We already know how dangerous concussions are. But what about all the other head impacts our kids sustain while playing sports?

If your kid plays organized sports, two new studies will probably give you pause. In the first, researchers found measurable changes in kids' brains after just a single season of playing youth football, even without a concussion diagnosis. And in the second, they identified small changes in brain function immediately after a routine soccer practice in which players headed the ball.

While there's been much concern about the possible risks of brain injury due to concussion while playing youth sports, there hasn't been much research on the hundreds of head impacts that do not lead to a clinically diagnosed concussion—until now.

"We wanted to see if cumulative sub-concussive head impacts have any effects on the developing brain," explained Christopher T. Whitlow, M.D., Ph.D., M.H.A., who led the football study. Turns out, they do. After studying 25 male youth football players between the ages of 8 and 13, the researchers found that the more head blows a child sustained, the more changes were seen in their brain tissue—even when there was no concussion present.

It should be noted that the study is a small one, and we don't yet know whether the brain changes are permanent or will cause disease. Nevertheless, the groundbreaking news is certain to have some parents questioning whether the sport is worth the risk.

The news for soccer players is just as bad. Researchers from Scotland's University for Sporting Excellence had a group of youth players head a ball 20 times, testing their brain function and memory both before and after in order to see if their brains reacted instantly to repetitive impact. What they found was increased inhibition in the brain after just a single session of heading, plus memory test performance reduced by between 41 and 67 percent—though those effects self-corrected within 24 hours.

"Although the changes were temporary, we believe they are significant to brain health, particularly if they happen over and over again as they do in soccer ball heading," explained cognitive neuroscientist Dr. Magdalena Ietswaart. "With large numbers of people around the world participating in this sport, it is important that they are aware of what is happening inside the brain and the lasting effect this may have."

The takeaway? It's the hope that findings like these will eventually lead to the development of new approaches for monitoring cumulative brain injuries in youth sports. And in the meantime, parents of young players should probably proceed with caution.

Hollee Actman Becker is a freelance writer, blogger, and a mom. Check out her website holleeactmanbecker.com for more, and then follow her on Twitter at @holleewoodworld.