Chronic traumatic encephalopathy (CTE) is classified as progressive brain degeneration apparently caused by repeated head trauma or multiple occasions of concussion. An increasingly studied pathology, CTE is common in athletes who experience cranial damage, e.g. players of American football, rugby, ice hockey, wrestling, mixed martial arts, and soccer. The world’s most popular sport, soccer is frequently played by about 250 million people in over 200 countries. Especially in headers of the beautiful game, CTE is a prominent threat, one that can only be properly diagnosed after death.

Chronic Traumatic Encephalopathy

CTE was first classified in reference to boxers, calling those experiencing a state of progressive cognitive impairment that developed over a career of repeated head trauma “punch drunk.” “Fistfighter’s dementia,” “boxer’s madness,” and dementia pugilistica all followed in the line of nomenclature, though these terms were retired as awareness increased that the condition is not reserved for boxers alone. Nearly all athletic subjects examined have sustained some cognitive deficits, though a small minority are asymptomatic at time of death. 

CTE research has illustrated that the condition affects all players differently, resulting in usually one of two forms of cerebral impairment: cognitive and behavioral. The initial features of the behavior (or mood) variant are consistently seen in players’ younger years, resulting in mood disturbances and behavior changes. For the rest of the players examined, cognitive impairment was observed later in life. This variant includes memory loss, executive dysfunction, gait impairment, and slurred speech.

CTE in Soccer Players

A study in the UK conducted from 1980 to 2010 observed 14 retired soccer players with signs of CTE. Over the 30-year span, players’ conditions were regularly observed until their deaths when, with familial permission, post-mortem autopsies were conducted. The research concluded that these retired soccer players sustained cognitive and structural changes to their brains related to their past prolonged exposure to repetitive concussive or subconcussive head impacts from heading and head-to-player collisions.

Parameters

On average, a professional soccer player heads the ball 6-12 times during each game. Over a 20-year career, players can perform at least 2,000 headers during professional  games, to say nothing of the number performed during practice. While head injuries can be sustained during the head-to-ball contact of heading the ball, significantly more soccer-related head injuries occur during head-to-head impact, when one player’s head collides with another’s.

Of those players studied for this research, all had played soccer for an average of 26 years. Each player was a skilled header, though only six had a history of concussion, one each. 

At Risk of CTE

All of the players examined developed progressive cognitive weakness, specifically those signs associated Alzhiemer’s pathology (dilatation of the third ventricle, tau pathologies, and septal irregularities). Cerebral signs of damage arose on average at the age of 63.6 years, and symptoms continued for an average of 10 years before death. 12 of the 14 players examined died from advanced neurodegenerative disease.

Though concussions receive a lot of press and can cause severe trauma to the brain, they are not a prerequisite for CTE. Many blows to the head do not result in concussion and evident neurological symptoms. However, if subtle neuropsychiatric deficits follow a head injury that does not yield concussion, it is referred to as subconcussion. Though only six of the 14 soccer players had history of concussion, all of the players developed CTE pathologies.

For all six cases with concussion history, neuropathological investigation revealed septal irregularities, indicative of a history of repetitive head collisions. 67% of these cases had pathologically confirmed CTE with conditions that included Alzheimer’s disease, hippocampal sclerosis, dementia, and others.

Protecting Players

The study funded by The Drake Foundation in the UK discovered that retired soccer players with a past history of repetitive head impacts have an increased risk of chronic traumatic encephalopathy (CTE), resulting in dementia and motor impairments. As soccer is so well-loved across the world, this correlation should be of considerable public health interest.

The pervasive nature of CTE among athletes in general and soccer players in particular warrants further systematic investigation. While symptoms are pervasive in these athletes, large-scale studies are needed to more precisely identify at-risk groups and causitory behaviors. The further information this will bring will justify the implementation of protective strategies.

As currently diagnosis of CTE can only be confirmed by neuropathological examination, there is an opportunity to better diagnose and treat the underlying pathology of CTE, in soccer players and otherwise. Diagnostic methods of ascertaining levels of the TDP-43 protein, which is brain protein found in patients with dementia, and monitoring the progress of its pathology must be improved if we are to better identify and treat CTE cases.