Fighting is down in the NHL. But it's not because tough guys are worrying about brain injuries.

"I don't think guys are less willing - it's just not as big of a part of the game as it used to be," Columbus Blue Jackets forward Jared Boll said.

Boll has more than 80 fights over the past four seasons, and he says he doesn't worry about the concussion issue. USA TODAY research showed one concussion this season resulted from a fight.

But fighters have another worry in a Boston University research center study of the brains of deceased NHL tough guys Bob Probert and Derek Boogaard, which showed evidence of chronic traumatic encephalopathy (CTE).

That disease has been linked to depression and severe dementia.

"It's pretty scary to see," Boll said. "But I wonder what the brain of a guy who doesn't fight but gets hit a lot would look like. I just try to stay healthy, and if I wasn't feeling right, I would say something."

Paul Bissonnette, a popular tough guy with more than 190,000 Twitter followers, says he doesn't see many concussions caused by fighting, and "there are plenty caused by little runts running around with elbows."

The Phoenix Coyotes forward says he worries more about the stress of his position. "I sit out a lot, and it eats away at me," he said. "Can't depression result from that? Do they research that?"

Taking a modern approach, he said he has consulted a sports psychologist to help him stay positive even if he isn't playing.

"I think guys who fight and play a limited role spend a lot of time by themselves, and that isn't a good thing," he said. "You start to question yourself."

He has tried to prepare himself for the possibility that fighting was becoming less important around the league.

"When I came in, I noticed the game was changing, and I've been working on my game," Bissonnette said. "In the summer, I don't go into kick-boxing and fight UFC to become a better fighter. I try to become a better hockey player."