An interview with Prof. Scott Montgomery on ‘Hospital-diagnosed infections before age 20 and risk of a subsequent multiple sclerosis diagnosis’

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Could you tell us a bit more about who you are, where you work, and what you're currently working on, please?

My name is Professor Scott Montgomery. I work at Örebro University at Örebro University Hospital in Sweden. I'm a clinical epidemiologist and my main area of research is on the causes, consequences, and treatment of multiple sclerosis.

Could you tell us a bit more about your paper and why this topic is so important?

Multiple Sclerosis (MS) is not completely understood in terms of its causes. Infection by some agents such as Epstein-Barr Virus (EBV), has been suspected as a risk for MS. In this study, we examined whether other infections could also be implicated in the etiology of MS. To do this, we followed around two and a half million people in Sweden to examine if serious infections at different ages are associated with subsequent MS. You need to take a longitudinal approach with a relatively long follow-up because there appears to be a long interval between a disease triggering event and a diagnosis of MS as the disease develops slowly over a number of years.

What we found was that serious infections, meaning they needed hospital treatment between ages 11 and 20 years, were associated with raised MS risk in the 20s, 30s, 40s, and subsequent years. Interestingly, infections in earlier childhood, and infections before age 11, were not associated with increased risk, and this is probably due to age-related changes in the immune and nervous systems. What we found was that a variety of bacterial and viral infections in adolescence were associated with MS risk. Not all infections are a risk probably because some of them don't cause inflammation in the central nervous system that we think triggers the autoimmune process that destroys myelin and thus damages nerves in the brain and spinal cord. We saw a particularly high magnitude association for infections directly of the central nervous system, of the brain, meningitis, and encephalitis, while infections not associated with MS were things like skin infections, probably because they didn't result in inflammation in the brain. Respiratory infections, and infections of the lungs, were also associated with increased risk. This may be because T cells can be licensed and programmed in the lungs to cross the blood-brain barrier and create a pro-inflammatory environment in the brain, thus possibly triggering the autoimmunity that ultimately leads to an MS diagnosis.

It was interesting that infections in adolescents were associated with MS which was often diagnosed more than 15 years later. This helps us to better understand the sorts of exposures that are risk factors for MS and the long duration between exposure and diagnosis. Does this help with prevention? Possibly ensuring treatment of inflammation in the CNS during the acute phase of the infection could reduce some of the severe securely and could be beneficial for multiple outcomes, including reducing MS risk. Protection from severe infection is important for many reasons. This can be achieved through ways such as immunization programs, which will prevent the acute disease and delayed consequences such as MS.

What's the connection between your research and medical practice? How do you hope that your work will have an impact on therapies or treatments in the future?

There is a long prodromal phase in MS. There is disease activity, but MS isn't diagnosed, and it's difficult to treat. Understanding things that can trigger the disease at this early phase, may assist with diagnosis and treatment at an earlier time. Importantly, we've provided yet another reason to prevent serious infections in adolescence. I think this is the existing part public health message, but we can consider extending some vaccination programs.

Where could your work lead you next and what's the dream outcome here for you?

What we hope to do is identify some more specific patterns of infection, possibly related to severity, duration, and other characteristics to better identify MS risk. What is the most likely pattern that will lead to MS? We're also thinking about vaccination strategies and how they can be modified to protect from some diseases in adolescence with the additional benefit of reducing MS risk.

You can read and discover Prof. Scott Montgomery’s research here.

Hospital-diagnosed infections before age 20 and risk of a subsequent multiple sclerosis diagnosis is published in Oxford Academic

Photo Credits: The Conversation

Disclaimer: This is a transcript of a video conversation. You can listen to the recording on Researcher.