Concussions Linked to Alzheimer's Risk in Study
Brain scans found seniors with both poor memory and prior head injury have more plaque buildup
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Among those with mild cognitive impairment, those with concussion histories had a nearly five times higher risk of elevated plaque levels than those without a history of concussion.
The researchers don't know why some with concussion history develop memory problems and others do not.
The research was funded by the U.S. National Institutes of Health, among several other supporters.
The study adds valuable information for experts in the field, said Dr. Robert Glatter, director of sports medicine and traumatic brain injury in the department of emergency medicine at Lenox Hill Hospital, in New York City. Glatter, who is also a former sideline physician for the National Football League's New York Jets, reviewed the new study findings.
Other studies, he said, often rely on postmortem information. In the Mayo study, participants had to have loss of consciousness as a measure of having a concussion history, Glatter noted. However, he added, the new thinking is that loss of consciousness is not necessary to define a concussion -- one can occur without that.
The effect of head injury may be cumulative over time in the development of Alzheimer's, he said. In the past, experts thought only severe head trauma was linked with Alzheimer's, but less severe injury may actually be relevant as well, he added.
Some other factor or factors yet to be discovered may be at play, Glatter said.
Both Mielke and Glatter stressed that concussions don't automatically lead to Alzheimer's. "Not all people with head trauma develop Alzheimer's," Glatter said.
"If you do hit your head, it doesn't mean you are going to develop Alzheimer's," Mielke said, although "it may increase your risk."