The introduction of an autoimmune process in the central nervous system may be the culprit of the association between head trauma and MS.
Adolescent head trauma — such as concussions – has been linked to an increased risk of developing multiple sclerosis (MS) later in life, according to a new study.
Researchers from Sweden conducted an analysis in order to determine whether concussion in childhood or adolescence is linked to later MS risk, explaining that previously published literature indicates some association, but methodological limitations in those reports included only retrospective data and small study populations.
“Not only did we see a greater MS risk with an increasing number of concussions, we also saw increasing MS risk with increasing duration of hospital admission for concussion, as an indicator of central nervous system (CNS) trauma severity,” study author Scott Montgomery, BSc, PhD, told MD Magazine. “The lack of association between limb fractures in adolescence and MS indicates that CNS trauma, rather than other types of injury, are important. It is therefore unlikely that the results are due to more frequent accidents caused by pre-symptomatic MS.”
In their study, the researchers used the Swedish Patient Register and the MS Register to identify all MS diagnoses through 2012, totaling 7292 patients with MS, all born after 1964. Each patient was matched individually with 10 people without MS by sex, year of birth, age or vital status at MS diagnosis, and region of residence by county. The entire study population totaled more than 80000 patients.
Additionally, data were collected about concussion diagnoses and control diagnoses of broken limb bones from the Patient Register from birth to age 10 years, or separately from age 11 to 20 years.
Overall, there were a higher proportion of women, which the researchers said was consistent with the sex ratio in MS diagnoses. The data also showed a difference in level in education: higher education was linked to lower MS risk, but it did not appear to be statistically significant, according to the study authors.
The researchers determined that neither concussion nor limb trauma in the years from birth to age 10 years was linked to future development of MS, however, concussion in adolescence between the ages of 11 and 20 was linked to MS diagnosis. Additionally, they found that this relationship showed a dose-dependent association, where the more concussion diagnoses an adolescent had led to a greater MS risk.
As for how physicians can best use these new findings in their own practice, Dr. Montgomery said his team’s conclusion are yet another reason to advocate for protecting adolescents from head injuries.
“Teenagers who experience a concussion should be encouraged strongly to avoid putting themselves at risk of subsequent head injuries,” Dr. Montgomery added. “Only a small proportion of teenagers who experience concussion will develop MS, as not all carry genetic susceptibility for the disease. However, MS is only one of several good reasons that young people should avoid repeated CNS trauma.”
The paper was published in the Annals of Neurology.