They administered a few mild blows to the heads of the lab mice: the force was equivalent to the impact of a right hook to a human, or a helmet-to-helmet football collision, but the blows did not always cause concussions in the mice, says Goldstein.
This study provides the "best evidence we have so far", he added, that it's really those subconcussive impacts (those below the threshold of an actually concussion) that are unsafe and cause CTE. "We have been in close touch with the researchers at Boston University, who are also members of our Mackey-White Health and Safety committee, and we will review this study carefully to consider future changes to improve the health and safety of our players".
Efforts to protect athletes have largely focused on preventing concussions, but the study suggests that head injuries that are not strong enough to cause a concussion can lead to CTE.
Although the study was small, Goldstein said studying even single cases of CTE can help researchers develop hypothesis to test.
"On the football field, we're paying attention to the bright, shiny object - concussion - because it's obvious", said Dr. "And now that scientists know exactly what's happening that opens the door for people to try to find inventions to try to stop what's happening".
The new findings shocked researchers, but they mirror what athletes see on a regular basis, said Chris Nowinski, a former pro wrestler and CEO of Boston-based Concussion Legacy Foundation.
Boston University's CTE Center recently found that 110 of the 111 formal National Football League players are diagnosed with CTE.
But with these new findings, lead author Dr.
Tau protein is one of the signature markers in brains affected by CTE.
One brain was found to have early-stage CTE, and two others showed abnormal accumulation of the tau protein associated with the disease.
It's "an important study that presents a new hypothesis which, if true, would have implications for public health", said Steven Atlas, MD, MPH, a primary care physician and associate professor of medicine at Harvard Medical School who is a contributor to HealthNewsReview.org. The researchers hypothesized that damaged blood vessels leaking into brain tissue may cause early CTE. "The symptoms start early and progress even without subsequent hits".
In fact, it was mice studied in a laboratory who provide the primary basis for the headline claims in the news release and subsequent stories.