Repeated concussions can increase the thickness of the bones of the skull and make it more dense. This conclusion was made by Australian scientists from Monash University.
It seems that there is nothing good in repeated head injuries, but now scientists from Australia have proven that because of them the skull is becoming denser. True, the researchers themselves are not sure whether the armored skull provides us with any additional protection. It was found that if a small weight was occasionally dropped on the head of laboratory rats, which stimulated the symptoms of a concussion, after recovery they had a stronger skull.
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Researchers believe that the body works in this way to strengthen the protection of the brain – the most important organ in animals. The research team was unable to determine whether this extra thickness actually reduces the likelihood of future brain injuries.
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Let's note that concussions and craniocerebral injuries are well studied by science. But too little research has been done on the body's natural response to them, as well as its built-in defenses against such injuries. Science has long ignored the skull's potential impact on concussions and the mechanisms by which it defends itself against this threat. New evidence suggests that the skull may be considered an important factor in the effects of repetitive concussions. (READ MORE) 
Monash University
Medicine
Australian public university located primarily in Melbourne ( Victoria)