Multiple sclerosis (MS), which was first described in 1868, has remained a mystery for most of its causes. Multiple sclerosis (MS) has been linked to genes. This is why it is more common for people with MS to have other family members.
My colleagues and I recently found that MS is linked to several types of infections in the teens. The study did not examine whether MS-prone people were more likely than others to develop worse infections.
This could explain why MS patients are more likely to get hospital treatment.
This explanation would mean that the infection wouldn't be a risk factor for MS. It would instead identify people more likely to develop MS. This new study published in JAMA Network Open shows glandular fever, which is one of the most common infections associated with MS risk, can be a risk factor for MS later on.
Scientists have suggested that people with MS might get more infections such as glandular fever, also known as infectious mononucleosis "mono", or "kissing diseases", because of their immune systems.
Another explanation, which our study looked into, is that MS can be triggered by infection. Families with more infections may be different from those with fewer. These differences, not the infections, may be what contributes to MS risk.
Our latest study looked at siblings from the same family to confirm that infections are a risk factor for MS. Siblings share a lot of their genetic makeup and lead similar families.
If one sibling develops glandular fever and then develops MS, it would indicate that the glandular fever is to blame.
We can be more certain if we see the same pattern in multiple families.
We examined glandular fever at different age groups, because teenage years are when MS risk is highest. This study was done on 2.5 million Swedish citizens. Only 6,000 people had MS diagnosed after the age of 20.
In an analysis where siblings were compared in every family, glandular fever was found to be associated with a significantly higher MS risk at age 20. The results were then combined.
This was done to ensure that the results were not misleading. People with MS are more likely to develop severe infections from this vulnerability. These results confirmed that MS can be triggered by glandular fever and other infections.
This new study allowed us to examine in more detail when an infection can trigger MS. Glandular fever occurring in childhood was less likely to cause MS than it was after 11 years.
MS infections were most prevalent between the ages of 11 and 15, around the time when puberty occurs. The risk drops with age, and is almost non-existent by the age of 25.
This could be explained by changes in brain function and immunity as we age.
MS is a slow-developing disease
MS can occur even though glandular fever is a common trigger for MS. It's most commonly diagnosed around puberty. Many people who contracted the disease between the ages of 11 and 15 years didn't get a diagnosis of MS until they turned 30.
Because MS causes brain damage slowly, until eventually it becomes severe enough that a person is able to get a diagnosis.
MS can be caused by glandular fever in teenage years. It can enter the brain. The immune system may attack the myelin sheath, which protects nerve cells from damage caused by glandular fever.
This is known as autoimmunity. It can cause nerve damage in the brain, which can get worse over time. Modern treatments are becoming more effective at slowing down this process.
This study supports the idea that MS can be triggered by severe glandular fever, and possibly other serious infections, in the teenage years, especially around puberty. MS is often not diagnosed until at least ten to fifteen years later.
Scott Montgomery, Honorary Professor of Epidemiology at UCL
This article was republished by The Conversation under Creative Commons. You can read the original article.