Or, to not have helmets at all, or much thinner helmets. Much like bare-knuckle or thin-padded gloves contribute to less "hard" hits being thrown in UFC than in boxing, or how Rugby players don't get the kind of brain injuries because they aren't smacking their heads into eachother as hard as football players are.
Helmets were introduced because a dozen plus kids were dying every year playing it due to things like skull fractures. Football is an inherently violent game and it is because of the rules not the helmets.
UFC: study that supports that assetion verses other factors like less money/rewards, shorter careers and full body contact? Different weight classes? Boxing vs Muay Thai? Yes, intuitively smaller gloves should contribute to less slow damage, but should also cause more acute and immediate injuries.
Yes, in the same way I'd argue for an abstinence-only education when it comes to repeatedly bashing your own head against the wall.