So far, chronic traumatic encephalopathy
(CTE) has been observed only in the
brains of people with a history of brain injury or multiple concussions.
Now, researchers at Toronto Western Hospital's Canadian Concussion Center
(CCC) have discovered the presence of chronic traumatic encephalopathy
in the brain of a deceased patient with no known history of
traumatic brain injury or concussion, the first known case of its kind.
‘Chronic traumatic encephalopathy (CTE) presence in an individual who had no known head trauma, or showed no signs of dementia, highlights that the cause of CTE might be more complex than previously assumed.’
The case study, published in the International Journal of Pathology and Research
and presented at the CCC's 5th annual symposium on Research on the
Concussion Spectrum of Disorders, discusses the unexpected finding which
resulted from an autopsy examining the brain of a patient with a
seven-year history of clinically diagnosed amyotrophic lateral sclerosis
(ALS) and motor neuron disease (MND), yet no history of head trauma or
any participation in activities associated with risk of concussion,
according to his family.
"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," says Dr. Lili-Naz
Hazrati, neuropathologist with the CCC research team who conducted the
"We are not questioning that a relationship may exist between
repetitive head trauma and brain degeneration," she continues. "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."
"Finding CTE in a patient without a history of concussion is an
interesting development that opens up our understanding of this
disease," says Dr. Charles Tator, Director of the CCC and a co-author of
the case study. "As researchers, we need to go where the evidence takes
us, and it now seems possible that CTE affects a wider range of people.
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."
To date, 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.
The majority of brains studied by the CCC and other centers have
come from donations made as a result of concern over symptoms - usually
of unexplained cognitive impairment - displayed while the individual
was alive, though not all of these cases resulted in findings of the CTE
tauopathy in the brain. However, the referral of brains of symptomatic
individuals who have a history of concussions increases the chances
that some form of brain degeneration - whether CTE or other - would be
present, which has potential to create a sample that isn't
representative of the overall population.
"Obviously brain trauma and repetitive brain trauma can result in
cognitive impairment and possibly contribute to a neurodegenerative
disease," says Dr. 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 labeling trauma as the only possible cause of
CTE because it looks to be more complicated than that."