Study: Hits to head may cause CTE even without concussions

New research out of Boston University's CTE Center suggests that smaller blows to one's head—hits that fail to register any symptoms of a concussion—can also or may be the cause of the neurodegenerative disease CTE.

These researchers studied the brains of four teenage athletes who suffered brain injuries at varying points in time before their deaths and the damaged brains of mice. The researchers hypothesized that damaged blood vessels leaking into brain tissue may cause early CTE.

Dr. Derek Chong, the vice chair of Lenox Hill Hospital's Neurology Department, said researchers are getting closer to really understanding CTE but are not very close to being able to do something about it. Chong said that even if sub-concussive hits may cause CTE, how hard of a hit a brain can withstand without risking CTE still remains a mystery—and likely varies from brain to brain.

In the study's final stage, researchers used computer models to find evidence that what causes a concussion may differ from what causes CTE.

"We may need to re-define what a concussion is or come up with another name for it to keep people safe," Chong said.

The researchers hypothesized their new findings might at least partially explain why 20 percent of those diagnosed with CTE has never suffered a diagnosed concussion.