People who have had a traumatic brain injury (TBI) are at greater risk for dementia than people who have never sustained a TBI or who have had trauma that doesn’t involve the brain or spine, according to a new study published online in Lancet Psychiatry on April 10.
Despite the prevalence of dementia and ubiquity of TBI, previous studies have been inconclusive regarding the link between them. Studies that showed a link couldn’t be duplicated, probably because of limited access to large sample sizes and minimal follow-up time.
To measure the effect of brain injury on dementia risk, the researchers looked at nationwide data for more than 2 million Danish citizens who were at least 50 years old during the follow up. They gathered information on the time and severity of brain traumas, when people showed signs of dementia, and whether they had other medical, psychiatric, and neurological diseases. Of this group, roughly 132,000 had at least one TBI between 1977 and 2013 and about 126,000 developed dementia between 1999 and 2013.
The researchers found that people are most at risk for dementia in the
first six months after their brain trauma, and their risk increases if they
sustain another TBI. In addition, the younger a person was when sustaining a
TBI, the higher the risk of dementia later in life. In elderly people, a TBI
was less likely to contribute to, probably because the elderly have more
exposure to other factors that are thought to cause dementia.
This large, population-based study highlights the importance of preventing and treating brain trauma, particularly among young people. The researchers encourage other investigators to explore how brain trauma might cause dementia and to look for potential solutions.