Widespread panic. That's how Jennifer Smith describes the days after 43-year-old Junior Seau took his own life with a bullet to the chest.

Smith is the director of player programs for Pain Alternatives Solutions and Treatments (PAST), a coalition of New Jersey--based doctors and facilities that offers former athletes pro bono health care. Suddenly the PAST help line was swamped with calls from retired NFL players fearful that they might become the next Seau or the next Dave Duerson, the former Bears safety who shot himself in the chest last year and left a note asking that his brain be given to science.

"To be totally honest, I am scared to death," says Ray Lucas, a PAST patient who suffered numerous concussions while playing quarterback and special teams for the Patriots, Jets and Dolphins from 1996 to 2002. "I saw Junior a year ago, and he was upbeat and bubbly."

Seau did not appear to suffer a protracted psychological unraveling in the manner of Hall of Fame center Mike Webster, who was homeless at times after leaving the league. Webster died at age 50 in 2002, and he was later found to have chronic traumatic encephalopathy (CTE), the buildup of protein in the brain that has been associated with dementia in football players. Retired players see Seau's act as impulsive, which makes it more frightening—the areas of the frontal lobe that are damaged in players with CTE are associated with impulse control.

Even players who had long careers but are thriving postretirement are chilled. "I was shaken by it," says Amani Toomer, a Giants receiver for 13 years who now works a full broadcasting schedule. "He was such a happy guy. It puts in perspective that it doesn't matter your actual state if there's something wrong with your brain. That's what's scary: You could be doing well, and [problems start] to seep in."

Seau's family will likely donate his brain for research; everyone expects it to show the telltale brown splotches that indicate CTE. He played 20 years in the NFL as a sledgehammer of a linebacker, and CTE has been found even in deceased high school and college players whose football experience was significantly briefer—most notably Owen Thomas, a Penn defensive end who killed himself in 2010 at age 21. One part of the story is known: The brains of long-time players that are dissected nearly all show CTE. But evidence for the direct, causal link between CTE and suicide that has stoked fear among retired football players remains equivocal. In Thomas's case, Dr. Robert Cantu, codirector of Boston University's Center for the Study of Traumatic Encephalopathy, said that "not enough [CTE] was there to affect behavior."

Most of the coverage that mentioned CTE in the wake of Seau's death described it as a "progressive" and "degenerative" illness. But the scientists who have examined the brains of deceased players see only a snapshot—they infer the disease's progressive nature from the deterioration of the athlete's behavior. In fact, just how tightly CTE is linked to depression or suicide is unknown. Joseph Battaglia, director of psychiatry for PAST, says that for some players he has worked with, symptoms actually improve as they get further from football, particularly if they receive treatment such as changes in medication or diet, cognitive and behavioral therapy, cardiovascular exercise and peer-group support. "Their process is a little different over time than progressive diseases like Alzheimer's," he says. (With Alzheimer's, a patient's brain deteriorates until death, no matter the medical attention.)

Thus far the few large studies of retired NFL players indicate that they have a higher prevalence of depression than the general population but not by much, and the disparity decreases among older age groups. Kevin Guskiewicz, a neuroscientist, athletic trainer and director of North Carolina's Center for the Study of Retired Athletes, has surveyed more than 3,000 players since 2001. He found that 14% of players aged 35--44 suffered depression at some point in their lives, compared with 8% of all males in that age group, but the disparity narrows in older cohorts. A separate 2007 study cowritten by Guskiewicz found that players who sustained three or more concussions were much more likely to be diagnosed with depression than those with fewer concussions, but that the overall prevalence of depression among 2,552 retired players was 11.1%, just 3.1% higher than the general male population. "We've certainly got a few folks who are depressed," Guskiewicz says, "but the majority of them are not."

The findings fit with military research. Jordan Grafman, a neuropsychologist who has studied Vietnam veterans with brain injuries, says that "the suicide rate among people with a documented brain injury might be slightly higher, but it's certainly not a great deal higher in the vets we've studied." Adds Grafman, "There are areas of the frontal lobe that, when damaged, make it more likely sometimes that you'll be depressed. And other areas, if they're injured, will make you less vulnerable to depression."

In another study of retired NFL players conducted by University of Michigan researchers (one co-author was former Lions QB Eric Hipple), 14.7% of the 1,617 subjects were found to have experienced moderate to severe depression, and players who were dealing with pain from musculoskeletal injuries and depression at the same time were suffering the most. "We've gone down the path of blaming only concussions for all the troubles of retired players," says Thomas Schwenk, lead author of that study and now dean of the University of Nevada School of Medicine. He argues that potential contributing factors are manifold. "[Former players] lose their identity, they have chronic pain, they stop exercising, and they fall apart. But our study came out right when the concussion work was getting big, and the NFLPA dropped us and went in the direction of the concussion work."

It may never be known what constellation of ills Seau was confronting. He was revered for playing through injuries. And, said former USC coach Pete Carroll, "he wanted to play forever." In fact, Seau's first retirement lasted just four days—he announced he was leaving the game on Aug. 14, 2006, only to sign with the Patriots less than a week later. In 2010 he announced his intention to retire for a second time, saying he planned to "go surf." "A lot of guys say, 'Now I can get back to fishing and golfing and hunting,'" says Ken Ruettgers, a Packers tackle from 1985 to '96 who wrote his 2007 Ph.D. dissertation on the difficulties NFL players have in transitioning from football. "That lasts for about a season, and then they get bored."

Ruettgers now works with recent NFL retirees and suggests an array of interventions, most commonly marriage counseling. "When your life changes like that, so does your relationship," he says. "It's almost like having to get remarried."

Brain-trauma experts who spoke with SI hoped Seau's legacy would not be fear among players about an unstoppable decline into depression but rather renewed efforts to track players and all their complex issues. "Americans are interested in very reductionist explanations, but I would consider the concussion issue the tip of the iceberg" with regard to depression, Schwenk says. "And the iceberg is the reservoir of misery these people have."



NO WARNING The seeming impulsiveness of Seau's final act—he did not suffer a long unraveling like other players—compounded the mystery surrounding his death.