Blow to multiple sclerosis: reveal the common disease that is behind its appearance

Multiple sclerosis is a neurodegenerative disease suffered by around 55,000 people in Spain and about three million worldwide. Despite the fact that it is a disease known for more than a century, the causes that produce it and its cure are still a mystery. However, an article was published this Thursday that may usher in a new era in the investigation of this ailment.

It is not the first time that a scientific study accuses a viral infection as the cause, but the authors of this one maintain that it is the first that gathers “Compelling Evidence” for Causation Between Epstein-Barr Virus and Multiple Sclerosis. It is possible that this virus is not familiar to us by its name, however, it is the same one that causes infectious mononucleosis, the famous kiss sickness. Once this virus is contracted, the host is a carrier for life, although it goes into a latent state and it is very rare that, when reactivated, the patient becomes ill again.

The research has been carried out by a team of researchers from the Harvard TH Chan School of Public Health and has been published this Thursday in the scientific journal Science. Alberto Ascherio, lead author of the study and professor of Epidemiology and Nutrition at Harvard Chan School, explains that linking this virus with multiple sclerosis is a very important step because “suggests that many cases of multiple sclerosis could be prevented if we stop this infection. “

A cure in the future

But, in addition, Ascherio also talks about the possibility of finding a cure for this disease by focusing on the Epstein-Barr virus. Multiple sclerosis affects the brain and spinal cord; the immune system attacks myelin, which is the sheath that protects neurons, causing inflammation and, as a consequence, nerve impulses are reduced or even stopped. As the nerves are distributed throughout the human body, the symptoms can be observed in many of its parts.

Establishing the relationship between the virus and the disease was challenging because, while multiple sclerosis is a rare disease, Epstein-Barr virus can be found in more than 90% of adults. In addition, the scientists observed that the first symptoms of multiple sclerosis occurred about 10 years after infection. So the researchers worked with a large sample of patients: more than 10 million young adults serving in the United States military.

Of all of them, 995 were diagnosed with multiple sclerosis during their years of service. Every two years, the researchers analyzed a serum sample from these patients: they determined the status of the Epstein-Barr virus with respect to the first sample taken and the relationship between this and the onset of symptoms of neurological disease. Among young people who had been infected with this virus, the risk of developing multiple sclerosis in the years of service was 32 times higher.

Waiting for sclerosis

Being infected with other viruses, however, did not affect the later development of this one at all. Only after infection with the Epstein-Barr virus an increase in the serum of neurofilament light chains was observed, a biomarker of nerve degeneration typical of multiple sclerosis. According to the study, these facts cannot be explained by other risk factors for multiple sclerosis and therefore point to this virus as the main culprit.

But why can a decade pass between infection with the virus and the first symptoms of multiple sclerosis? Ascherio points out two possible explanations: the first is that we still do not know how to detect the earliest symptoms of multiple sclerosis and that, therefore, they are going unnoticed; the second, that the delay in symptoms is due to the evolution of the relationship between the patient’s immune system and the virus —This system is stimulated every time the virus reactivates.

“There is currently no effective way to prevent or treat Epstein-Barr virus infection, but, if specific antiviral drugs or vaccines are developed for this virus, this would change“Ascherio suggests. Before this Harvard Chan School team, other groups of researchers had pointed to viral infection as the mysterious possible trigger for multiple sclerosis. The first of these was published in Brain Journal in March 2021.

Suspicions after mononucleosis

This research explained that those who had suffered an infection – mostly related to the nervous and respiratory systems – they were at increased risk of developing multiple sclerosis later in life. Seven months later, the same research team published another study in the journal JAMA Network Open and, in this, they specifically pointed to infectious mononucleosis as a precedent for the later development of multiple sclerosis.

This study investigated about 2.5 million people in Sweden, of whom 5,867 had been diagnosed with multiple sclerosis from the age of 20 – the mean age of diagnosis was 31 years. After analyzing the data, they concluded that patients with infectious mononucleosis between the ages of 11 and 19 they were more likely to develop multiple sclerosis, and the risk was even higher if the infection had occurred between the ages of 11 and 15.

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