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Study Finds CTE in 99% of Deceased NFL Players

A new study investigating the brains of deceased National Football League players found signs of degenerative brain disease in 99 percent of subjects.

The progressive brain degenerative disease chronic traumatic encephalopathy (CTE) was found in 99 percent of deceased National Football League players’ brains in a new study published in JAMA.

CTE is caused by repetitive blows to the head. The disease is characterized by a buildup of abnormal tau protein in the brain, which interrupts neuropathways and inhibits cell-to-cell communication. Eventually, the brain atrophies, or wastes away, leading to degenerative symptoms like memory loss, confusion, impaired judgment, impulse control problems, aggression, and depression.

Over the years, it’s become apparent that contact-sport athletes like NFL players are at an extremely high risk of developing the disease. A 2015 study had similar results, discovering CTE in the brains of 96 percent of former NFL players. This new study demonstrating the disease’s prevalence among football players, from researchers at Boston University’s CTE Center, is the largest of its kind.

Investigators examined the donated brains of deceased former NFL players, including those publicly confirmed to have the disease. Out of 111, 110 showed signs of CTE.

“There’s no question that there’s a problem in football. That people who play football are at risk for this disease,” said Dr. Ann McKee, director of Boston University’s CTE Center and co-author of the study. “And we urgently need to find answers for not just football players, but veterans and other individuals exposed to head trauma.”

The study also examined the brains of deceased high school and college athletes who formerly played football. Out of 202, CTE was diagnosed in 177.

After the study’s findings were published, Baltimore Ravens John Urschel abruptly retired from the game, concerned about his long-term health. A few days later, New York Giants rookie Jadar Johnson also retired.

“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,” the NFL told CNN in a statement, adding that “there are still many unanswered questions relating to the cause, incidence and prevalence of long-term effects of head trauma such as CTE.”

Research findings suggest that a cannabinoid found in cannabis may be beneficial for preventing and treating brain injury disease like CTE. Studies have found evidence that the compound cannabidiol (CBD) effectively reduces brain swelling and removes the abnormal tau protein deposits that build up in the brain, thereby preventing neural damage and improving recovery.

Medical Marijuana Inc.’s portfolio company Kannalife Sciences, Inc. (“Kannalife”) is currently developing a CBD-based pharmaceutical treatment for CTE. Kannalife holds two licenses with the U.S. National Institutes of Health for U.S. Patent 6,630,507 “Cannabinoids as Antioxicants and Neuroprotectants.” These licenses are currently in use as Kannalife develops its novel CBD therapeutic drugs.

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For NFL players, the league’s strict drug policy prohibits them from incorporating cannabis or cannabinoids into their treatment regimens.

Former and current NFL athletes have been urging the league to allow its athletes to use cannabis to safely manage their aches and pains and perhaps even prevent brain damage caused by head trauma. The NFL Players Association has recently made an effort to amend the league’s rules regarding cannabis use by players. Dallas Cowboys’ owner Jerry Jones has voiced support for lifting the league’s marijuana ban.

It wasn’t until 2016 that the NFL publicly acknowledged a connection between football and CTE. The NFL has said in the past that it would listen to “science and medical experts” for its policies regarding cannabis, and that it would consider revisiting its stance if advised to do so. While cannabis remains prohibited, the NFL has voiced its support for additional study regarding cannabis use.

“The NFL is committed to supporting scientific research into CTE and advancing progress in the prevention and treatment of head injuries,” the NFL statement added. “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.”

In the study, McKee and her colleagues identified four states of pathological CTE severity among the brains, based on the buildup and distribution of tau. Stages one and two are classified as mild, while stages three and four are considered severe. The behavioral mood problems indicative of the disease are signs of a mild form, rather than severe. Memory loss and other cognitive symptoms were typically signs of a more severe stage.

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The researchers are now currently working to understand more about CTE and who is most susceptible. They’re examining how the lengths of exposure to head trauma, the age of first exposure, and the length of playing careers relates to the risk and severity of the disease.

“It certainly can be prevented and that’s why we really need to understand how much exposure to head trauma and what type of head trauma the body can sustain before it gets into this irreversible cascade of events,” McKee said.

McKee and her team are also using the 177 brains that were diagnosed with CTE to investigate the possibility of genetic risk factors.

“For the first time, we’ve established this really rich resource, not only of data, both the clinical symptoms and the pathological features, but also a tissue resource to enable future research in CTE,” McKee said. “And we know that this study doesn’t answer many of the very important questions in CTE, but the resource will help us understand the molecular underpinnings, will help us develop biomarkers and therapies by understanding the pathological features of the disease.”

Medical Marijuana, Inc. has supported CTE research and awareness in the past. We started the Show Your Green and Treat CTE campaigns in late 2015. Kannalife Sciences spokesman Marvin Washington is an 11-year NFL veteran who discussed the significance of CTE for NFL players and CBD as potentially beneficial on an episode of ESPN’s Outside the Lines.

You can access the entire study, “Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football,” via JAMA.

Learn more about cannabis’ therapeutic potential for CTE by visiting our education page.