You may have already heard about how concussions and other head injuries can affect athletes in high-contact sports like rugby or football.
Durham University says rugby players who’d gotten five or more concussions were almost twice as likely to experience depression, anxiety, and irritability than those with fewer head injuries.
Researchers have also linked head injuries to dementia, though it’s hard to prove it definitely causes the condition.
But recent research from Oxford’s Institute of Population Ageing, Tufts University, and the University of Manchester has found that the damage may be linked to dementia for reasons you might never have suspected.
Why might head injuries cause dementia?
According to the paper, which was published in the journal Science Signalling, knocking your head might activate a virus which would otherwise lie dormant in your brain.
They used bioengineered human brain tissue models, creating concussion-like injuries to see what would happen to it.
The scientists found that HSV-1, which gives you cold sores (cold sores have been linked to dementia before), reactivates after the blows if it was dormant.
The virus can lay low in a human’s cells for a lifetime, but when it was reactivated in this study, it created changes that were similar to those you’d expect to see as a dementia patient’s condition develops (amyloid plaque-like formations (PLFs), gliosis, neuroinflammation, and decreased functionality).
Interestingly the researchers found that blocking an inflammatory molecule called Interleukin-1 seemed to prevent the risk.
“Head injuries are already recognised as a major risk factor, as are the cumulative effect of common infections, for conditions such as Alzheimer’s and dementia, but this is the first time we have been able to demonstrate a mechanism for that process,” Professor Ruth Itzhaki, who led the research, said.
“What we’ve discovered is that in the brain model, these injuries can reactivate a dormant virus, HSV1, setting off inflammation which, in the brain, would lead to the very changes we see in Alzheimer’s patients.”
Does that mean concussions will definitely give me dementia?
Not necessarily; this was done on 3D brain models rather than actual humans, and it only showed a pattern which was associated with dementia.
I can’t think of an ethical way to have a human trial for this (you can’t go ’round giving people concussions and seeing what happens), but the fact that it wasn’t done on real people may prove a limitation.
Alzheimer’s Society writes, “More research needs to be done to understand how the type and frequency of the injury, and age of the individual influences the risk of dementia.”
Still, there’s a lot of research to suggest bashing your head isn’t great for your brain.
And as Dr Itzakhi says, ”’Understanding both the risk factors for dementia and Alzheimer’s, and the mechanism by which they develop, is important in being able to target treatment and prevention at as early a point as possible.”
Here’s hoping this research leads to better, and earlier, dementia interventions.