"Objective" results from the use of diffusion tensor MR imaging has clearly shown that over 40 percent of retired National Football League (NFL) players show signs of traumatic brain injury, according to a large-scale study set for release at the American Academy of Neurology’s 68th Annual Meeting starting April 15 in Vancouver, Canada.

“This is one of the largest studies to date in living retired NFL players and one of the first to demonstrate significant objective evidence for traumatic brain injury in these former players,” Dr. Francis X. Conidi, the study's author said in a statement. “The rate of traumatic brain injury was significantly higher in the players than that found in the general population.”

These recent findings fly in the face of years of denial by the NFL, which cited concussion research that the New York Times described as "flawed" in March. That research involved keeping a database from 1996 to 2001 in which all team doctors recorded details of diagnosed concussions in players, who were kept anonymous.

When the paper obtained the data it, "was able to determine the identities of all of the teams and many of the players. Subsequent analysis confirmed that at least 100 concussions, including some serious ones to the game’s top players, were not included in the league’s studies," according to the paper.

Dr. Joseph Waeckerle, who was on the concussion committee, reported to the Times that he had not known about the missing cases. “If somebody made a human error or somebody assumed the data was absolutely correct and didn’t question it, well, we screwed up. If we found it wasn’t accurate and still used it, that’s not a screw-up, that’s a lie.”

This latest study just released at the AAN meeting looked at scans of 40 retired players, ranging in age from 27 to 56 years, who had suffered an average of just over 8 concussions each. "On the tests of thinking skills, about 50 percent had significant problems on executive function, 45 percent on learning or memory, 42 percent on attention and concentration, and 24 percent on spatial and perceptual function," the study reported.

“We found that longer careers placed the athletes at a higher risk of TBI,” said Conidi. “This research in living players sheds light on the possible pathological changes consistent with chronic traumatic encephalopathy that may be taking place.”

The issue of concussions and football has been coming to a head for some time. In late 2015 an editorial in The AAN's journal "Neurology" noted a "societal conversation about the risks of contact sports" had been instigated by the alarming incidence of concussion-related brain trauma in such activities.

On March 13, 2015, Chris Borland, a star rookie linebacker on the San Francisco 49ers, announced his early retirement from professional football, citing concerns about chronic traumatic encephalopathy (CTE). Borland, who had a history of 2 diagnosed concussions, walked away from a multimillion-dollar contract and potential sports superstardom, explaining that, "from what I've researched and what I've experienced, I don't think it's worth the risk."

Perhaps just as surprising as Borland's announcement was the support he received from teammates and other athletes – support that reflects a growing recognition in the athletic community that repetitive head trauma may be associated with CTE and other forms of dementia," Dr. Brian Edlow and Dr. Holly Hinson stated in their editorial in the journal last October.

In August, 2013, the NFL settled, for $765 million, a lawsuit brought by 4,500 players and families over charges the league had hidden its knowledge of the impact of repeated blows to the heads of athletes.

“The settlement seems low considering the number of claimants and the severity of their conditions, but it also shows the uphill climb in proving the league was responsible for the players’ injuries,” University of Illinois law teacher Michael LeRoy told the New York Times. “The league is keenly sensitive to its public image. It changes the conversation and really lets the air out of the publicity balloon.”

This latest study, however, may re-inflate that balloon — and reignite debate about whether football's athletes can ever be adequately protected from traumatic brain injury.