Advances in CTE Research Bring Answers, but Also New Questions

Scans of the brain of former NFL football player Aaron Hernandez revealed a severe case of chronic traumatic encephalopathy, more commonly known as CTE. Photo courtesy of the BU CTE Center

Sarah Rappaport
BU News Service

In a study released last month, researchers from the Boston University Chronic Traumatic Encephalopathy (CTE) Center found that a protein called CCL11 could not only eventually aid in detecting CTE in live patients, but also help distinguish it from other neurodegenerative diseases, such as Alzheimer’s disease.

Currently, CTE can only be diagnosed by examining the brain after death.

Using three study groups — one that included the brains of 23 deceased football players with diagnosed CTE, one made up of 50 subjects with Alzheimer’s, and one with 18 non-athletes — researchers were able to verify a heightened presence of CCL11 in all 23 football players.

“The study is very preliminary,” BU CTE Center Clinical Research Assistant Bobby Abdolmohammadi said. “There were only 23 subjects, but this is the first step toward diagnosing the disease in life.

CTE is a neurodegenerative disease that is associated with repeated head injuries. Over a time period that can span decades, its symptoms — which include limited impulse control, memory loss, dementia, parkinsonism, depression and anxiety — will develop and worsen. In severe cases, patients may show tendencies toward suicide and aggression.

Though it will likely be years before an accurate diagnosis can be made in live patients, Abdolmohammadi said he hopes this discovery will lead to greater knowledge in terms of treatment plans.

“The end goal would be that you can develop therapeutic approaches based off of this information,” he said.

Challenges of Diagnosing CTE in Living Patients

Defining and understanding CTE is “the unicorn that everyone is chasing,” said Dr. Douglas F. Watt, a clinical and forensic neuropsychologist at Boston Neurological Services in Needham. What makes it particularly difficult is how little scientists know about neurodegenerative disease in general.

“We don’t understand any of these conditions, not even Alzheimer’s,” he said. “We’re still massively ignorant about what really is driving these biologically related processes.”

One of the most confusing aspects of CTE is its similarity to other neurodegenerative brain diseases. For instance, CTE mimics Alzheimer’s in its earlier stages, presenting with memory loss and lapses of judgment, though people with CTE appear to become symptomatic earlier in life.

According to Watt, one of the main differences has to do with “affective regulation” — that is, a person’s ability to regulate their emotional states. CTE tends to impact a person’s ability to do this more, though it is an issue in Alzheimer’s as well.  This can mean higher rates of depression and suicide.

Alzheimer’s patients also tend to be more susceptible to memory loss, while reduced impulse control and judgment seem to be common early symptoms of CTE.

Another thing that sets CTE apart from other diseases is a potential noticeable tendency towards suicide, according to BU’s Abdolmohammadi.

“[CTE] suicide cases typically present with behavioral mood conditions rather than cognitive conditions, as with older subjects,” he said.

Growing Concern About CTE

CTE is increasingly of concern in the world of athletics. A July study by the BU CTE Center concluded that out of the 202 deceased former football players examined, 177 of them were diagnosed for CTE, suggesting that CTE could be directly related to participation in football.

The disease was thrust into the spotlight again in September, when a postmortem examination of the brain of former New England Patriots tight end Aaron Hernandez showed a particularly severe form of CTE.

Based on an examination of his brain, BU CTE researchers concluded Hernandez had Stage 3 CTE, with Stage 4 being the most severe.

Hernandez was a star on the rise when he was drafted by the NFL in 2010. By 2015, he was facing life in prison without parole for the 2013 murder of Odin Lloyd.

On April 19, five days after being acquitted of a separate 2012 double homicide, Hernandez hanged himself in his prison cell. He was 27 years old.

“Hernandez… was so young,” said Abdolmohammadi, adding that he had likely reached Stage 3 CTE by the time he was 23, when he stopped playing football.

Regarding what could potentially determine vulnerability to CTE, Watt of Boston Neurological Services responded there is still much research to be done.

“Some football players seem to be doing fine,” Watt said. “Hernandez’s situation suggests that maybe some people should simply not be playing at all.

Legal Ramifications

Jose Baez, Hernandez’s defense attorney, has announced a $20 million lawsuit against the NFL and the New England Patriots on behalf of Hernandez’s former fiancée, Shayanna Jenkins-Hernandez, and their daughter.

Linda Kenney Baden, one of Hernandez’s former criminal defense attorneys, suggested the CTE findings could have explained instances of memory loss in previous cases.

She referenced former Kansas City Chiefs linebacker Jovan Belcher, who died in a murder-suicide in 2012 after killing his girlfriend. Belcher also showed signs of CTE.

“That would certainly explain his behavior,” she said.

CTE could eventually influence how athletes are charged in criminal court, said Baden. The disease would most likely be used to argue for sentence mitigation due to health, she said.

CTE could also create new legal challenges regarding brutal hits during games.

“The area of the law may be evolving, because we know how serious [CTE] is,” she said. “It could open up a whole area of the law for lawsuits by players and prosecutors who consider [these hits] an assault.”

Still, without a verifiable diagnosis in live athletes, Baden said this was still just speculation.

“Sure, it could be used as a defense, but whether a jury would allow something that isn’t observable is a different story,” she said.

Looking Forward

The BU CTE Center is continuing its research on both the analysis of deceased brains and the new findings concerning CCL11.

The center is beginning to receive more inquiries from families who want to donate the brains of loved ones, Abdolmohammadi said.

“We used to get four or five brains a year,” he said. “Now, we have received about one brain every other day since July and exponentially more calls.”

The center accepts brains from Olympic athletes and those who have played a professional contact sport at least two years at the college level. They also examine brains of people who have been victims of domestic abuse and second-impact syndrome, where a second concussion occurs before the first has properly healed.

Although there is still much to be learned, Abdolmohammadi said he is hopeful.

“I don’t think it is unreasonable to say that, at some point, we can find ways to diagnose CTE in live humans.”


Clarification: This article has been edited to reflect a change requested by Dr. Douglas Watt.  He initially stated that one of the main differences between Alzheimer’s and CTE is the patient’s cognition or awareness of their condition, but asked to amend that statement after publication. 

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