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Chronic Traumatic Encephalopathy

Chronic Traumatic Encephalopathy (CTE) has classically been referred to as dementia pugilistica and is what many in the boxing world have long called “punch drunk” syndrome. CTE occurs when an individual experiences multiple concussions or traumatic head injuries. CTE is a disorder of chronic brain damage which persists over many years.

However, CTE isn’t restricted just to boxers, and surprisingly, given the fact that this long known condition emerged from observations in boxers, it is other field of sport that are recognising the importance neuropsychology in understanding the cognitive effects of CTE.

CTE overview

CTE is a degenerative illness that typically begins between 8 and 10 years after a mild traumatic brain injury or period of multiple concussive and sub-concussive blows to the head (McKee et al., 2009). Symptoms can include changes in mental health, personality and cognitive functions (thinking skills). Physical symptoms can include dizziness and headache. The brain deteriorates over time, resulting in a dementia-type set of symptoms.

Who develops CTE?

The key feature of CTE is the present of single or multiple concussive blows or head trauma. Because of this, the group of individuals that CTE is most common in, are athletes competing in contact sports (Saulle & Greenwald, 2012). Confirmed cases of CTE have been found in American football, ice hockey, boxing, rugby, football (with CTE linked to “heading” the ball” and wrestling (Stone, 2014; Daneshvar, Nowinski, McKee & Cantu, 2011).

Other groups where CTE diagnoses have been made include armed forces and military personnel, domestic abuse survivors and those participating in activities with repetitive head collisions (Daneshvaret al., 2011)


When initially first diagnosed in an NFL professional football player in 2002, CTE was only diagnosable through post-mortem examination. Recent efforts have been made to begin to research methods of diagnosis in living individuals, by identifying and measuring concentration of tau protein in the brain.

The hope of scientists is that with ways of identifying individuals with early onset CTE, we will be able to safeguard those who are at high risk in order to minimise the devastating effects of this condition. The researchers responsible for this on-going research are independent of any sporting organisation or body and fund their work through public donation, you can show your support HERE.

The neurology of CTE

In CTE we see changes in the including loss of mass in some areas and an increase in mass in others, becoming uncharacteristically large. CTE also involves the build-up in the brain of tau protein. Tau protein is made by the body to stabilise the cells (neurons) in the brain. But in CTE they become defective and cause abnormal changes in the cells. The three slides below are thin slices of brain. The brain on the left is a normal healthy brain. The slide in the middle was taken from a 73 year old world champion boxer. The slide on the right is from the brain of John Grimsley (1962-2008) American Footballer who played for seven seasons with the Houston Oilers. 


Figure 1 - Cells in slices of human brains from a healthy sample (left) to CTE in athlete brains (centre and right)

The brain specimens of the boxer and American footballer, show thick dark brown patches taking over the cells of the brain, these are tau proteins, and are responsible for degeneration of the brain in CTE.

Since the discovery of CTE in American football legend Mike Webster, whose experience of CTE was immortalised in the recent Hollywood movie “Concussion”, many other cases are being unearthed within the sport and our knowledge of the disease is expanding. Work from Neurophysiologist Dr Ann McKee has identified four stages of the disease:

Figure 2 - The four stages of CTE  development

So what we know is that CTE is a degenerative disease affecting the brains of those who sustain frequent head trauma and concussion. Importantly, recent evidence has also suggested that a build of head blows which do not necessarily cause a concussion (sub-concussive blows) can have a similar such effect.

Figure 3 - A healthy brain compared to a brain with advanced CTE

With thanks to the Boston University Center for the Study of Traumatic Encephalopathy for images and their on-going research in this area.

CTE Symptoms

CTE can have profound and life-changing effects on individuals. Symptoms include:

Cognitive (thinking) skills: Impaired memory, impaired impulse control
Mental Health: Erratic behaviour, aggression and violent behaviour, depression and suicidality
Social: Relationship breakdown
Physical: Gradual onset of dementia, poor balance

It is likely that it is common that individuals with CTE either attribute the changes that they see either to ageing or they may indeed be mis-diagnosed with similar conditions including Parkinson’s disease or Alzheimer’s disease.