There is no drug that can fix the damage done by a concussion. About 20 percent of concussions lead to lasting problems but, until now, there hasn't been a way of predicting that. University of Pennsylvania researchers have developed a blood test to identify when concussions will lead to long-term problems. Results are preliminary but promising.

Douglas Smith, a professor of neurosurgery at Penn, said his team has found a protein present in the blood of individuals who had concussions and suffer from long-term cognitive problems.

"Well, we think the problem with concussion is really a diffuse axonal injury, it's a fancy term that means damage to the nerve fibers that allow one part of your brain to communicate with the other," he said.

"We think that with more extensive damage, there might be a release of this protein from the brain into the blood," Smith said. "That will tell us those individuals who might have had more damage and therefore have more cognitive dysfunction."

The blood test could be vital in finding the right patients for more focused research.

"If we find those individuals we now can ... run clinical trials to identify new therapies that will work, that will improve outcome for these patients," he said.

And, if the test works, it could help the search for a drug or therapy to treat concussions.

"We can then use this in the future to identify these patients who need these therapies and we can also improve our rehabilitation strategies for those patients," he said.

Smith said trials are necessary to confirm the effectiveness of the test, which was conducted on a small sample group. Then it might be ready for use in hospitals.