The issue with those studies is that they don't really account for more modern views about brain injuries. We know that boxers suffer "serious" head trauma more

The issue with those studies is that they don't really account for more modern views about brain injuries. We know that boxers suffer "serious" head trauma more frequently but lots of modern research suggests small repeated head trauma is as dangerous. Incidents of cte for instance in soccer maybe accounted for by heading drills. Which is why talks about concussions isn't enough. I'd still expect MMA to be safer in this regard than boxing but there is enough head banging events in things like gaurd practice that don't occur during normal boxing practice that I wouldn't be shocked to learn MMA has as serious a problem with CTE as boxing.