In recent years, we've seen headlines about how concussion rates are on the rise, but that's been generally accepted as being a by-product of the fact that concussions are reported much more often than they were a decade or so ago.
A generation of children are being born to parents who grew up in an age when there was nothing to shake off about a head injury. The long-term effects on concussions are still being studied, but it's accepted now that a rattling brain inside a skull isn't a positive thing.
Last week, a study was published in the journal PLoS One by Laura Donaldson, Mark Asbridge and Michael D. Cusimano on the effects of the National Hockey League's rule changes on reported concussions. The rate of concussions, both reported and suspected, is still rising, which has led the authors of the study to conclude that the NHL's much-reported Rule 48 did not do enough to curb the effects:
The observation that concussion incidence was unchanged between 2010–11 and 2011–12, when the broader version of Rule 48 was introduced suggests that penalizing intentional checking to the head may not be effective on its own as a strategy to reduce concussion incidence. [PLoS One]
Held up against similar numbers of concussions, suspected concussions, and facial fractures at the Ontario Hockey League-level, it was found that there's a similar number of concussions per 100 games (5.23 in the NHL versus 5.05 in the OHL). Neither number has decreased between 2010 and today.
Looking at it from an OHL perspective, David Branch takes some heat for his harsh penalization of head hits. The best example may be from a season ago when Mike Halmo of the Owen Sound Attack received ten games for catching Nail Yakupov with his head down, a ruling that drew some confusing and criticism directed at OHL brass:
Would it have been a blindside hit under NHL standards? The authors of the study don't seem to think so, stating that "a rule can have no effect unless it is enforced, and a lack of enforcement was suggested by the observation that checking to the head penalties were called 10-fold less often per game in the NHL in 2011-12."
So if it isn't hits to the head that is causing concussions, what is? Quite obviously, fighting and illegal bodychecks into the boards. It's notable that taller players were at less risk of concussion in the OHL, likely because their heads don't hit the glass or boards with as much force as a smaller player would. As for fighting, it was the most commonly called penalty (along with the rarely-called "check to the head" penalty in the NHL) that happened at the same time as a concussion in the OHL.
Again, fighting on the decline in junior hockey isn't much of an attention-grabbing headline anymore, but running the numbers on fights between 2012 and 2013, what was notable was that fights per game in the OHL declined at a higher rate than those in other two major junior leagues in Canada. Between seasons, fights in the OHL fell off close to 24% from 0.92 fights per game in 2012 to 0.70 in 2013. In the Quebec league, they dropped 15% from 0.78 to 0.67, and in the Western league, from 1.00 to 0.84, or a 16% drop. (per HockeyFights.net)
Perhaps that isn't an indication of a trend, but the 10-fight rule introduced in the OHL obviously had somewhat of an effect. Take a look at the Windsor Spitfires. Ty Bilcke fought 37 times in 2012, but just 10 times in 2013. Only Emerson Clark surpassed 10 fights, but the kicker is that the total number of Spitfires with at least one fight dropped from 20 to 18—it's not as though there were people stepping in to take Bilcke's job from him once he hit the limit.
So that could be an avenue for the NHL to explore. If anything, the study shows that the NHL is on the wrong track in attempting to curb its concussion problem, while the OHL is a step ahead. It penalizes more players and is much stricter with discipline.
Looking at the Halmo hit again, and the Brayden McNabb hit on Joey Hishon in the 2011 MasterCard Memorial Cup that ended Hishon's junior career, it's obvious that it isn't just blindside hits that cause injuries. It could take years for a new culture less focused on violence to take over hockey, and in the interim, the sport needs strict enforcement of the current rules to get by.