A new study has revealed a startlingly high number of former football players had chronic traumatic encephalopathy (CTE) at the time of their deaths, including 110 of 111 NFL players tested.
In the study, Dr. Ann McKee of Boston University School of Medicine and a team of researchers tested 202 deceased football players (including 111 NFL players) who had donated their brains for research. Dr. McKee found that 87% of all players tested had CTE, but 99% of those who had played in the NFL had it. While the results are likely skewed because players with symptoms are more likely to donate their brains for research, they are still alarming and suggest that contact sports carry serious brain health risks.
What is CTE?
Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative condition associated with head trauma. Simply put, it causes damage to brain cells that results in cell death and worsens over time. Early symptoms of CTE fall into two broad categories: (1) behavioral and mood changes such as anxiety, depression, and issues with impulse control, and (2) cognitive impairment including memory loss. But as it develops, CTE can lead to worsening dementia and death. It was first identified in boxers in the 1920s as “punch-drunk” dementia and then “dementia pugilistica,” and its underlying pathology was described in 1973. The brains of those with CTE are marked by atrophy (i.e., shrinkage) and tau threads and tangles, which are also present in varying forms in the brains of those with Alzheimer’s and frontotemporal dementia (FTD). Because of this, CTE may be a risk factor for Alzheimer’s and FTD, though research has not yet confirmed this.
Since 1973, CTE has been diagnosed in boxers, wrestlers, military veterans, and baseball, football, ice hockey, rugby, and soccer players. Though Dr. McKee’s study found that CTE pathology was more severe in professional football players, it was still present in those who had only played at the high school or college level. A 2015 report on the brain health risks of youth sports co-sponsored by the Alzheimer’s Drug Discovery Foundation (ADDF) also found that children who played contact sports were at risk of developing CTE later in life.
Current Players
Dr. McKee’s study looked at the brains of deceased players because CTE can only be conclusively diagnosed at autopsy. But efforts are underway to develop diagnostic tools for living patients. The ADDF is funding Sam Gandy, MD, PhD, at the Icahn School of Medicine at Mount Sinai for one such project. Dr. Gandy is using 18F-AV-1451, a PET imaging agent being developed by Avid Pharmaceuticals, to try to image tau tangles and threads in the brains of people who have sustained multiple head injuries. (Dr. Gandy is testing boxers, former NCAA athletes, military veterans, and law enforcement officers.) If the project is successful, tau PET scans could be used to diagnose CTE in living patients with a history of head injuries. It could also be used to assess CTE risk in younger players by detecting the presence of tau in the brain after a head injury.
At Harvard Medical School, Neil Vasdev, PhD, is also working on a tau imaging program with support from the ADDF. Dr. Vasdev is using 18F-MK-6240, a PET imaging agent created by Merck that binds to tau deposits in the brain in a different way. He and his team are testing their PET scan in patients with mild cognitive impairment or Alzheimer’s disease. Having multiple diagnostic tools is important for differentiating between the multiple diseases that involve tau. Eventually, such scans could also help establish a link between CTE and Alzheimer’s or frontotemporal dementia.
Possible Treatments?
The ADDF is funding tau PET scan projects because accurate diagnosis of CTE in living patients is necessary to accelerate effective drugs to treat it. There are already several treatments targeting tau in clinical trials for Alzheimer’s and FTD, including projects from AbbVie, Genentech, and Eli Lilly. But their chances of success and ability to recruit the right patients will be greatly improved with tau diagnostics. It’s critical to understand what kind of tau—and therefore, which disease—a patient has they can test a treatment designed specifically for it.
While this new study of CTE provides important insights, the ADDF is working on the next steps. Our mission is to ensure that every dementia patient, including those with CTE, can get an accurate diagnosis and has effective treatment options.