Helmets “certainly help to mitigate forces that are distributed by impact to the skull and the intracranial cavity and the brain,” said Kevin Guskiewicz, a professor of sports science at North Carolina. “But the brain is still going to move inside that cranial cavity regardless of whether there’s a helmet on or not.”

Guskiewicz believes “behavior modification” such as not “leading with the head” when tackling in football can prevent concussions as much as improved helmet design.