Leaving a Mark on the Brain

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Repeated concussions in former athletes linked to high levels of tau protein.
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The National Football League (NFL) reported that its players sustained at least 214 concussions during games and practices in the 2018 season.

Concussions are a common type of injury in contact sports, such as football and hockey. They are caused by a blow or jolt to the head or body that damages the brain.

Athletes with a history of repeated concussions are at an increased risk of developing a neurodegenerative condition known as chronic traumatic encephalopathy (CTE). The condition impairs mental function and memory and can cause behavioural changes, such as aggression or depression.

“We do not fully understand how CTE develops or why it develops in some people with multiple concussions but not others. Diagnosing the condition is also a challenge because many of its symptoms overlap with those of other neurodegenerative diseases, such as Alzheimer disease,” says Dr. Carmela Tartaglia, a Clinician Investigator at Krembil Research Institute.

To begin addressing these gaps in knowledge, a team of researchers led by Dr. Tartaglia recently published a study examining 22 former professional athletes—including hockey and football players, as well as a snowboarder—who sustained multiple concussions throughout their careers.

The researchers measured the levels of total tau and beta-amyloid proteins in the cerebrospinal fluid of each athlete. These proteins are frequently used in the diagnosis of Alzheimer disease. The researchers also assessed the athletes’ brain structure using magnetic resonance imaging and brain function through neuropsychological tests.

They discovered that the former athletes could be divided in two groups based on their total tau levels: one group had significantly higher tau in their cerebrospinal fluid than healthy participants without a history repeated concussions, whereas the other group had levels comparable to those in healthy participants. The researchers also found that athletes in the high tau group displayed impairments in their mental function and changes in their brain structure, both of which are indicative of neurodegeneration.

“Our findings suggest that high total tau levels could be a sign of neurodegeneration in individuals who have sustained multiple concussions,” says Dr. Tartaglia. “Detecting evidence of neurodegeneration is the first step towards being able to provide a treatment. Not everyone with multiple concussions gets CTE or other neurodegenerative diseases, so being able to detect those with evidence of disease is important for targeting treatment to the right person.”

This work was supported by the PSI Foundation, the Canadian Institutes of Health Research, and the Toronto General & Western Hospital Foundation. Dr. Tartaglia holds the Marion and Gerald Soloway Chair in Brain Injury and Concussion Research.

Taghdiri F, Multani N, Tarazi A, Naeimi SA, Khodadadi M, Esopenko C, Green R, Colella B, Wennberg R, Mikulis D, Davis KD, Goswami R, Tator C, Levine B, Tartaglia MC. Elevated cerebrospinal fluid total tau in former professional athletes with multiple concussions. Neurology. 2019 Jun 4. doi: 10.1212/WNL.0000000000007608.

Dr. Carmela Tartaglia, Clinician Investigator, Krembil Research Institute.