Here’s yet another reason to protect young athletes from head trauma: A large-scale new study found that concussions in adolescents can increase the risk of later developing multiple sclerosis. The risk of multiple sclerosis, or M.S., an autoimmune nervous system disorder with an unknown cause, was especially high if there were more than one head injury.

The overall chances that a young athlete who has had one or more head injuries will develop multiple sclerosis still remain low, the study’s authors point out. But the risk is significantly higher than if a young person never experiences a serious blow to the head.

The drumbeat of worrying news about concussions and their consequences has been rising in recent years, as most of us know, especially if we have children who play contact sports. Much of this concern has centered on possible links between repeated concussions and chronic traumatic encephalopathy, a serious, degenerative brain disease that affects the ability to think.

But there have been hints that head trauma might also be linked to the development of other conditions, including multiple sclerosis. Past studies with animals have shown that trauma to the central nervous system, including the brain, may jump-start the kind of autoimmune reactions that underlie multiple sclerosis. (In the disease, the body’s immune system begins to attack the fatty sheaths that enwrap and protect nerve fibers, leaving them vulnerable to damage and scarring.)