Boston University researchers say they have now diagnosed 345 former NFL players with chronic traumatic encephalopathy (CTE) out of 376 former players studied.

In comparison to that 91.7% CTE rate of studied former NFL players, a past BU study of 164 brains of men and women found that only 1 of 164 (0.6%) had CTE. The lone CTE case was a former college football player.

The BU researchers noted that they’re not saying 91.7% of all current and former NFL players have CTE because brain bank samples are subject to selection biases. The prevalence of CTE among NFL players is unknown, as CTE can only be diagnosed after death.

Repetitive head impacts appear to be the chief risk factor for CTE — which is characterized by misfolded tau protein that is unlike changes observed from aging, Alzheimer’s disease, or any other brain disease.

“While the most tragic outcomes in individuals with CTE grab headlines, we want to remind people at risk for CTE that those experiences are in the minority,” said Ann McKee, director of the BU CTE Center and chief of neuropathology at VA Boston Healthcare System.

“Your symptoms, whether or not they are related to CTE, likely can be treated, and you should seek medical care,” McKee added. “Our clinical team has had success treating former football players with mid-life mental health and other symptoms.”

Research on CTE has advanced considerably over the past five years, and the BU CTE Center will soon publish its 182nd study on CTE.

In part because of advances in CTE research, the National Institutes of Neurological Disorders and Stroke recently updated their position on what causes CTE: “CTE is a delayed neurodegenerative disorder that was initially identified in postmortem brains and, research-to-date suggests, is caused in part by repeated traumatic brain injuries.”

“We’d like to thank our 1,330 donor families for teaching us what we now know about CTE, and our team and collaborators around the world working to advance diagnostics and treatments for CTE,” McKee said.

McKee and her team are inviting former athletes, including women, to participate in research studies designed to learn how to diagnose and treat CTE.

The BU CTE Center is collaborating with its education and advocacy partner the Concussion Legacy Foundation to recruit former football players and other contact sport athletes to five active clinical studies.

One of the studies, Project S.A.V.E., is recruiting men and women ages 50 or older who played 5-plus years of a contact sport, including football, ice hockey, soccer, lacrosse, boxing, full contact martial arts, rugby and wrestling.

To learn more about Project S.A.V.E. and four other studies enrolling participants, visit www.bu.edu/cte/our-research/clinical-research/.