A new study by Boston University researcher Dr. Ann McKee examined the brains of 202 deceased football players and found that 110 of the 111 brains of former NFL players had chronic traumatic encephalopathy (CTE). The results were published the Journal of the American Medical Association.
The brains were donated by families of former NFL players who showed signs of the disease. The study was not conducted on a set of random former NFL players, and Dr. McKee notes "tremendous selection bias" in the samples.
“It is no longer debatable whether or not there is a problem in football—there is a problem,” Dr. McKee said, according to the New York Times.
High school players in the study had mile cases while college and professionals had more severe cases. CTE was found in 177 of the 202 brains.
The disease can cause impaired judgment, aggression, memory loss and depression. CTE can only be diagnosed postmortem.
The study examined players as young as 23 years old and as old as 89. The brains were also from all player positions including 44 linemen, 10 linebackers, 17 defensive backs and seven quarterbacks.
Former NFL Hall of Famer Ken Stabler was among the brains after he asked that he be examined when he was battling colon cancer. McKee determined that Stabler had a "moderately severe" case of CTE.
The family of the only NFL player without CTE did not authorize for Dr. McKee to publicly identify him.
The NFL issued the following statement to SI.com:
"We appreciate the work done by Dr. McKee and her colleagues for the value it adds in the ongoing quest for a better understanding of CTE. Case studies such as those compiled in this updated paper are important to further advancing the science and progress related to head trauma. The medical and scientific communities will benefit from this publication and the NFL will continue to work with a wide range of experts to improve the health of current and former NFL athletes. As noted by the authors, there are still many unanswered questions relating to the cause, incidence and prevalence of long-term effects of head trauma such as CTE. The NFL is committed to supporting scientific research into CTE and advancing progress in the prevention and treatment of head injuries.
In 2016, the NFL pledged $100 million in support for independent medical research and engineering advancements in neuroscience related topics. This is in addition to the $100 million that the NFL and its partners are already spending on medical and neuroscience research."
Last year, Jeff Miller, the NFL's senior vice president for health and safety, testified before the House of Representatives and was asked by Illinois congresswoman Jan Schakowsky whether he thinks “there is a link between football and degenerative brain disorders like CTE.”
“The answer to that question is certainly yes,” Miller responded.