"The first sample is recommended to be taken 10-14 days after the concussion. This allows us to see the magnitude of the injury, and gives an idea of how long the healing process will be," according to the researcher.

Further, the results also show that repetitive head trauma in boxing, damages nerve cells in the brain, even though the boxer may not show any concussion symptoms.

"The assessment today is often based on physical symptoms, neuropsychological tests, and the neurological examination of the athlete," said Neselius.

"Our studies show that these tests are not sensitive enough, nor can we rely on the athletes self-reported lack of symptoms. Concussion symptoms usually pass after a few days, but the neurological damage may still be present," she added.

Concussion is one of the most common sports-related injuries, and more athletes experience it every year. In recent years, focus has been directed on the effects of repeated concussions, in which athletes in such sports as ice hockey may be affected by long-term effects.

"I hope that brain injury markers in the cerebrospinal fluid, and hopefully also later in blood, can be used at all levels in all sports. By this we can use individual measurements to plan and guarantee safe rehabilitation," said Neselius.