Does Head Injury Increase Risk of Alzheimer's Disease?
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This study solved some of these problems by relying on medical records rather than patient or family reports to document head injury. By examining military records of World War II veterans hospitalized during their service for head injury, or for other conditions unrelated to head injury, the researchers found, examined, and did psychological testing on more than 500 veterans with documented head injury, and on more than 1,200 without it.
Severity of head injury was determined from how long the veteran passed out or had no memory of the injury, with mild head injury being less than 30 minutes, moderate between 30 minutes and 24 hours, and severe being longer than 24 hours.
Risk of Alzheimer's disease or of other forms of dementia was about twice as high in those with moderate head injury, and about four times as high in those with severe head injury. Mild head injury did not significantly increase risk.
"Whether prevention or better treatment of head injury could influence later development of Alzheimer's disease is an interesting question," Myron F. Weiner, MD, tells WebMD. He is a professor and vice chairman for clinical services in psychiatry at the University of Texas Southwestern Medical Center in Dallas, and reviewed the study for WebMD.
While professional boxers tend to get "punch-drunk," developing memory problems related to repeated blows to the head, this study showed that even a single moderate or severe head injury increased risk of Alzheimer's disease up to 40 to 50 years later.
"From a public health point of view, such findings add weight to the need to prevent head injury," Anthony Jorm, PhD, Dsc, tells WebMD. Countries such as Australia have laws restricting boxing and requiring the use of seat belts in cars, and helmets on motorbikes and bikes.
"These measures are justified by the suffering and disability that head injury can produce short term, but now we must add in the possibility of dementia down the track," says Jorm, professor and deputy director of the Centre for Mental Health Research at Australian National University in Canberra.