Does pregnancy delay the onset of multiple sclerosis? Study suggests it can do so by over three years
Pregnancy could delay the onset of multiple sclerosis, a potentially disabling disease of the brain and spinal cord, by more than three years, says a research team. It is estimated that over 2.5 million people worldwide have multiple sclerosis (MS), and women are three times more likely to have the disease than men. Accordingly, the study, which used a global database of more than 70,000 MS patients, has implications to both a greater understanding of the causes of MS as well as the potential for the use of hormone therapy to delay the onset of symptoms, explain Monash University researchers, who led the effort.
The team suggests that pregnancy could reduce the abnormal overactivity of the immune system that causes multiple sclerosis, potentially long-term. “At present, we don’t know exactly how pregnancy slows the development of MS, but we believe that it has to do with alterations made to a woman’s DNA. We are now seeking funding opportunities to explore this exciting possibility,” says Dr Vilija Jokubaitis from the Monash University Department of Neuroscience, Australia, who led the study.
What is multiple sclerosis?
The National Institute of Neurological Disorders and Stroke (NINDS), which is a part of the US National Institutes of Health, describes multiple sclerosis as an unpredictable disease of the central nervous system. It can range from relatively benign to somewhat disabling to devastating, as communication between the brain and other parts of the body is disrupted. “Many investigators believe MS to be an autoimmune disease -- one in which the body, through its immune system, launches a defensive attack against its own tissues. In the case of MS, it is the nerve-insulating myelin that comes under assault. Such assaults may be linked to an unknown environmental trigger, perhaps a virus,” write experts.
Currently, there is no cure for MS, but treatments can help speed recovery from attacks, modify the course of the disease, and manage symptoms. Most people experience their first symptoms of MS between the ages of 20 and 40. The initial symptom of MS is often blurred or double vision, red-green color distortion, or even blindness in one eye. “Most MS patients experience muscle weakness in their extremities and difficulty with coordination and balance. These symptoms may be severe enough to impair walking or even standing. In the worst cases, MS can produce partial or complete paralysis. Approximately half of all people with MS experience cognitive impairments such as difficulties with concentration, attention, memory, and poor judgment, but such symptoms are usually mild and are frequently overlooked,” explains NINDS.
The analysis
The report, published in JAMA Neurology, is the latest among several research studies into MS conducted using the MSBase database of over 70,000 people with the disease in 35 countries. The global initiative, which has been operating for over 20 years, is led by Professor Helmut Butzkueven from Monash University’s Department of Neuroscience. MSBase supports 56 prospective investigator-initiated studies, including multiple national and regional registries in Australia, Turkey, Iran, Egypt, Malaysia, The Netherlands, Canada, the Middle East, and North Africa.
In the current analysis, the investigators wanted to understand whether pregnancy can delay the onset of MS, which is very frequently diagnosed in women of childbearing years. The authors looked at 3,600 women attending four MS clinics in two countries (the Czech Republic, and Australia), all of whom were enrolled in MSBase. The final analysis involved 2,557 women. This multicenter cohort study collected reproductive history (duration of each pregnancy, date of delivery, length of breastfeeding) on all participants between September 1, 2016, and June 25, 2019.
The results reveal that women who have been pregnant were diagnosed with their first MS symptoms, on average, 3.3 years later, compared to women who had never been pregnant. A similar delay in MS onset was also observed in women who had carried a baby to term -- with onset delayed, on average, by 3.4 years. “This study suggests an association between previous pregnancies and childbirths and timing of clinically isolated syndrome (CIS) onset, but having more pregnancies or childbirths did not appear to be associated with a later CIS onset,” the findings state.
The authors emphasize that further studies are needed to help explain the mechanisms behind the associations between pregnancy and the onset of multiple sclerosis. “Understanding the precise biological mechanisms behind the suppression of relapses in pregnancy may elucidate pathways that are critical to understanding MS pathogenesis,” writes Dr Jennifer S Graves, Department of Neurosciences, University of California, San Diego, in an editorial published in JAMA Neurology.
According to Professor Butzkueven, who is also one of the study authors, the data published could not have come from shorter studies. “The data provides a big picture view of MS causes, like this paper, and also helps clinicians decide on the best treatment strategies to prevent long-term disability in MS. Many of our huge questions need 10 years or more to get the answers, and only long-term systematic registry datasets like MSBase, with buy-in from tens of thousands of patients, can do this,” says Professor Butzkueven.