A new study provides further evidence of the potential long-term harms of head trauma, after finding that individuals who suffer a concussion in adolescence may be at greater risk of developing multiple sclerosis.

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Researchers suggest that concussion during adolescence could increase the risk of MS in later life.

Concussion is a form of traumatic brain injury (TBI) caused by a sudden blow or jolt to the head, which can interfere with brain functioning.

Signs and symptoms of concussion include loss of consciousness, dizziness, poor balance and coordination, changes in behavior and mood, memory problems, and confusion. Symptoms normally arise shortly after head injury, but they can sometimes take days to appear.

While concussion symptoms are usually short-lived, in recent years, research has shown that head trauma may have long-term implications for brain health.

One study reported by Medical News Today in 2015, for example, found that professional football players who experienced concussion were more likely to have memory impairments in later life than those who did not suffer concussion.

Now, researchers have identified a link between concussion in adolescence and later-life multiple sclerosis (MS) risk.

Lead author Prof. Scott Montgomery, of Oerebro University in Sweden, and colleagues recently reported their findings in the Annals of Neurology.

MS is a neurological disease estimated to affect around 2.3 million people across the globe.

The condition is believed to be triggered by an abnormal immune response, wherein the immune system mistakingly attacks and destroys myelin, which is a fatty substance that protects nerve fibers in the central nervous system.

For their study, Prof. Montgomery and colleagues used data from the national Swedish Patient and Multiple Sclerosis registers to identify 7,292 patients with MS. All subjects had been born from 1964 onward, and MS diagnoses were made between 1964 and 2012.

Each patient with MS was individually matched by sex, year of birth, age at MS diagnosis, and place of residence with 10 people who did not have MS. In total, the study included 80,212 participants.

Using data from the Swedish Patient Register, the team also identified any diagnosis of concussion among the participants during childhood (between birth and the age of 10 years) and adolescence (between the ages of 11 and 20 years).

The team found no association between concussion in childhood and the risk of MS in later life.

However, the study revealed that participants who experienced one concussion in adolescence were 22 percent more likely to receive a later-life MS diagnosis, while the risk of MS was increased more than twofold for those who suffered more than one concussion.

Previous research has indicated that trauma to the head may prompt an abnormal immune response that damages the brain. The authors speculate that this process might explain their findings.

“Head trauma in adolescence, particularly if repeated, is associated with a raised risk of future multiple sclerosis, possibly due to initiation of an autoimmune process in the central nervous system.”

Prof. Montgomery says that their findings provide “another reason to protect adolescents from head injury, particularly where they are at risk of repeated trauma, including from sports-related injuries.”

As per the Centers for Disease Control and Prevention (CDC), in 2012, a diagnosis of concussion or another form of TBI was made in around 329,290 individuals in the United States who were treated for sports- or recreational-related injuries.