NARCOMS Report-Recent Research Findings
Ruth Ann Marrie, MD, PhD-Mellen Center for MS Treatment and Research, Cleveland Clinic Foundation-CMSC/NARCOMS Research Fellow; Tuula Tyry, PhD, MAED-NARCOMS Program and Editorial Manager-Barrow Neurological Institute, Phoenix, Arizona
The Consortium of Multiple Sclerosis Centers (CMSC) started the NARCOMS project in 1993 to aid multiple sclerosis (MS) research. More than 32,000 persons have enrolled in the NARCOMS Registry since 1996, when enrollment first opened. Participants are from the United States, Canada, and over 50 other countries around the world. After ten years of work, the value of the NARCOMS project is being demonstrated with a growing number of publications and presentations. We are very pleased to share some of the more recent research findings with you.
Three NARCOMS presentations at recent national meetings focused on environmental factors (such as sunlight exposure) in MS. Previous studies suggested a seasonal pattern to MS births (James, 1995; Willer et al., 2005). These studies found a higher fraction of MS births in the late spring implying that the pregnancy was occurring over months of low sunlight exposure, and a lower fraction of births occur in early winter following pregnancies that take place over high sunlight periods (James, 1995; Willer et al., 2005). We examined season of birth among 10,247 American NARCOMS participants, born in the Northern United States. Unlike other studies, we did not find a seasonal pattern to MS births. The greatest number of births was in September (933) and the fewest were in February (746); this difference was not meaningful (Figure 1).
We did find, however, that NARCOMS participants are more likely to be born in northern latitudes than expected. About 29% of the US population was born north of 42 degrees latitude. More than 40% of NARCOMS participants were born north of 42 degrees latitude (Figure 2). This finding is consistent with previous migration studies; that is, studies of persons who move between areas with differing risks of MS. Prior studies of persons moving between the northern and southern parts of the US suggested that exposures during early life affect the risk of developing MS ( Detels et al., 1978). Factors being studied include infections, sunlight, vitamin D, and diet (Detels).
A Canadian study suggested that the ratio of women to men with MS is changing (Orton et al., 2006). We looked at the female/male ratio among NARCOMS participants according to the year of diagnosis, and the age of MS onset. The ratio of women to men with MS was two to one in 1960, but increased to about four to one by 2000. This suggests that more women than men are developing MS. Smoking was examined as a potential factor, but did not explain the changes over time. More research is needed to find out why, but changing environmental factors are suspected to play a role. Possible factors could be lifestyle factors, workplace exposures, changes in diet or weight gain, and hormone therapy.
Comorbidity and Lifestyle Factors
Three NARCOMS presentations focused on co-existing health conditions and lifestyle factors in MS. In the Fall 2006 questionnaire, more than three-quarters of participants had a co-existing health condition. The most common conditions reported were high blood pressure, high cholesterol, and arthritis. These conditions are also common in the general population.
Many participants reported that they currently smoked, or smoked in the past; 55% had ever smoked. More NARCOMS participants have ever smoked than persons of the same age in the general population (Figure 3). Several studies suggested that smoking is a risk factor for MS; our findings would be consistent with that hypothesis (Hernan, Olek, & Ascherio, 2001; Riise, Nortvedt, & Ascherio, 2003). One study suggested that smoking negatively affects disability in MS (Hernan et al., 2005). The high frequency of smoking among NARCOMS participants suggests that further research is needed about smoking and its effects on MS.
We also examined physical activity. Physical inactivity increases the risk of heart disease, obesity, osteoporosis (thinning of the bones), and other health problems. NARCOMS participants reported low levels of physical activity during leisure time. Only a quarter of participants reported moderate or heavy leisure time activity. This is similar to the activity level reported in the general US population, but is less than recommended. The Centers for Disease Control recommends thirty (30) minutes of moderate physical activity on most days of the week. A regular exercise program can decrease MS-related fatigue and improve walking ability (Mostert & Kesselring, 2002; Oken et al., 2004; Romberg et al., 2004). Participants who had low levels of activity reported more fatigue and trouble walking than participants who were more active.
Overall, these findings suggest that patients with MS often have more than one health condition. Patients may need help with quitting smoking, and finding ways to exercise despite disability and fatigue. More research is needed about co-existing health conditions and lifestyle factors in MS.
Summary and Conclusions
MS is a complex disease to understand, and there are many important questions yet to answer. NARCOMS Registry participants make an invaluable contribution to MS research. We truly appreciate your past and future contributions to the Registry.
Detels, R., Visscher B. R., Haile, R. W., Malmgren, R. M., Dudley, J. P., & Coulson, A. H. (1978). Multiple sclerosis and age a migration. American Journal of Epidemiology, 108, 386-393.
Hernan, M. A., Jick, S. S., Logroscino, G., Olek, M. J., Ascherio, A., & Jick, H. (2005). Cigarette smoking and the progression of multiple sclerosis. Brain, 128, 1461-1465.
Hernan, M. A., Olek, M. J., & Ascherio, A. (2001). Cigarette smoking and incidence of multiple sclerosis. American Journal of Epidemiology, 154, 69-74.
James, W. H. (1995). Season of birth in multiple sclerosis. Acta Neurologica Scandinavica, 92, 430.
Mostert, S., & Kesselring, J. (2002). Effects of a short-term exercise training program on aerobic fitness, fatigue, health perception and activity level of subjects with multiple sclerosis. Multiple Sclerosis, 8, 161-168.
Oken, B. S., Kishiyama, S., Zajdel, D., Bourdette, D., Carlsen, J., Haas, M., et al. (2004). Randomized controlled trial of yoga and exercise in multiple sclerosis. Neurology, 62, 2058-2064.
Orton, S. M., Herrera, B. M., Yee, I. M., Valdar, W., Ramagopalan, S. V., Sadovnick, A. D., et al. (2006). Sex ratio of multiple sclerosis in Canada: A longitudinal study. Lancet Neurology, 5, 932-936.
Riise, T., Nortvedt, M. W., & Ascherio, A. (2003). Smoking is a risk factor for multiple sclerosis. Neurology, 61, 1122-1124.
Romberg, A., Virtanen, A., Ruutiainen, J., Aunola, S., Karppi, S.L., Vaara, M., et al. (2004). Effects of a 6-month exercise program on patients with multiple sclerosis: A randomized study. Neurology, 63(11), 2034-2038.
Willer, C. J., Dyment, D. A., Sadovnick, A. D., Rothwell, P. M., Murray, T. J., & Ebers, G. C. Canadian Collaborative Study Group. (2005). Timing of birth and risk of multiple sclerosis: Population based study. British Medical Journal, 330 (7483), 120.