Multiple sclerosis: what is it and why does it affect women more?

But even several years before intense symptoms appear, the nervous system may already be in danger, says Riley Bove, a neurologist at the University of California (USA). “(The symptoms) don’t reach the threshold of someone going to the emergency room,” he says, but things can get ugly. There is no definitive test for multiple sclerosis. The disease is diagnosed based on a clinical history and a brain scan, which reveals multiple lesions in different areas that formed at different times.

Multiple sclerosis affects each person differently. “If you’ve met one person with multiple sclerosis, then you’ve (only) met one person with multiple sclerosis,” explains Lee Charvet, who leads multiple sclerosis research at New York University. Symptoms can vary greatly and many aspects of the disease are still unknown. However, research is beginning to clarify the origins of the disease and possible treatments.

MS is usually classified as relapsing/remitting, when symptoms disappear and return, or progressive, when symptoms get progressively worse. But Beauvais says this is a false dichotomy. “Everyone experiences worsening symptoms because everyone gets older,” he says. As we age, our body loses muscle mass and strength. In addition, patients with multiple sclerosis experience accelerated aging, which compounds these losses, Beauvais said. Rather than focusing on the dichotomy between relapsing and progressive, he says it’s more important to know whether MS is active, meaning whether new lesions are causing active symptoms.

These symptoms may include numbness, slurred speech, vision problems and loss of coordination, but others are less noticeable. So-called invisible symptoms, such as fatigue and bladder dysfunction, are more common and difficult to treat, Charvet says. Because these symptoms are harder to notice for those who don’t have MS, “it’s hard to get support and empathy,” Beauvais says.

Depression like the one described by Applegate is common in multiple sclerosis, and about half of patients experience it at some point after diagnosis. Depression may be a reaction to news of the disease, but there are also indications that other factors, such as brain damage, play a role, said Maria Gaitan, acting director of the neuroimmunology clinic at the National Institute of Neurological Disorders and Stroke. . from Bethesda (USA).

There is no exact cause of multiple sclerosis, but there is one important clue: the Epstein-Barr virus, known as EBV. In a study of more than 10 million adults, the risk of developing multiple sclerosis increased more than 30-fold after EBV infection, researchers reported in the journal Science in 2022.

If you’re reading this, chances are you’re already infected with EBV. The virus spreads through saliva, and “virtually everyone has EBV,” says Alberto Ascherio, an epidemiologist at the Harvard T.H. School of Public Health. T.Ch. Chan in the USA and author of the study. But this is not necessarily a cause for concern. The virus itself can be asymptomatic and remain latent, and since about 90 percent of adults worldwide have had EBV infection, the likelihood of developing multiple sclerosis remains about the same as the global average.

Ascherio compares the link between the virus and multiple sclerosis to the link between smoking and cancer. “Smoking causes lung cancer, but most smokers never get it,” he says. Thus, EBV can cause multiple sclerosis, but most people infected with EBV will not develop the disease. EBV may not be the definitive cause of multiple sclerosis, but it is a prime suspect at the moment.

Besides EBV infections, there are other factors that can increase the risk of multiple sclerosis. Women are about three times more likely to develop multiple sclerosis, and scientists don’t know why. One theory is that women are more susceptible to autoimmune problems because of how sensitive their immune systems have to be to tolerate foreign fetal DNA, Bove says. Sex chromosomes may also be linked, but the answer is “certainly not as simple as ‘estrogen is good or bad,'” he says.

Blood relatives of people with multiple sclerosis are also more likely to develop the disease. This does not mean that multiple sclerosis is hereditary, but the genetic variants associated with it may be. Smoking, obesity and vitamin D deficiency are also associated with multiple sclerosis. Although multiple sclerosis can be diagnosed at any age, it most often occurs in people in their 20s, 30s, and 40s.

It was previously thought that multiple sclerosis predominantly affects white women. Only in the last 10 to 15 years has the paradigm begun to shift to reflect what scientists believe to be true: The disease occurs in all racial groups, Beauvais says. Because of this persistent stereotype about multiple sclerosis, “many people of different genders, races, and ethnicities are unaware of multiple sclerosis in their communities, and this can be a barrier to getting help,” she says. Although some areas of the world have relatively few cases of multiple sclerosis, such as sub-Saharan Africa, this may be due to a shortage of neurologists rather than a lack of multiple sclerosis, Beauvais says.

There is no known cure or way to guarantee that you will not develop multiple sclerosis. For now, limiting risks by not smoking, eating a healthy diet and getting enough vitamin D are the best preventative measures, but they are not foolproof, Gaitan said.

The researchers identified markers of neuroinflammation in the blood, and in the future, testing these markers could help diagnose multiple sclerosis or detect upcoming flare-ups, allowing patients to take medications before symptoms appear.

Currently, medications can treat symptoms and prevent new injuries, but none of them reverse previous damage to the nervous system. “This is the next big thing on the horizon,” Charvet says.

There is nothing known that can completely prevent multiple sclerosis, but raising awareness is an important step in early detection of the disease. “You need to be aware of this disease and know that if it is diagnosed and treated early, the progression of the disease will change,” Gaitan says.