A new study of former NFL players' brains found CTE in nearly 25%. What do experts say concerned current players should do about that?

A new study on the degeneration of NFL players' brains sent "a sobering reminder that football carries real risks," the NFL Players Association said Tuesday.

A study published in the British Medical Journal reported that at least 24.5% of former players' brains studied showed signs of chronic traumatic encephalopathy (CTE), a degenerative condition diagnosed from X-rays showing abnormal protein clumps. As of now, the condition has been diagnosed only after death. The study analyzed the brains of former players who died between 2016 and 2021. 

The union told its players in an email blast that the findings "should serve as a call to action across the entire football ecosystem." The NFL issued a statement that similarly preached proactive healthcare.

"The NFL remains committed to ensuring that the NFL community has access to a robust — and expanding — set of resources to enhance their physical and mental wellbeing," an NFL spokesperson said in a statement obtained by Yahoo Sports, in part. "We encourage former players to utilize these resources to identify and seek treatment when they are concerned about their health."

Identifying and seeking treatment during a former player's lifetime, some experts say, is an important step that research on postmortem diagnoses can overlook.

Dr. Rachel Grashow, the senior director of research initiatives for the Football Player Health Study at Harvard University, said the study's linkage between brain injury and CTE helps quantify the pathology, or study of the disease; but the scientific community and public definitions of CTE often don't align, Grashow said. People diagnosed with CTE have shown symptoms including cognitive impairment, behavioral changes, mood changes and movement troubles, Mayo Clinic says. But the postmortem diagnoses have complicated the ability to discern correlation from causation.

"As of yet, they haven't been able to tie symptoms," Grashow told Yahoo Sports by phone Tuesday night. "You can't connect symptoms to pathology yet."

What researchers believe they can do, and the NFL and NFLPA are emphasizing, is treat symptoms of repetitive brain injury during players' lives. The league, union and medical experts wonder whether healthcare adjustments during the years between a player's retirement and their death — a period often studied less than CTE research after their death — could reduce the severity of impact.

"Head injury causes a lot of conditions that aren't good for you," Grashow said. "But if you treat those conditions, that's possibly the best thing you can do for your brain, since you can't go in a time machine and undo how much head injury you had."

The NFL has tweaked rules in recent decades in hopes of reducing the frequency and severity of concussions and associated traumatic brain injuries.

Helmet regulations have advanced, including the increasing popularity of the league's Guardian Cap. Concussion protocols have become stricter and more formalized. The most dangerous phase of the game for head injuries — the NFL kickoff, where high-speed collisions unfolded often — has been overhauled.

Still, the football ecosystem seems to tacitly acknowledge head injuries will not be eliminated from football anytime soon. Instead, the league, union and researchers wonder how to treat the conditions that result from this inherent risk.

NFLPA executive director JC Tretter and NFLPA medical director Dr. Thom Mayer met with the lead author of the study published Tuesday, a union source told Yahoo Sports. Dr. Daniel Daneshvar of Massachusetts General Brigham and Boston University advised in an email to players: "Many of the symptoms associated with CTE are treatable with the right care."

"While we don't have a cure yet, we have seen improvements in players who receive care from doctors specializing in neurodegenerative disease and who know how to treat athletes," Daneshvar said, per the union email."No one should walk away thinking there's nothing they can do."

The union will hold a call with medical experts in the coming weeks to answer player questions and create a forum for discussion, according to a copy of the union's email to players obtained by Yahoo Sports.

The league said it will continue to consider in-game safety strategies.

In the analysis of 5,000 living former players through Harvard's study, which receives funding from the NFLPA, Grashow and her colleagues have identified several elevated health risks for players.

Head injuries can cause high blood pressure, sleep apnea, low testosterone and depression, Grashow said. Oftentimes, players are living their post-career lives without treating those conditions, she said.

"It's so frustrating because it's like, we don't know what would happen if we actually treated the things that head injury caused," Grashow said. "We could see a totally different trajectory for these guys, but we haven't been doing that because I think there's such a tight coupling between the symptoms and the pathology and the hopelessness."

The league, players association and researchers overlap in their message to players about seeking healthcare as soon as symptoms arise, if not sooner.

In its Tuesday email entitled "New CTE Research: What Players Should Know," the union linked to more than half a dozen resources including a checklist that players can bring to doctor's appointments to ensure professionals are heeding the most common conditions that have been found in current and former players. 

From blood sugar and cholesterol to cognitive and emotional instability, the checklist aims to reduce players' need to research where they're most at risk.  

"Playing football puts players at risk for a number of conditions that, if untreated, will absolutely hurt their brains over time," Grashow said. "The good news is that a lot of what it does impact can be tested for, often treated and managed."

Research of former players’ brains often receives the most attention due to the fear, mystique and uncertainty surrounding degenerative brain conditions. But research of former players’ bodies have shown more mixed results, including some encouraging signs.

A 2018 study of 9,778 former NFL players who played at least one season between 1986 and 2012 found that former players’ mortality rates compared favorably to that of the general American male population. Former NFL players died at 46% the rate of U.S. men of the same age, race and calendar year, per the study published by the American College of Sports Medicine.

Former players in the study died at 65% the rate of their equivalent U.S. population from cardiovascular disease, the study found, a gap that widens far more for players with a body mass index that did not catapult them into the category of obesity. (Former players with Class 2 obesity or higher suffered from 2.2 times the cardiovascular disease-related deaths than the equivalent U.S. population.)

None of this erases the realities of research on players’ brains, nor is it likely to assuage concerns of players and families. But researchers caution against fear and hype that can further trigger players’ emotional unraveling or trust in medical professionals.

“I don't want to give people false hopes that treating these conditions are going to undo all the effects of football,” Grashow said. “But if we know that players are living with these conditions and not getting them treated, having cognitive symptoms, likely due in some part to those conditions and then getting scared that they have CTE and leading to suicidality, then I think we've missed an opportunity at least to try to address some of those conditions.”

Conversations around suicidal ideation have heightened during the last year after Cowboys defensive end Marshawn Kneeland and Minnesota Vikings receiver Rondale Moore died by suicide last November and February, respectively. Kneeland’s family donated his brain to Boston University’s CTE Center, which found Stage 1 CTE evidence in the 24-year-old’s brain. (CTE is diagnosed by severity from Stage 1 through Stage 4.) Documented concerns about Kneeland’s mental health had dated back to at least college, per records obtained by ESPN, and the Concussion and CTE Foundation emphasized that the diagnosis “should not be considered the cause of a suicide and is not known to be a risk factor for suicide.”

Still, foundation CEO Dr. Chris Nowinski noted that Kneeland’s CTE diagnosis came amid the league’s current era of helmet and safety advancements.

“We have no reason to believe the current generation is at a lower risk of CTE than previous generations,” Nowinski said in a statement. “Concussion protocols do not prevent CTE, because CTE is caused by repeated head impacts, not just concussions. If we want to reduce CTE risk, we must implement CTE prevention protocols and aggressively reduce the number and strength of head impacts at every level of the game.”

Conversations with NFL decision makers did not indicate the latest CTE research will spur any imminent rule or policy changes on the field. More research and awareness about proactive health measures during players’ lives appear to be a stronger focus.

There will be some who wonder how well data from a brain bank, donated by families of players who often had symptoms that prompted concern, represents the non-donating player population. Others will look at this 24.5% finding as more measured than a previous CTE Center study that found CTE in 99% (110 of 111) brains donated to the bank. Daneshvar was an author also on that study, which some believe was skewed. 

The authors of the latest study wrote in their finding that they hope this data analysis can “prove targets for future research studies and policy recommendations.” The study’s findings on the correlation between dementia and Stage 4 CTE at death could be among the topics on which researchers continue to seek clarity. Union warnings will continue to ring clear, too.

“Pay attention to your cognitive, neurological, and overall health,” the NFLPA wrote in its email to players. “If you have concerns, seek evaluation and support. Early intervention matters. Resources are available today that can help.”