Ken Stabler and Other Victims: What Is CTE and Who Gets It?

Chronic traumatic encephalopathy is a progressive, degenerative brain disease found in athletes and others who have been hit repeatedly in the head, according to the Boston University CTE Center.

It has been known since the 1920s that it affects boxers but in recent years researchers have turned their attention to other athletes, professional football players in particular, though CTE has also been found in soccer, rugby and baseball players.

The connection between football and CTE was first discovered by Dr. Bennet Omalu, a forensic neuropathologist who performed an autopsy on Mike Webster, the center for the Pittsburgh Steelers. The 2015 movie “Concussion” documented the discovery of the link, which the NFL did not acknowledge until March 2016.

The brain tissue of 90 of 94 former NFL players who were studied had CTE, according to a lab of the VA Boston Healthcare System and the Boston University CTE Center but so far researchers have be able to test for the disease only through autopsies. In September, two separate teams of researchers announced that they had made progress toward diagnosing people who are alive, either by identifying the disease’s biomarkers or by locating an abnormal protein distinctive of the disease, tau, in the blood. Researchers believe CTE is related to a buildup of tau, which is also a hallmark of Alzheimer’s disease, according to the Alzheimer’s Association.

Changes in the brain may not begin for decades.

CTE is associated with memory loss, confusion, impaired judgment, problems with impulse control, aggression, depression, and, eventually, progressive dementia.

But though researchers believe CTE is caused by repetitive brain trauma, the number of hits and the types that will trigger it are not known. It is likely that genetics may play a role but how is not understood, according to Boston University.