There is strong evidence that traumatic brain injury (TBI) increases the risk of developing dementia. The risk of developing dementia is greatest among people who have suffered multiple TBIs. But even a single TBI can increase the risk of dementia, slightly.
How serious is traumatic brain injury?
TBI has a wide range of severity. The condition extends from a mild concussion, from heading a soccer ball (football) too hard or getting an elbow to the head in a basketball game with no loss of consciousness, for example, all the way to a devastating brain injury that results in coma or fatality.
The Centers for Disease Control estimate that 1.74 million people in the United States seek medical help for a traumatic brain injury every year, and 200,000 of them are admitted to the hospital.
While TBIs related to sports injuries make the headlines, the majority of traumatic brain injuries in the USA occur during moving vehicle accidents. These include cars, trucks, motorcycles, bicycles, skate boards, and more exotic forms of transportation. In the US, moving vehicle accidents account for over 50 percent of brain injuries. Falls account for another 20 to 30 percent of TBIs, and are the leading cause of this injury in young children and in adults over the age of 70. (In the UK, the greatest numbers of TBIs are caused by falls and assaults, and then moving vehicle accidents).
Men are more likely to experience TBI than women. In the US, firearms are associated with a majority of TBIs in people aged 25 to 34. In the military, most TBIs are combat-related, and alcohol is a factor in many brain injuries. Most traumatic brain injuries do not occur while playing sports.
When the Danish scientists looked at the relationship between TBI and dementia, they found that:
- Having five or more TBIs was linked to a 300 percent increase in risk of dementia.
- Having any TBIs at all was linked to a 24 percent increase in risk of dementia.
- Having only one "mild concussion" correlated to a 17 percent increase in risk.
So, does this mean that if you have concussion, you are doomed to getting dementia? Not at all. The risk of early-onset dementia, by age 50, is very low. TBI just makes a low risk of dementia a little higher. Furthermore, the greatest risk of developing dementia occurred in the first six months following the injury. That seems to imply that if you have a TBI, and you don't develop dementia right away, and you start taking steps to prevent future head injuries, you may not have an increased risk of long-term neurocognitive impairment.
And that 300 percent increase in the risk of developing dementia? Among Danes, 4.5 percent of the population eventually develops dementia. In absolute terms, that means people who have more than five TBIs have about a 13.5 percent risk of developing dementia. That risk is not to be ignored, especially when you are planning healthcare for an entire nation, but to the individual, there is no reason on the basis of statistics alone to be afraid of losing your mind.
Who really does have a risk of developing dementia as a result of TBI?
Dr Steven Kornguth of the University of Texas at Austin says that what makes the difference between long-term recovery and long-term disability is the resilience of the immune system. Chronic brain inflammation results when a series of injuries triggers the production of antibodies that keep responding to the injury to the brain. TBI damages white matter throughout the brain, unlike other causes of dementia that target specific parts of the brain. Monitoring changes in the volume of the white matter of the brain, which Kornguth has seen in female soccer (football) players as young as 18, and looking for tiny hemorrhages in the brain, predict the long-term changes that interfere with problem solving, coordination, and attention. And because this disease process is controlled by the immune system, treating the immune system, not just the brain, should prevent dementia.
Dr Kornguth's work with elite soldiers and women athletes suggests that something as simple as an antibiotic (Dr Kornguth has explored the use of minocycline, better known as an acne medication) can alter the destructive autoimmune processes that destroy the white matter of the brain. Any elite athlete (who has the athletic skills to generate the power that does damage to the brain) should be followed by a neurologist to detect early deterioration and to start early intervention as the scientific understanding of TBI and brain health unfolds.