Neurology Central

Tau biomarker linked to chronic traumatic encephalopathy in former athletes

In a study focused on a group of former professional athletes who have experienced multiple concussions, over half the group were reported to have higher levels of tau protein biomarkers in their cerebrospinal fluid.

A study involving a group of former athletes who have experienced multiple concussions have been tested for the quantity of tau protein in their cerebrospinal fluid and approximately half of the group were reported to have elevated levels. The study will be published today in the online issue of Neurology.

The research team also explained that the athletes with elevated levels of tau scored lower on a test measuring thinking skills, compared with the athletes with normal tau levels. Furthermore, brain scans suggested that the white matter in their brains was not as healthy in athletes with higher levels of tau.

“Previous research has shown a link between former professional athletes who suffer multiple concussions and a diagnosis of chronic traumatic encephalopathy (CTE) after death, however we wanted to find a marker of CTE that can be measured while someone is still alive and then see if it related to loss of brain function,” explained Maria Carmela Tartaglia (University of Toronto; Canada). “Tau has been linked to a higher risk of CTE in the past and our study found higher levels of this protein in the cerebrospinal fluid of some of the former athletes.”

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The research included 22 Canadian male former professional athletes with a history of multiple concussions and an average age of 56 years, including one snowboarder, nine hockey players and 12 Canadian Football League players. The control groups included 12 people with Alzheimer’s disease and five healthy individuals.

The participants underwent testing to determine the levels of tau in their cerebrospinal fluid, along with brain imaging scans, examinations and tests of thinking, decision-making and memory.

The research team found that 12 (54%) out of 22 athletes had elevated levels of tau. The athletes with elevated levels of tau were found to have higher levels than the healthy group, but lower levels of tau compared with the group associated with Alzheimer’s disease. More than 300 picograms per milliliter (pg/ml) was considered as high levels of tau. Healthy participants had levels of 188 pg/ml, the athletes had levels of 349 pg/ml and people with Alzheimer’s disease had levels of 857 pg/ml.

In the cognitive functioning tests the athletes with high tau levels scored lower than the athletes with normal levels, with scores of 46 and 62.

“The findings support the idea that multiple concussions or head impacts put some people at risk of developing neurodegeneration which is the progressive loss of nerve cells, and possibly CTE, and this may be detected by measuring cerebrospinal fluid tau. It also highlights the importance of finding a biomarker of CTE that can be measured while someone is alive, since currently a CTE diagnosis can only be determined in an autopsy, and not all players who suffered multiple concussions had elevated tau,” explained Tartaglia.

Limitations of the group included the small sample size and the lack of woman in the former athletes group.