Mar 04, 2009
Society Convenes Workshop on Strategies to Find Cause of MS, Factors Driving Progression, and Ways to Estimate MS Frequency
What triggers MS, and when? While most develop symptoms in adulthood, many scientists believe that people whose genes make them susceptible to MS encounter the unknown trigger years before symptoms occur, but no one knows when. Is it in the teen years? Before birth?
A recent international workshop held in New York City and convened by the National MS Society, co-chaired by epidemiologist Lorene Nelson, PhD (Stanford University) and neurologist Leslie Weiner, MD (University of Southern California), considered these and other questions to develop strategies to identify MS triggering and risk factors that cause MS (or protect against it), factors that drive MS progression and predict prognosis, and studies to determine its prevalence and incidence in the U.S.
Designing Studies for Different Purposes
“There’s a powerful smokescreen between the time a person experiences the triggering factor or factors for MS, and the years later when MS symptoms begin,” commented John Richert, MD, head of research and clinical programs at the National MS Society at the opening session of the workshop. “This smokescreen occurs in part because of the huge number of other environmental agents that people have been exposed to during the years or decades between the time of the trigger and the onset of clinical disease, and has made it difficult to trace back to the causes of MS.”
Many studies have looked back at lifestyles, infections, diets and many other factors, comparing the history of individuals who developed MS and those who did not. Often these studies rested on the accuracy of individuals’ memories, casting some doubt on their results. (For example, can you remember how many hours you played outside when you were, say, eight years old?)
For these and other reasons, prospective studies that look ahead, not backward, are better suited for documenting experiences before a person develops a disease. These prospective studies can take many years, and involve studying many people, only a fraction of whom will eventually develop a relatively rare disease like multiple sclerosis.
Some prospective studies that are already in place are playing important roles in identifying factors that may protect against MS (such as vitamin D levels/sunlight exposure) or may increase risk (such as smoking tobacco and mononucleosis/Epstein-Barr virus). Participants discussed these and also learned from investigators involved in longitudinal studies that are seeking risk factors for other diseases, including a study of sisters of women with breast cancer, an inflammatory bowel disease study on gene/environment interactions, and studies in juvenile diabetes.
Another type of study discussed would seek factors that predict or influence severity of disease progression by tracking people with early MS over the long term. Some studies already in place and collecting data include the Canadian MS twins studies; the Danish MS Registry capturing treatment and other information; and the Harvard Brigham and Women’s CLIMB study.
Ascertaining a more certain count of the incidence and prevalence of MS in the U.S. was also deemed by participants as important for answering questions about whether MS is on the rise, and for beefing up advocacy efforts with Congress. Currently, the federal Agency for Toxic Substances and Disease Registry is doing pilot studies on the feasibility of using existing healthcare and patient databases to determine prevalence of MS in different areas of the U.S.
Next Steps
Over the coming months, workshop organizers will evaluate the feedback from participants to develop strategies for going forward in each of the areas identified as most relevant. It is apparent that forging good studies will require the collaboration of investigators from many fields of expertise, including epidemiologists, biostatisticians, geneticists, infectious disease specialists and MS neurologists. “Bringing all of us here together at this workshop is a great start to those collaborations,” said participant Trond Riise, PhD (an epidemiologist from the University of Bergen, Norway, on sabbatical at Harvard School of Public Health).
In closing remarks, Dr. Nelson stated, “Over the last decade or so, we’ve made great strides identifying MS risk factors. Although some of them can’t be changed – like the set of genes a person is born with, or their sex or age – what is encouraging is that many of the risk factors identified are modifiable – such as vitamin D intake and smoking.”
Read more (PDF) about research exploring some of the risk factors that have been identified for MS in a recent article from the Research Now section of Momentum magazine.