Gloves unfortunately probably do more damage than not. Prior to gloves, you didn't want to punch someone in the head too hard, as you'd likely break your hand. Heavier gloves used these days allow you to do so with little chance of breaking your hand. Over time, this causes dementia pugilistica.
Ironically, MMA, which is more "violent", is less likely to be as unhealthy as boxing. Fewer blows to the head than boxing over the length of a career, but it is still obviously a concern.