Do repeated impacts to the head and concussions cause CTE? The obvious answer is No. Does smoking cause lung cancer? Does drinking cause alcoholism? Does sugar intake cause type 2 diabetes? No, but they all have something in common. They increase your risk.

Overwhelming evidence does conclude that repetitive impacts to the head and concussions not only increase the risk but are a catalyst for the development of CTE. However, this should be a watershed moment. Given all the evidence and research, the questions we should be asking are, why do some people develop CTE and others don’t? And, how can we prevent it?

An article published in the Globe and Mail September 14, 2018 by Alan Maki “Zarley Zalapski’s story shows that CTE isn’t black and white”.

It discussed research conducted by Dr. Hazrati from the Hospital for Sick Children in Toronto who found CTE in a brain of a man that had never suffered a brain injury or played contact sports.[1]

The same article described another case where Dr. Hazrati did not find CTE in the brain of John Forzani. John was a former Calgary Stampeder’s offensive lineman who played seven seasons in the CFL and suffered many sub concussive impacts and more than one concussion.[1]

This one case alone serves to confirm that concussions do not always cause CTE. So, the compelling question is, why? If we could answer why John Forzani did not develop CTE it might help shed light on how CTE develops and, how it might be prevented.

First, head injuries can be caused by many other activities, at any age that may not result in any significant symptoms. It would be unusual and impossible to know whether someone had never taken a fall in the playground, fell off a swing, etc. at any time in their life.

According to the Government of Canada study [2], physical education class is ranked number two behind ice hockey and, many will be surprised to learn that the next contact sport is listed at number 8, North American Football. Tobogganing and playing tag are both ranked higher then football.

In order to understand how CTE develops, we first need to understand the spectrum of neurodegenerative diseases and the commonalities they all share. Alzheimer’s Disease (AD) is the most common form of dementia worldwide. Both CTE and AD are progressive degenerative disorders that cause the accumulation of a stabilizing protein called Tau.

Tau proteins are a necessary component in the structure of neurons, however alterations in its structure and function play a large role in many neurodegenerative diseases. There are at least 30 other vascular dementias referred to as Tau-opathies.

Continue on to Part 2: Tau, the Good, the Bad, and the Misunderstood.

References

[1] “Zarley Zalapski’s story shows CTE isn’t black and white” . The Globe and Mail.
[2] “Sport and Recreation-related Concussions and Other Traumatic Brain Injuries Among Canada’s Children and Youth”. Public Health Agency of Canada, Government of Canada.