TORONTO - Researchers at Toronto Western Hospital's Canadian Concussion Centre have discovered the presence of chronic traumatic encephalopathy in the brain of a deceased patient with no known history of concussions.
They say it's the first known case of its kind.
The case study was published in the International Journal of Pathology and Research and presented at the centre's annual symposium on concussion research.
The finding resulted from an autopsy examining the brain of a patient with a seven-year history of amyotrophic lateral sclerosis, known as ALS, and motor neuron disease.
The patient's family said he had no history of head trauma or any participation in activities associated with risk of concussion.
Chronic traumatic encephalopathy, or CTE, is a neurodegenerative brain disorder that has been linked to multiple concussions.
"The finding of CTE in an individual who not only had no known head trauma, but also showed no signs of dementia or cognitive impairment and was high functioning mentally until his death, highlights that the cause of CTE might be more complex than we assume," Dr. Lili-Naz Hazrati, a neuropathologist with the research team who conducted the autopsy, said in a release.
Previously, researchers have only seen CTE in the brains of people with a history of brain injury or multiple concussions, Hazrati said.
"We are not questioning that a relationship may exist between repetitive head trauma and brain degeneration," she said. "But, at this point in time, we have more questions than answers about the definitive causes of CTE, and findings like these give us new directions to pursue and investigate."
Dr. Charles Tator, director of the concussion centre and co-author of the study, said it was an "interesting development" that would help provide more understanding of the disease.
"As researchers, we need to go where the evidence takes us, and it now seems possible that CTE affects a wider range of people," he said.
"The more we know about this disease, the more likely we'll be able to figure out how to treat it and perhaps eventually prevent it."
According to the concussion centre, brain autopsies of cases where individuals reported suffering multiple concussions have yielded a wide range of results, including no neuropathological changes in the brain, presence of CTE alone, presence of CTE and another neurodegenerative disease, or a non-CTE neurodegenerative disease only.
"Obviously brain trauma and repetitive brain trauma can result in cognitive impairment and possibly contribute to a neurodegenerative disease," said Hazrati.
"But since we've seen cases of brains that experienced multiple concussions but don't have CTE, and now a brain with CTE but absence of any head trauma, there is indication that we should be cautious about labelling trauma as the only possible cause of CTE because it looks to be more complicated than that."
CTE has been found in the brains of multiple former athletes. The National Football League and National Hockey League were sued by former players who suffered concussions and other head injuries. The NFL settled for US$1 billion, while the suit against the NHL is pending. The CFL has also been named in a class-action lawsuit over concussions and brain trauma.