Probably more so for the grinders and fighters that were more prevalent in the decades before 2000. The game has changed a lot since then with speed and finesse emphasized over big hits and fights. Not that they don't occur in the modern game, they are just not as common. Back in the day each team had an enforcer who protected the star players and usually the fourth line was the hitting and grinding line. I'd say the concussions were more common and players would regularly play through those types of injuries.
The NHL decided awhile ago to try and cut back on the fighting and rough stuff. There's also been a natural progression in the game where speedy players became more valuable than hitters and riders; the latter couldn't keep up. Teams that tried to play that style weren't able to be as successful as teams that valued speed and finesse. Not to say that fighting and heavy hits aren't more prevalent at the lower professional ranks (AHL and ECHL) but I don't see as much rough stuff as there used to be at the NHL level. Modern fights look more like wrestling matches than the fist fights/brawling that I remember back in the 70s and 80s.
Hockey's a rough game. Players are bigger and faster than they were 30 years ago. Collisions do happen and there are vicious hits that sporadically occur during a game. Overall the NHL seems committed to protecting their players (and most players police their own ranks given the amount of money that's on the table).
What would be interesting is to see how much difference there is between the brains of male and female hockey players. Women make up a sizable portion of hockey players at the youth and college level. I've never watched much women's hockey but I'd suspect there's less hitting and the players tend to be much smaller than the male side; most women collegiate rosters list women under 5'5".
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