Frequently Asked Questions about CTE

What is CTE?

Chronic Traumatic Encephalopathy (CTE) is a progressive degenerative disease of the brain found in people with a history of repetitive head impacts (RHI) often incurred during contact sport play, military service, and other activities that involve repeated blows to the head. These may include symptomatic concussions as well as subconcussive hits that do not cause symptoms. Subconcussive hits are routine in many sports, including checking in ice hockey and heading the ball in soccer. CTE has been known to affect boxers since the 1920’s (when it was initially termed punch drunk syndrome or dementia pugilistica).

In recent years, reports have been published of neuropathologically confirmed CTE found in other athletes, including football and hockey players (playing and retired), as well as in military veterans who have a history of repetitive brain trauma. CTE is not limited to current professional athletes; it has also been found in athletes who did not play sports after high school or college.

The repeated brain trauma triggers progressive degeneration of the brain tissue, including the build-up of an abnormal protein called tau in a unique pattern. The pattern of tau seen in the brains of those with CTE is distinct from other neurodegenerative diseases such as Alzheimer’s disease (AD), progressive supra nuclear palsy (PSP), and corticobasal degeneration (CBD). These changes in the brain can begin months, years, or even decades after the last brain trauma or end of active athletic involvement. The brain degeneration is associated with common symptoms of CTE including memory loss, confusion, impaired judgment, impulse control problems, aggression, depression, suicidality, parkinsonism, and eventually progressive dementia.

In both sets of photographs below, the brain tissue has been immunostained for tau protein, which appears as a dark brown color.

Tau immunostained sections of medial temporal lobe from 3 individuals:

Whole brain section from a 65 year old control subject showing no tau protein deposition.

Whole brain section from a 73 year old world champion boxer with severe dementia showing very severe tau protein deposition in the amygdala and thalamus.

Whole brain section from John Grimsley showing abundant tau protein deposition in the amygdala and adjacent temporal cortex.

Microscopic section from 65 year old control subject showing no tau protein deposition.

Microscopic section from John Grimsley showing numerous tau positive neurofibrillary tangles and neurites in the amygdala.

Microscopic section from a 73 year old world champion boxer with severe dementia showing very severe tau protein deposition in the amygdala and thalamus.