A "violent jolt" to the head of a schoolboy rugby player can cause serious damage to critical blood vessels linked to the brain which could have consequences for their emotional development.
It could also result in serious concentration problems in the classroom, according to Professor Sabina Brennan, a psychologist at Trinity College.
Her comments come as the Sunday Independent confirmed that the Government was drawing up new guidelines for grassroots players who suffer concussion on the pitch.
Dr Brennan said concussion was a mild traumatic brain injury, arising from the organ being "violently jolted" in the skull.
"As a consequence of that, the brain cells, and the blood vessels that supply them with nutrients and oxygen vital for survival, can actually be damaged," she said.
"A whole series of biochemical reactions are set off that prevent the brain from functioning properly.
"It's been described as an energy crisis - the cells can't get the energy that they need to function at an optimal level. That can last for weeks after an injury."
Dr Brennan stressed the need for more research in order to better understand the long-term consequences of repeated head trauma.
She also pointed out that difficulties with concentration in the classroom, issues with problem solving, and mood and anger management problems could be as a result of an undiagnosed brain injury suffered on the pitch.
"It can be hard for a teacher, or parent, to relate the problems a teenager might be displaying, to an injury incurred playing sport," she added.
"Suddenly they become the kind of child who's not paying attention at school, and always in trouble. It concerns me that link is not there.
"They don't link the two. But the fact of the matter is that it could be a consequence of an injury.
Dr Brennan said it might be "very naïve" to think a certain form of head injury could be without consequence.
"Nobody expects to get away with repeatedly breaking a leg, or spraining an ankle, without being left with some sort of impairment, if they don't give it enough time to recover," she added.
"Scientists are still learning how the brain works. I think we need more research, education, greater awareness and public policy. In the interim, we need to be mature and make decisions about what needs to be done. Erring on the side of caution is probably wise."
While she stressed that exercise had many benefits, she said there was an urgent need to "minimise the risk" of serious long-term damage to teenagers who suffer head trauma.
Dr Brennan also pointed out that the "conversation" on brain injuries should cover all contact sports, including soccer and Gaelic games.
Meanwhile, the Department of Education confirmed it is working with other departments and stakeholders to develop new 'concussion guidance' for the general public.
"The guidance will be appropriate for use in schools. It will take account of best practice in educating people about concussion and creating better awareness about injury prevention," a statement said.
The advice would consider "best practice" in educating the public about the condition, it added.