other genes out there, but they probably have much smaller effects than ApoE4."
Dr. Gary J. Kennedy, director of the division of geriatric psychiatry at Montefiore Medical Center in New York City, said that the finding "needs to be seen with considerable caution so it doesn't get over interpreted."
For starters, he said, the study has not been peer-reviewed, meaning it has not been scrutinized and evaluated by other experts in the field, a process that precedes publication of research in a major medical journal.
Also, statistics in the abstract of the study do not indicate how big a risk factor carrying the ApoE4 gene is for those whose parents had dementia or Alzheimer's, Kennedy said, and the brain scans of the study participants did not show any volumetric changes. "If they saw volumetric changes, that would be scary," Kennedy said.
The bottom line then, according to Seshadri, is that 50-somethings who begin to lose their car keys don't need to start worrying as a result of this study.
"Those of us who lose our keys actually have pretty good memories," she said. "We remember we lost our keys." Besides, she said, people lose their keys "mainly because we were thinking of 15 other things when we put our keys down."<
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