Football players brain disease CTE appears rare in military

A new study suggests that a brain disease caused by repeated blows to the head and concussions — most notably found in hundreds of former NFL players — is rare in service members.

Chronic traumatic encephalopathy, or CTE, has been linked with contact sports, especially football and boxing. More recently, the military experience, to include blast exposure, has been discussed as a potential risk factor for the disease.

But a study of 225 donated brains of deceased active duty and retired service members by researchers at the Uniformed Services University of the Health Sciences, set to be published Thursday in the New England Journal of Medicine, says CTE in service members is more strongly linked to civilian traumatic injuries.

“Our study suggests that CTE is rather rare in US service members and when seen, it tends to be rather mild in terms of brain involvement and is typically associated with prior participation in contact sports, especially football,” said Dr. Dan Perl, one of the study’s lead researchers and a professor of pathology.

Perl is director of the Department of Defense/Uniformed Services University Brain Tissue Repository, which is essentially a brain bank. The brains studied had been donated for use in research.

Scientists found that 10 of 225 brains, or 4.4%, had CTE. All 10 of those service members had a history of participation in contact sports.

In comparison, the researchers cited a Boston University study, published in the Journal of the American Medical Association in July 2017, which found the progressive, degenerative disease in 87% of the brains of 202 former US football players. CTE was found in 99 percent of the brains obtained from National Football League players, 91 percent of college football players and 21 percent of high school football players.

The brain disease can only be diagnosed after death with an examination of the brain. It is believed that those with CTE develop a range of cognitive, behavioral, mood and motor issues later in life.

Of the 45 brains of service members who had a history of blast exposure, three had CTE, compared with seven brains out of 180 from those who didn’t have a history of blast exposure.

But the researchers included important caveats.

“It should be kept in mind that most of the individuals studied in this report who had been heavily exposed to combat and especially to blast, died at a relatively young age,” Perl said. “Studies of CTE in contact sport athletes show that there is a considerable period of [time] between when they are exposed to head trauma during their athletic careers and when they become symptomatic with the disease. …

“In coming years, we may identify additional cases of CTE in former service members who served in the 20-year-period of the War on Terror (2001 to 2021) and who were so extensively exposed to blast.

“Only time and further studies will tell.”

Because of the small number of CTE cases, definitive conclusions can’t be made regarding the links between blast exposure and CTE, the researchers stated. But their findings suggest that the prevalence of CTE is rather low.

Another caveat is that gathering accurate traumatic brain injury information in military and civilian settings is a challenge; some aspects of the individuals’ histories were obtained retrospectively from next of kin.

CTE is identified by a distinct pattern of pathology in the brain. Scientists looked for characteristic lesions that are only seen in this disease, Perl said. The lesions aren’t the immediate result of any head injury, and have been mostly reported in people who had repeated head injuries such as former boxers or professional football players.

“The CTE lesions are thought to be later degenerative responses to the numerous blows to the head, not to any individual injury,” he said.

This study also indicates that CTE is not a significant contributor to psychiatric disorders, alcohol and substance abuse, and suicide in these service members. While four of the 10 brains came from service members who died of suicide, the majority of the suicide cases they examined in the study didn’t show evidence of CTE. The study included 49 brains from service members who died of suicide, and four of those had CTE.

“Accordingly, we could not conclude that CTE was an important contributor to this important problem,” Perl said. ”We feel that continuing study of biologic underpinning of military suicide is a very important part of our mission and we will be continuing to study it.”

• Researchers found that 10 of the 225 brains had CTE. All 10 of those had participated in contact sports. But there was an additional factor for eight of those: They’d had a non-sports-related traumatic brain injury in civilian life. Overall, the disease was present in eight of 44 brains from service members who had had non-sports-related TBI in civilian life.

• Of the 21 brains of those who had a head injury during military service caused by the head striking a physical object without blast exposure, three had CTE.
• Of the 60 brains of service members who had participated in contact sports, 10 had CTE, compared with none of the 165 who had not participated in contact sports.