Are Helmets Really Making Things Worse?

One of our listeners wrote in to ask about american football, and wondering helmets actually make American football more dangerous. The idea being that football players wouldn't be so rough on each other if they weren't wearing helmets. Is there a lot of evidence for it? Andth i think that is an intriguing case, although i would say it's far from proving but there is this idea that people are now getting concussions and having more long term damaged than would happen if we went back, say, to the old leather helmets they used to wear back in the 19 tens and twenties.