Sustaining a traumatic brain injury (TBT) in your 20s may increase the risk of developing dementia including Alzheimer's in your 50s by 60 percent, a review of almost three million patients has revealed.
The authors say the findings are concerning and more needs to be done to prevent these types of injuries as a way of reducing the burden of dementia on society.
A single severe TBI increased the risk of dementia by 35 per cent, while one mild TBI (concussion) increased the risk by 17 per cent.
T.B.I. has a wide range of severity.
SUFFERING concussion just once in a lifetime has been linked to an increased risk of both dementia and Alzheimer's disease.
Findings from a review of almost 2.8 million patient cases in Denmark were published April 10 in The Lancet Psychiatry. About 95 per cent of people who suffered a brain injury never developed dementia.
After adjusting for medical, neurological and psychiatric illnesses, they found that compared with people who had never had a T.B.I., those who had had any were at a 24 percent increased risk for dementia, and those who had had five or more had almost triple the risk.
Despite the size of the studies, they won't settle scientific questions - or social debate - about brain injuries from sports, war, auto crashes or domestic violence.
A traumatic brain injury occurs when an external force such as a bump or blow to the head disrupts the normal function of the brain.
The scientists involved in the brain injury and dementia research identified every diagnosis of TBI from the health records of a Danish population of 2.8 million people between 1977 and 2013. Leading causes include falls, motor vehicle accidents, and assaults. He warns parents and children to be well-aware of risks of TBIs in contact sports.
In a commentary in the journal, Dr. Carol Brayne of University of Cambridge's medical school in England wrote that improvements in care mean more people are surviving brain injuries, making it crucial to understand more about their long-term effects. "The attributable risk of traumatic brain injury to different exposures and how these change across time needs policy attention, given it is likely that prevention of these need be considered at societal, community, and local levels".