Using an experimental PET scan, researchers have found elevated amounts of abnormal tau protein in brain regions affected by chronic traumatic encephalopathy (CTE) in a small group of living American (NFL) players with cognitive, mood and behavior symptoms (Stern RA et al. Tau Positron-Emission Tomography in Former National Football League Players. N Engl J Med. 2019 May 2;380 :1716. doi: 10.1056/NEJMoa1900757).
The researchers also found that the more years of tackle football played (across all levels of play), the higher the tau protein levels detected by the PET scan.
However, there was no relationship between the tau PET levels and cognitive test performance or severity of mood and behavior symptoms.
CTE is a neurodegenerative disease that has been associated with a history of repetitive head impacts, including those associated with concussion symptoms in American football players. At the moment, CTE can only be diagnosed after death by a neuropathological examination, Like Alzheimer’s disease (AD), CTE has been suggested to be associated with a progressive loss of brain cells. In contrast to AD, the diagnosis of CTE is based in part on the pattern of tau deposition and a relative lack of amyloid plaques.
Results showed that the tau PET levels were significantly higher in the former NFL group (26 players) than in the controls (31 same age men) and the tau was seen in the areas of the brain which have been shown to be affected in post-mortem cases of neuropathologically diagnosed CTE.
Interestingly, the former player and control groups did not differ in their amyloid PET measurements.
“Our findings suggest that mild cognitive, emotional, and behavioral symptoms observed in athletes with a history of repetitive impacts are not attributable to AD, and they provide a foundation for additional research studies to advance the scientific understanding, diagnosis, treatment, and prevention of CTE in living persons”, said co-author Dr. E Reiman,
doi: 10.1056/NEJMoa1900757.