BU Center Finds Brain Disease in NHL Enforcer

BU researchers have discovered the degenerative brain disease chronic traumatic encephalopathy (CTE) in a recently deceased former National Hockey League player known for his aggressive play, including hundreds of on-ice bare-knuckle brawls.

Bob Probert, who played left wing for 16 seasons in the NHL, including for the Detroit Red Wings and Chicago Blackhawks, died of a heart attack last year at age 45. Although Probert scored 163 goals, had 221 assists, and was named to the 1987-88 NHL All-Star team, he was best known as an enforcer, racking up 3,300 penalty minutes (fifth highest in the NHL) and brawling in more than 200 fights. Probert is the second former NHL player diagnosed with CTE; the first was Reggie Fleming, who died in 2009 at the age of 73 with dementia, following 30 years of worsening behavioral and cognitive difficulties. CTE can be diagnosed only by examining brain tissue postmortem.

BU’s Center for the Study of Traumatic Encephalopathy (CSTE) has analyzed the brains of 40 former athletes. More than 30 have shown signs of CTE, including 13 of 14 former NFL players, as well as college and high school football players, hockey players, professional wrestlers, and boxers. The CSTE brain bank contains 68 donations, including most recently the brain of former NFL Chicago Bears star safety Dave Duerson, who committed suicide two weeks ago and left instructions for his family that his brain be donated to the center for study.

CSTE codirector Christopher Nowinski says despite notable rule changes in high-profile athletic territory like the National Football League, when it comes to on-the-field head blows and brain trauma, the surface is just being scratched.

“Early evidence indicates that the historical decision not to discourage contact to the head was an enormous mistake,” says Nowinski, a former professional wrestler who retired with post-concussion syndrome, “and we hope aggressive changes continue to be made to protect athletes, especially at the youth level.”

CTE was originally referred to as “dementia pugilistica” because it was thought to affect only boxers. Researchers believe that the progressive brain disease is caused by repetitive trauma to the brain, including concussions or subconcussive blows. However, they add, it’s likely that other not-yet-discovered factors, such as genetic predisposition, are at play and put certain individuals at greater risk of developing this neurodegenerative disease.

CTE is characterized by deposits of an abnormal protein called tau, in the form of neurofibrillary tangles, glial tangles, and neuropil threads throughout the brain, and in some cases, the presence of another protein—associated with motor neuron disease—known as TDP-43. These abnormal proteins are associated with the impaired functioning and eventual death of brain cells. CTE sufferers may display symptoms such as memory impairment, emotional instability, erratic behavior, depression, and problems with impulse control. Eventually, the condition may progress to full-blown dementia. Although similar to Alzheimer’s disease, CTE is pathologically distinct and is the only known preventable cause of dementia.

Probert’s wife of 17 years, Dani Probert, says, “Bob told me he wanted to donate his brain to Boston University after learning about the research on 60 Minutes. His sole motivation was to make sports safer for our children. Bob was a great husband and father, and we miss him every day.”

Born and raised in Ontario, Canada, Probert long struggled with substance abuse, including alcohol and cocaine, and entered rehab several times during his career. Dani Probert notes, however, that her husband exhibited a mental decline in his 40s, displaying new and growing problems with short-term memory, attention, and a short fuse, which are all symptoms consistent with the clinical picture of CTE displayed by other athletes. During discussions in the last year of his life, Dani Probert says, her husband believed he had had three or four significant concussions, although when he counted what he considered “getting his bell rung,” which by definition is concussion, he suffered over a dozen. The NHL recently banned blindside hits to the head in an effort to reduce brain trauma, but fighting has always been, and remains, part and parcel of the sport for players and fans.

“The diagnosis of CTE in Probert’s brain is not necessarily an indictment of hockey, as he received brain trauma during hockey fights as well as outside of sports, including a major car accident,” Nowinski says. “Reggie Fleming, the only other NHL player diagnosed with CTE, also was an enforcer, so we need further study before this research can truly inform that ongoing, and important, debate.”

Retired NHL star Keith Primeau hopes this research will continue to have an impact on policy to protect the brains of current and future hockey players. He is one of more than 300 athletes participating in a longitudinal study of brain trauma at CSTE that will culminate in brain and spinal cord donation.

“Hockey continues to make positive steps to protect players from concussion and brain trauma,” Primeau says, “and I hope the findings from the study of my friend Bob Probert will accelerate that momentum throughout all levels of the game.”

Read more coverage of the links between head trauma and dementia here.