The University of California, San Francisco is addressing the problem by looking at high school athletes.
"He got to the ball first, looked up and just clipped my head on the temple," said UCSF patient Gary Lee.
He enjoys his time on the basketball court, but a head injury could have put an end to his days of shooting hoops. After days of having a headache, he went looking for answers.
"The headaches I got though weren't the kind of headaches you get when you have the flu. Like, I didn't feel congested, I just felt kind of sluggish and out of it all the time," said Lee.
Doctors say ignoring head trauma injury is common among teens because head injuries and concussions often seem like concerns that only plague professional athletes. But anyone who plays sports can wind up with a bump that's much more than a bruise.
In 2009, Matt Blea, a football player at San Jose Academy, suffered a critical head injury when he was hit by an opposing player as he tried to catch a pass. Blea got up slowly and other players helped him to the sidelines. Blea then collapsed.
He was taken away in critical condition and spent 23 days in the hospital; eight of them in an induced coma. After brain surgery, the teenager came home; looking fit but still dealt with some of the problems associated with being hit.
Lee can relate. He's part of a concussion clinic at UCSF that studies the long and short term effects of head trauma.
"We are at the beginning of traumatic brain injury research," said Vice-chair of neurosurgery at UCSF Dr. Geoffrey Manley.
Manley says high school athletes, and even the pros like former 49er quarterback Alex Smith, can suffer injuries with long-term effects. He says research and monitoring are essential because athletes continue to play sports and many of them continue to get hurt.
"That's really what this clinic is all about, is to bring the highest, cutting edge level of care to people today. So, that as we're learning about things through our research, we're immediately applying that to patients," said Manley.
All concussions are serious and ignoring the signs and symptoms increases the risk of suffering another, more serious, head injury. As with Lee, the signs of serious head injury don't always appear immediately. If something doesn't feel right, get it checked immediately.
"Just go see, like a doctor, [because] it's really not worth it," said Lee.