Parents, beware - if you're thinking of sending your children to the kick-boxing or taekwondo class, you may want to think again. A new study reveals that young athletes who play contact sports may experience memory problems and suffer from brain damage even without diagnosis of concussion.

A study published, Wednesday, in the journal Neurology reveals that repeated blow to the head during a season of contact sports can cause players to experience memory and cognition problems even if the impacts did not result in a concussion. Those who experienced the most hits to the head or body also experienced more changes on the brain's white matter which is made up of nerve fibers that function as the brain's communication cables.

The study was conducted on two groups of Dartmouth College athletes. One group is consist of 80 football and ice hockey players and the other group was made up of 79 athletes who play track, crew and cross-country skiing.

The athletes were scanned with a new type of MRI at the beginning of the season and took a test of cognition and memory. Members of the contact sports groups wore helmets equipped with accelerometers so researchers can compile the number and severity of impacts in their head. Players who sustained a concussion during the season were excluded in the analysis.

At the end of the season, the athletes were scanned again and researchers observed brain pattern changes in the ones who played contact sports.

Dr. Thomas McAllister, who conducted the research while affiliated with Dartmouth College, said that even when there is no concussion, hits that jolt the brain can cause changes in the white matter. "And [the changes] are related to the frequency and intensity of hits. And the degree of change is correlated with poorer performance on a measure of cognition," he explains.

Brain injury experts called the new study important and timely. "I think this is the next big bomb to drop," said Dr. Robert Cantu, co-director of the Center for the Study of Chronic Traumatic Encephalopathy. "This study shows that you can have brain injury without a recognized concussion."

The results of the study also suggest that some individuals may be more susceptible to repeated head impacts that do not involve concussion but more research is needed to identify them.