"We would have been very happy if the results had been negative, but multiple areas of Chris Henry's brain showed CTE," said Julian Bailes, director of BIRI and chairman of neurosurgery at West Virginia. Bailes and his colleagues presented results of their forensic examination at a news conference Monday afternoon.

Researchers have now discovered CTE in the brains of more than 50 deceased former athletes, including more than a dozen NFL and college players, pro wrestler Chris Benoit and NHL player Reggie Fleming.

Repeated blows to the head are the only known cause of CTE, researchers say. Concussive hits can trigger a buildup of toxic tau protein within the brain, which in turn can create damaging tangles and threads in the neural fibers that connect brain tissue. Victims can lose control of their impulses, suffer depression and memory loss, and ultimately develop dementia.

At the news conference Monday, Bailes said that neither NFL nor WVU records show Henry was diagnosed with a concussion during his playing career.

But it doesn't take a collision with another player for brain trauma to occur.

"The brain floats freely in your skull," said Bennet Omalu, a neuropathologist who is co-director of BIRI. "If you're moving very quickly and suddenly stop, the brain bounces."

While the links between CTE and behavior are still being studied, many of the former athletes diagnosed with this form of brain damage died under unusual circumstances. Ex-Steeler Justin Strzelczyk, for example, was killed in 2004 after experiencing hallucinations, leading police on a high-speed chase for 40 miles before driving his car into a tanker truck. In 2007, Benoit strangled his wife and 7-year-old son, then put Bibles next to their bodies and hanged himself. Tom McHale, a guard for three NFL teams remembered by teammates as smart and dependable, sank into depression and died of a multiple-drug overdose in 2008.

Henry, 26, died on Dec. 17, 2009, a day after he either jumped or fell from the back of a moving pickup truck being driven by his fiancée, Loleini Tonga. The two had been involved in a dispute before Tonga got into the truck and Henry jumped in. One witness told reporters that Henry said, "If you take off, I'm going to jump off the truck and kill myself."

It is still not clear whether Henry jumped or fell, but as Tonga was driving at about 19 mph, Henry crashed to the ground, suffering a fractured skull and massive head injuries. Police ruled the incident an accident. No traces of alcohol were found in a toxicology report, which didn't include any other tests for drugs. No charges were filed against Tonga.

After Henry's death, his mother, Carolyn Henry Glaspy, gave BIRI permission to examine his brain in detail.

CTE can be pinpointed only by autopsy, and even under regular postmortem analysis, its effects are invisible. But using cell-staining techniques discovered and developed by Omalu, scientists can see the dangerous tau proteins and telltale tangles that characterize CTE. After staining, normal brain cells are blue and uncluttered under a microscope, while Henry's brain cells were discolored, clumpy and filled with threads, according to the researchers.

Now, Bailes -- and likely Henry's family, friends and fans -- will wonder if his neural damage contributed to his emotional volatility, including whatever problems he was suffering the day he died.

"I think it did," Bailes said. "Superimposed on the acute brain injuries Chris suffered when he died, there was fairly extensive damage throughout his brain that was fully consistent with CTE. This syndrome is expressed not only as changes in the brain, but clinically, as behavioral changes. And starting with Mike Webster, we have seen common threads in these cases: emotional disturbances, depression, failed personal relationships and businesses, suicidal thoughts, sometimes alcohol or drug use."

"I'm just trying to learn what happened, and what the situation was with Chris' brain," Glaspy told ESPN.com on Sunday. "Whatever I can do to help anyone else who is going through this, I'm willing to do."

At the news conference, Glaspy said the results were a "big shock" because she knew nothing about her 26-year-old son's underlying condition or the disease.

"I was a little scared," she said. "It was something new to me. I'm still trying to educate myself as to what it means. Some of it makes sense with some of the behavioral patterns in Chris -- just like mood swings and the headaches.

"Hopefully I can share whatever they share with me with other parents and help the NFL deal with the matter of being hit in the head and concussions and to educate ourselves as mothers and fathers when we send our kids out there on the field."

For years, the NFL and its affiliated researchers disputed scientific evidence linking concussions to long-term brain damage. However, referring to reports of CTE among former players, NFL Head, Neck and Spine Committee co-chair Richard Ellenbogen told The New York Times earlier this month, "They aren't assertions or hype -- they are facts."

In April, the league announced a $1 million gift to the Center for the Study of Traumatic Encephalopathy at Boston University.

Henry, a native of Belle Chasse, La., played collegiately at West Virginia and was a third-round pick by the Bengals in 2005. He played for five tumultuous seasons in the NFL; he was arrested five times during his pro career, and NFL commissioner Roger Goodell suspended him for the first half of the 2007 season for violating the league's personal conduct policy.

But after Cincinnati brought him back in 2008, Henry vowed to put his substance abuse and anger management issues behind him. And he had been succeeding, according to teammates as well as Bengals officials.

Bailes, a former Pittsburgh Steelers team doctor and currently the team doctor for West Virginia, said his quest is to make football safer.

"I think football is a great sport, and we want to make it safer," Bailes said, "but we have to continue to move forward with changes made recently and take the head impacts out of the sport as much as possible."

Peter Keating is a senior writer for ESPN The Magazine. His blog appears on ESPN.com. Information from The Associated Press is included in this report.