- Multiple sclerosis triggers may occur years before symptom onset and diagnosis.
- Serious infections in people’s teenage years may increase their risk of an MS diagnosis later in life.
- Infection plays a significant role regardless of genetic risk.
Multiple sclerosis (MS) is an unpredictable disease of the central nervous system (CNS) that affects the brain and spinal cord. According to the National Multiple Sclerosis Society, there were almost 1 million adults living with MS in the United States in 2017, which is more than twice the reported number in 1975.
The initial symptoms of MS are often vision-related — such as double vision, blurred vision, red-green color distortion — but the disease can affect almost any part of the body, depending on which parts of the CNS are damaged.
In addition to issues with vision, common symptoms include problems with:
- balance and muscle weakness
- memory and thinking
- sensations of numbness, prickling, or “pins and needles”
There is currently no cure for MS, but several different treatments and therapies exist to manage the symptoms and reduce how often the symptoms return.
Scientists believe that it is an autoimmune disease. In people with MS, the immune system mistakenly attacks the myelin coating of the CNS.
Myelin protects the nerves and helps messages travel between the brain and the rest of the body. When the protective coating becomes damaged, it can slow, alter, or stop these messages.
The health record data for several million people born in Sweden between 1970 and 1994 suggest that a number of serious infections in adolescence may be risk factors for MS diagnosis in later years.
The research, which features in
Glandular fever, which occurs due to the
The study also found an increased risk associated with other types of infection and
The lead author of the study is Prof. Scott Montgomery, clinical epidemiologist and director of the Clinical Epidemiology group at Örebro University and Örebro University hospital in Sweden. He told MNT that one of the main problems with researching risk factors of the disease is that they “may occur many years before MS is diagnosed, as the disease has an extended period of development before it is sufficiently symptomatic for a diagnosis.”
A second study, which appears in
For this study, which involved nearly 2.5 million people in Sweden, the researchers looked at data on hospital-diagnosed IM in children aged up to 10 years and adolescents aged 11–19 years. They then compared this information against MS diagnoses later in life. To understand the impact of family life — an environmental factor — and genetics, the team included siblings in the study.
Prof. Montgomery explains, “If one sibling develops glandular fever and goes on to develop MS, while the other does not develop glandular fever and does not develop MS, that would suggest that it is the glandular fever rather than any genetic predisposition that led to the MS.”
During the study period, 5,867 people received a diagnosis of MS from the age of 20 years. Overall, children and teenagers with hospital-diagnosed IM had a higher risk, but teenagers showed the greatest risk of subsequent MS diagnosis.
According to Prof. Montgomery, the take-home message of the study is that “infectious mononucleosis during ages 11–15 years was often associated with an MS diagnosis over age 30 years […]. The realization that adolescence is such an important time of susceptibility also focuses our work.”
Dr. Coetzee told MNT:
“Understanding the risk factors and triggers for MS is of vital importance to the MS community. These studies highlight the importance of carefully exploring whether viral infections like EBV and other glandular fevers put someone at greater risk for developing MS.”
He explained, “We need studies like this one to pinpoint the factors that contribute to the risk of MS so that we can develop strategies to prevent the onset of MS.”
The study was limited by the exclusion of IM diagnosis in primary care and outpatient settings, meaning that it included only the most severe infections. Similarly, the authors noted that it was not possible to identify the symptomatic onset of MS before its diagnosis.
In response to a question about the next steps for the research, Prof. Montgomery said, “We now recognize that adolescence appears to represent a period of heightened susceptibility to exposures that may result in MS.” The research team is now “working to better characterize the environmental exposures related to MS risk […], investigating whether the various risks are additive or if some modify the outcome of others.”
The effect of severe infection on the future health of children and teenagers is of growing importance in light of the
Dr. Coetzee believes that it is too early to say. He said, “At this point, it would be premature to speculate about whether someone is at higher risk of MS […] — we don’t have enough information about the long-term effects of SARS-COV-2 infection on individuals to make conclusions about an individual’s risk of developing MS due to a SARS-COV-2 infection.”