• Posted October 28, 2025

CTE Not Likely Among People With Few Concussions, Experts Report

Folks who’ve suffered one or two concussions at some point shouldn’t worry about developing chronic traumatic encephalopathy (CTE), a new study has concluded.

CTE is more common in people who experience many repeated head impacts, like the football players in whom the disorder was first identified, researchers recently reported in the Journal of Neuropathology & Experimental Neurology.

In all, 7 out of 47 donated brains had CTE as confirmed by autopsy — and six of those donors had lifetime histories of extensive repetitive head impacts, researchers found.

The seventh person had suffered two severe concussions in their medical history, but no known repetitive head impacts, researchers said.

“Our study underscores that CTE is rare among individuals with lower amounts of repetitive head impact and in those with isolated traumatic brain injuries, and highlights why community-based research — beyond brain donation from select populations such as professional athletes — is crucial,” senior researcher Kristen Dams-O’Connor said in a news release. She’s director of the Brain Injury Research Center at Mount Sinai in New York City.

People with CTE suffer from memory loss, problems with attention and concentration, violent mood swings, impulsive or erratic behavior and poor muscle concentration, according to Harvard Medical School.

For the study, researchers analyzed brain tissue from 47 people donated between 2018 and 2024. The team also used medical records, autopsy reports and family interviews to figure out each person’s exposure to head injuries.

Among the seven people with CTE, all were men and four had participated in contact sports, results showed. Three were college football players and one was a boxer.

Another person with CTE had suffered head injuries both as a military veteran with combat experience and during an abusive relationship, researchers wrote. The sixth person received repeated head injuries during 18 years of child abuse, as well as from car accidents, falls, and drug and alcohol blackouts.

The seventh, more inexplicable case involved a person who’d sustained two moderate-to-severe concussions 30 years and 3 years prior to their death, researchers said.

The other 40 participants had various levels of some repetitive head trauma. Four non-CTI participants were college football players and a few had one or more isolated traumatic brain injuries in their records. 

Researchers concluded that CTE risk is likely highest among people with extensive repetitive head impacts, which they defined as five or more years in which a person suffers repeat concussions.

“While the findings continue to suggest that CTE can be linked to extensive, repeated head impacts, they also underscore the need to better understand how distinct types of head trauma relate to CTE risk, as well as the need to identify additional risk and protective factors,” lead researcher Enna Selmanovic, a doctoral student at Icahn School of Medicine at Mount Sinai, said in a news release.

However, the researchers said more work is needed studying brains that have been subjected to different levels of concussion and injury, to better understand why CTE occurs in some but not others.

“Continued work in diverse populations is essential to move the conversation beyond assumption and towards evidence,” Selmanovic said.

More information

Harvard Medical School has more on CTE.

SOURCES: Mount Sinai, news release, Oct. 23, 2025; Journal of Neuropathology & Experimental Neurology, Oct. 18, 2025