Repeated head injuries, even if they do not result in concussion, can cause long-term brain damage, a study has found.
Researchers studied 67 American footballers, sampling their blood before and after playing.
They found those who suffered the greatest number of blows to the head had higher readings of a substance called serum S100B, which suggests an autoimmune response following a blood-brain barrier disruption.
This may explain why footballers, in particular, experience higher rates of brain damage.
Read more at University of Rochester