Multiple sclerosis (MS) is a neurological disease — that is, a condition affecting the nerves and nervous system. The cause of MS is unknown, but some scientists have suggested that head trauma may be a risk factor for the condition. The theory is, sustaining a traumatic brain injury could trigger an immune response in someone’s central nervous system (CNS), which could possibly be connected to them developing MS at some point thereafter.
A 2017 Swedish study that considered some 80,000 people — with and without MS and with and without head injuries — offered convincing evidence that concussions in adolescence are associated with an increased risk of developing the condition. Further, it reported that multiple concussions increased a person’s likelihood of developing MS.
However, research exploring the topic of head injury and the risk of multiple sclerosis has been mixed overall. This article looks at the related studies, and shares where MS research stands today.
Multiple sclerosis is considered an autoimmune disease, in which the immune system mistakenly creates antibodies to attack the myelin, or protective coating, of nerve fibers in a person’s CNS. Damage to nerve cells causes inflammation and scarring, which interrupts the transmission of messages throughout the brain and spinal cord. This process results in an array of symptoms, including impaired movement (including walking), fatigue, numbness, muscle spasms, and more.
A head injury can result from an outside force hitting a person’s head. Such injuries often occur in sports or car accidents and they can vary in severity. There are several theories for how head trauma could contribute to a person developing MS.
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One theory starts with the premise that a person’s head injury could trigger an autoimmune response that impacts their blood-brain barrier. The blood-brain barrier is the border of cells that lets substances in and out of your CNS. In an autoimmune response, the immune system creates cells that mistakenly attack and damage the person’s myelin. If a head injury affects a person’s blood-brain barrier, the substances that the barrier usually blocks could enter the CNS — including myelin-attacking cells. In such a scenario, their myelin becomes damaged, and that damage is followed by inflammation, then scarring, then a faulty CNS. The result of such a hypothesized sequence? The symptoms of MS.
There are other potential mechanisms through which concussions and brain injuries could be related to the development of MS:
Several studies have explored possible connections between head trauma and MS, but those have had contradictory findings. Differences among research studies — including using varying definitions of head trauma, studying populations with different backgrounds and ages, and using assorted study methods — have made it difficult for health care professionals to make claims about a possible connection between head trauma and MS. Here’s what’s known.
In one study exploring potential associations between head trauma and MS, researchers considered a group of more than 150,000 Danish men and women less than 55 years old who had been diagnosed with concussion, brain contusion, or skull fracture and hospitalized from the injury. They focused on those who had been admitted to Danish hospitals between 1977 to 1992.
Starting from the year the person’s head injury happened and ending with 1999, the scientists determined how many of the group developed MS. The researchers then compared the rates of MS occurring in that head trauma group with people who had MS but no history of head injuries. They found there was no significant statistical difference between the two groups. The researchers thus concluded that head trauma did not have an effect on a person’s risk for developing MS.
In 2013, researchers conducted a systematic review and meta-analysis that analyzed any published study from 1950 onward that had explored associations between traumatic injuries and MS. (The pool of reviewed studies was international.) They found no significant association between traumatic injury and the development of MS.
However, the studies included in their review used varying definitions of traumatic injury, ranging from “accidents and burns” to “head trauma with concussion.” Given those inconsistencies, they couldn’t definitively suggest that head trauma and MS were unrelated, either.
Because of the contradictory results and limitations of previous studies, a meta-analysis published in 2014 explored the topic of physical trauma and the risk of MS by examining 40 individual studies.
Results showed significant associations between people who had experienced head trauma and/or other physical trauma as a child and those who had head trauma later in life with a higher risk of MS occurring in their adult years. The authors called for further research on the topic, but nonetheless, their findings point to the potential connection between head trauma in childhood — and head trauma in general — and an increased risk of developing MS.
The most recent — and most compelling — evidence on the topic is from a study published in 2017 in Annals of Neurology. Researchers identified more than 7,000 people in Sweden with MS. They then compared that group with nearly 73,000 other people in Sweden without MS. Next, they took into account — in both groups — records of head concussion or broken limbs from birth to age 10 (childhood) and from ages 11 to 20 (adolescence).
The study — the largest of published studies on the topic — found that head trauma in adolescence significantly increased a person’s risk of MS later in life. It also found that people who had had one concussion between ages 11 to 20 were 22 percent more likely to be diagnosed with MS later in life as compared to the same age range of people who had never had one. Further, it indicated having multiple concussions in adolescence might possibly double a person’s likelihood to be diagnosed with MS as an adult.
Still, conclusions based on possibilities aren’t sound ones. So while this study cannot prove head trauma in adolescence causes MS, it does indicate that further research on head trauma as a risk factor for MS is warranted. Additional studies, including those examining different populations of people, need to be conducted to further validate or invalidate the findings.
Although the results have limitations (like only drawing from people living in Sweden), the possible link is worth considering. Additional studies, including those examining different populations of people, need to be conducted to further validate these findings.
The research also highlights the issue of the potential long-term negative effects of traumatic brain injuries. Thus, making the effort to protect your head from injury — with helmets, other protective sports equipment, and more — is a very important consideration.
Multiple sclerosis is neurodegenerative that gets progressively worse over time. Although scientists don’t know the exact cause of MS, they do believe it is influenced by a combination of genetic and environmental factors.
Known common denominators for people who have MS include:
These factors work in different ways — and possibly in combination with each other — to determine the overall risk a person has of developing MS.
On MyMSTeam, the social network for people with multiple sclerosis and their loved ones, more than 179,000 members come together to ask questions, give advice, and share their stories with others who understand life with MS.
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