My friend told me that helmets don't prevent concussions. If that's true, what's the point of wearing one when I ride my bike?
Here's why people wear helmets when biking, skiing, or doing other activities that can lead to head injuries: Helmets are a way to help protect your head from injuries like cuts and skull fractures. Always wear a helmet when doing any sport or activity where there's a chance you might hit your head against something like a tree, the ground, or another person.
Your friend is right: No helmet can prevent concussions. There's no way to keep the brain from moving inside the skull. If you hit your head hard enough, your brain can bang into the hard bone and cause a concussion.
Some "special" sports helmets and other new products claim that they can protect you from concussions. But studies don't back up these claims. As long as a helmet is right for your sport, hasn't been damaged, and is approved by the sport's governing body, it really doesn't matter how much it costs or how fancy it is.
Concussions aren't always preventable. But you can avoid other serious problems by taking care of yourself if you get one. If you take a hit to the head while playing sports, sit out the rest of the game and get advice from your doctor.