In American football, players repeatedly suffer major blows to the head. As a result of these repeat hits, many athletes suffer from chronic traumatic encephalopathy (CTE), a degenerative brain disease that manifests as depression, dementia, aggression and suicidal behavior years to decades after the trauma.

But the researchers behind a new study say that a single traumatic brain injury can also have lasting consequences on brain health. A team of scientists from Europe found that levels of a protein called tau, which marks brain injury in CTE, also shows up in patients that had a single traumatic brain injury. The researchers say the discovery may lead to earlier therapeutic interventions for patients.

“It is important to be able to detect tau in the brain during a person’s lifetime, as this in the future might lead to timely treatment to slow down dementia in this vulnerable patient population,” Imperial College London neurologist Nikos Gorgoraptis, who authored the new research, said in an email.

Tau Trauma

Experts increasingly recognize that traumatic brain injuries are putting people at risk for neurodegeneration and dementia. Recent studies of deceased National Football League players’ brains showed those with CTE had accumulated tau clumps, a feature of other well-known neurodegenerative diseases like Alzheimer’s. But until recently, researchers had no way of detecting the hallmark protein in living patients.

“This is very important, as detecting tau during a person’s lifetime can help diagnosis and prognostication,” Gorgoraptis said.

In the new study, Gorgoraptis and colleagues examined tau accumulation in 21 living patients who had suffered a single traumatic brain injury in a car accident, assault or fall from a meaningful height many years prior. When they looked inside the patients’ brains, scientists uncovered the protein by injecting a molecule that attaches to tau. The molecule emits radiation that special sensors can pick up.

Taking Time

The scans revealed about two-thirds of TBI patients had elevated levels of tau in their brains in comparison to healthy subjects of the same age. But the amount of tau varied from patient to patient. About a third of TBI patients had extensive increases in tau, but another third showed no abnormality. The final third’s tau levels landed in the middle the researchers report Wednesday in the journal Science Translational Medicine.

Although the researchers saw the same kinds of tau accumulations that are present in the brains of people with Alzheimer’s disease, the tau masses piled up in different parts of the brain in TBI patients than those with Alzheimer’s. The finding also suggests the pattern of tau accumulation may help diagnose the type of neurodegeneration a patient suffers from.

And, for both Alzheimer’s and CTE, detecting these build-ups in living patients opens the door for future clinical trials that could clear tau from the brain, or even just slow down tau-related dementias. But the biggest boon is time.

“Our findings … pave the way towards detecting tau after traumatic brain injury when it really matters – as early as possible during their lifetime,” Gorgoraptis said.