Among the approaches the National MS Society is taking to find the cause and cure for MS is research into triggering or risk factors that influence whether a person develops the disease. Research of populations to study disease patterns, including variations in geography, demographics, socioeconomic status, genetics, environmental risk factors, and exposure to infectious agents, is called “epidemiology.” These studies provide vital information about relationships among these factors, so that we can better understand who gets MS and why, identify and explain areas with high or low rates of the disease, and assist in planning for health care and other services.
Finding a way to prevent MS will require understanding the genes that make people susceptible to developing the disease, and also identifying the environmental triggers so that those triggers can be avoided or otherwise de-railed so that MS is prevented from developing. The Society funds epidemiology studies to identify risk or protective factors, studies of how infection(s) might trigger MS. As we learn more about susceptibility genes, studies of how the immune system and genes interact with environmental factors to cause MS become more feasible.
Epidemiologic studies have given us some important clues about who develops MS:
- The disease affects more than twice as many women as men.
- It is most common among people with a northern European heritage, but people of other backgrounds develop the disease as well.
- MS appears to be more prevalent in temperate regions of the world than in the tropics.
- It is diagnosed most often in people between the ages of 20 and 50, although it also can develop quite early or quite late in life.
- Some possible risk factors that have been identified for MS include cigarette smoking and Epstein Barr virus.
- Some possible protective factors that have been identified for MS include intake of vitamin D and greater exposure to sunlight.
Epidemiological studies ultimately seek to discover the cause of MS, and may also serve as the basis for developing future treatments. Read more about what epidemiology studies are telling us about that cause of multiple sclerosis (.pdf).
Many investigators believe that no single infectious agent or environmental factor is “the” cause of MS. Rather, they are exploring how a susceptible person’s immune system reacts to a variety of viral or other infections and environmental exposures, and how immune function is linked to hormonal and other factors.
The National MS Society is currently funding several research projects related to MS epidemiology and infectious triggers. These include:
- Anthony J. McMichael, MBBS, PhD (The Australian National University) is conducting “A case control study of past sun exposure and first demyelinating events” to investigate whether vitamin D, through sunlight exposure, reduces the risk of developing MS. Recent research indicates that UVR (or vitamin D synthesized via UVR exposure) can dampen the immune attack. This might provide a biological mechanism for reduced MS where UVR exposure is higher. The team is comparing lifetime sun exposure in two groups – people at risk for developing MS (because they experienced an initial neurological episode) and people without MS -- using advanced imaging technology to examine skin, measuring vitamin D status (produced by UVR), and administering a questionnaire about sun exposure. This study may bring us new insight into non-genetic factors that may make people susceptible to the development of MS, and may suggest new avenues for treatment or prevention.
- Researchers at the University of Utah are following up on evidence that colds caused by “picornoviruses” are associated with MS attacks, to detect specific viruses causing the colds that may be linked to MS attacks, and comparing MS attack rates in individuals whose colds are due to picornoviruses compared to other types of virus. This study may provide important clues to the specific viral triggers of some MS attacks, and new leads for preventing or treating those attacks.
- Ilya Kister, MD (New York University) is conducting a pilot project on the “Prevalence and significance of migraines and other headaches in MS.” Headaches are a common, yet understudied problem among people with MS. Why do headaches seem to be more frequent in MS than among healthy people? Many answers are possible. Dr. Kister’s team is carrying out a large-scale study with the aim of characterizing the types of headaches that people with MS experience, estimating how frequently they occur, and comparing symptoms and MRI features in people with MS with and without headaches. The team hopes to better understand headaches in MS and pinpoint effective strategies to help alleviate this troublesome symptom.
- Helen Tremlett, PhD (University of British Columbia) is asking, “Do relapses affect disease progression in MS?” by evaluating the long-term relationship between MS attacks and disability in a large group of individuals with MS. The majority of people with MS experience disabling relapses that can last weeks to months before a full or partial recovery occurs. However, the progression to permanent disability is not necessarily associated with a relapse. The team is focusing on patients enrolled in a database that holds data on 6000 people with MS in British Columbia, examining relapse rates in over 2500 people who have not taken disease-modifying drugs and have been followed for up to 23 years. They are investigating the effect of MS relapses occurring at different stages of the disease on disability progression, using measures such as the EDSS, a scale that measures disease activity. This study may provide much-needed information on the progression of MS, and on how to tailor treatments for individuals with this disease.
- Lauren Krupp, MD (State University of New York at Stony Brook) has been identifying cases and characteristics of MS in children under 18 in a region of New York, to lay the groundwork for future studies of this rare condition. Her team is attempting to identify as many children with pediatric MS who reside in Long Island, New York as possible, and to estimate its prevalence in the general population. They are also determining whether there are any demographic differences, including race, ethnicity and gender, between children with MS and children without MS. This pilot study is an important first step toward furthering our understanding of MS in children. (Read more about pediatric MS and what we’re doing about it).