A football helmet, with its health warning sticker, placed on the field in memory of former NFL player Junior Seau at Oceanside High School in 2012. Seau played for Oceanside, then USC and the Miami Dolphins. He suffered from chronic brain damage from football and committed suicide last year. (Mike Blake / Reuters)

After each of the six seasons I played in the National Football League — 2003 to 2008 — I held on to my helmet as a keepsake. I have since examined those helmets more closely than I ever did while banging heads as a tight end for the Denver Broncos. Just behind and underneath the right earhole is a small, clear sticker. In tiny print, it reads:

“WARNING: NO HELMET CAN PREVENT SERIOUS HEAD OR NECK INJURIES A PLAYER MIGHT RECEIVE WHILE PARTICIPATING IN FOOTBALL. Do not use this helmet to butt, ram, or spear an opposing player. This is in violation of football rules and such use can result in severe head or neck injuries, paralysis or death to you and possible injury to your opponent. Contact in football may result in CONCUSSION-BRAIN INJURY which no helmet can prevent. . . . Ignoring this warning may lead to another and more serious or fatal brain injury.”

Plain enough. But no one pointed it out. And never do I remember even a cursory discussion of head injuries. Our athletic trainers never brought up the subject. Our team doctors didn’t, either. Our trainers and doctors gave us one talk a year, at the beginning of training camp. They told us to report our injuries, to show up on time for treatment sessions and to make sure we passed the drug tests. This was guidance intended to keep us using our heads on the field — not off.

The NFL sells violent entertainment but keeps it nice and tidy. Networks cut to a commercial when the actors start dripping blood. As long as no one sees it, there are no consequences: There is only the next play. In “League of Denial,” the consequences are the story. Instead of cutting away, Mark Fainaru-Wada and former Washington Post reporter Steve Fainaru zoom in on every tau-protein-riddled brain-tissue slide, every hasty NFL rebuttal and every self-inflicted gunshot wound to the chest. The devil is in the details: every page a new demon.

Joe Maroon, the NFL’s first brain specialist, lays out the threat to the league: “If only 10 percent of mothers in America begin to conceive of football as a dangerous game, that is the end of football.” Whether or not that’s hyperbole, the sentiment sets the stage for a scientific battle over the football player’s brain and establishes what the NFL is risking if the evidence becomes public.

The Fainaru brothers liken the NFL’s denials to Big Tobacco’s old claims that smoking wasn’t bad for you. Turns out it kills. But it also turns out that people still smoke, illuminating an interesting case study in human behavior — one that the NFL might be inclined to consider. Morbidity does not scare people away. In fact, if our co-authors’ interest in the subject is any indication, it draws them closer.

The book begins with the 2002 autopsy of former Pittsburgh Steelers great Mike Webster that turned up a curious disease in his 50-year-old brain. Chronic traumatic encephalopathy (CTE) was known in the medical community but traditionally tied to boxers, not football players. Formerly called dementia pugilistica, CTE is a degenerative brain disease, resulting from repetitive head trauma, that some believe causes symptoms of dementia, such as memory loss, aggression and depression. Before Webster’s autopsy, it was thought that the football helmet protected the brain and that brain injuries were not a problem in the sport. For Webster’s family, the new findings helped explain his rapid descent into madness, and they also set the stage for a scientific battle over football players’ brains. The NFL knew exactly what was happening to the brains of its workers, the Fainaru brothers argue, yet withheld this information for fear it might topple the league.

As the authors report, dead football players’ brains were being sliced open; diseases discovered; connections made; foundations and partnerships formed; academic papers published, republished, debunked, rewritten; grants awarded; more brains sliced; lawyers hired; and lines in the sand drawn over and over again between those at war over football brain damage. This debate was going on somewhere else, far away from those of us on the field. And whoever was involved didn’t think we needed to know.

This book was depressing for me to read and extremely difficult to get through. Not because of the quality of the work — it is meticulously researched, artfully structured, engaging and well written. It is depressing because of the conclusion, which is fairly simple: Football causes CTE, and CTE causes severe cognitive impairment, including dementia and depression. For those affected, life unravels.

To highlight the macabre implications, “League of Denial” hangs on the profiles of some of the game’s most thoroughly ravaged players: Mike Webster, Dave Duerson and Junior Seau. The fairy-tale NFL life did not end well for these men. The latter two shot themselves in the chest, presumably to preserve their brains to be studied for a disease they were convinced they had. They were right.

But there’s another aspect to the psychological decline of former football players. My sincere belief is that these men are as tormented by their loss of identity as by any buildup of tau proteins. Of course, they will tell you that the despair is a function of those tau proteins, that a physical brain change leads to depression and suicidal thoughts. And they may be right. But let us also consider the unquantifiable darkness.

A popular question presented to former players in light of the CTE findings is: Knowing what you know now, would you do it all over again? Yes, says the man with his finger on the trigger and the muzzle pressed against his chest, trophies and awards and jerseys scattered around him, a suicide note on the dresser. Yes, because what else is there and who else am I but this? Yes, because I achieved my dream. I did it. It’s done. So what else is there to do but die?

Admitting to having suicidal thoughts isn’t easy, but we have heard former players speak up lately. It’s safe to assume that a small percentage of those who think about killing themselves actually talk about it. So it should give us pause when we hear our former football heroes open up about their suicidal thoughts. It should make us consider the football myth we tell ourselves. It should make us question the motives of those who sell us the sport.

Suicide and depression are not NFL problems: They are human problems. I’ve known a handful of people who have killed themselves; none were football players. The contradictions become too heavy; the promise of the outside world gets torched in the brutal hive of the mind, and only one choice remains. We’ve become accustomed to viewing suicide within a familiar framework, and when something breaks the mold, we look to figure out why. “League of Denial” blames CTE. Why else would a hero want to die?

It is important to study the physical effects of head trauma on depression and suicide, but equally important to consider the psychological trauma of the football player’s post-career identity crisis. In the NFL, the industry writes a fairy tale to sell the game. The athlete is the actor. He plays along; he knows his lines well. But with every platitudinous sound bite and “yes, coach,” the gap between perception and reality widens, pulling him further and further from his true self. Just how far isn’t apparent until his helmet comes off for good and he finds himself alone in the woods. The result is a frightening depression and an identity crisis. But football men are proud and stubborn. They will tell no one.

My only concern with this book and with the head-trauma discussion as a whole is that they will legitimize the suicidal tendencies of former players, will affirm the science of their demons and will give some men a green light to end a suffering that “League of Denial” guarantees will only get worse. For non-football-players, this is an informative, intriguing and sobering book about power and control. I recommend it strongly. For football players, it reads as a death sentence. I encourage my brothers not to open it.

Nate Jackson is the author of “Slow Getting Up: A Story of NFL Survival From the Bottom of the Pile.”


The NFL, Concussions, and the Battle for Truth

By Mark Fainaru-Wada and Steve Fainaru

Crown Archetype. 399 pp. $27