I don't think any standard helmet is going to protect you from concussion, which is essentially your brain suffering from the rapid acceleration/deceleration of your head hitting something or being hit by something. A helmet will protect you from penetrating injury or abrasions. Helmet deformation may mitigate this somewhat, but any impact that results in significant helmet deformation/damage is a potentially concussive event. My sons ex-girlfriend took a ball to the head during dodgeball, and a year later, she's still on concussion protocol and still dealing with symptoms.