More MS news articles for September 2002

Montreal Study Examines Lifestyle, Medical History Factors and MS

http://www.mssociety.ca/en/research/PC020913.htm

September 13, 2002
Multiple Sclerosis Society of Canada
Medical Update Memo

Summary

A research team led by University of Montreal epidemiologist Parviz Ghadirian, Ph.D., examined the role of a number of socio-demographic, lifestyle and medical history factors to determine whether they might be associated with the development of multiple sclerosis. The researchers found that the presence of a number of these factors were reported more frequently by adults with MS as compared to control subjects not having MS. These factors included cigarette smoking in the year prior to diagnosis of MS, contact with pet birds (for women), a family history of a number of common childhood diseases (e.g., mumps, measles, and rubella) and experiencing head injury. According to Dr. Christina Wolfson, Professor, Department of Epidemiology and Biostatistics, McGill University, and member, Health Research Committee of the MS Society of Canada, this research, while interesting, must be interpreted cautiously as the study did not include an investigation of the possible differences in genetic backgrounds of the two groups, and recall bias may influence some of the findings. This research, however, should be helpful in providing direction for future studies.

Details

A research team led by University of Montreal epidemiologist Parviz Ghadirian, Ph.D., examined the role of a number of socio-demographic, lifestyle and medical history factors to determine whether they might be associated with the development of multiple sclerosis. The investigators reported that people with MS were more likely to report the presence of certain factors in the one year before diagnosis or in the time before onset of symptoms than were a control group of people without MS matched by age, sex, and area of residence. (Canadian Journal of Public Health, July-August 2001). Dr. Ghadirian's research team included investigators from Behavioral Health, Louisville, Ky.; Actilab Pharma Inc., Montreal; and European Institute of Oncology, Milan, Italy.

Methodology

The researchers interviewed 197 people with MS who lived in Montreal and who were identified with the collaboration of a local MS organization or who responded to a public request for participation in the study. They were matched with controls drawn at random from the general population by age, sex and residential phone number. The study participants were interviewed by trained interviewers who administered a questionnaire that had been modified from previous research on diet and chronic diseases. At the time of the study the average age of male MS cases was 42.4 years, while the women were slightly younger at 37.7 years. The matching procedure yielded a control group of similar age.

Results

The researchers found the presence of several factors to be more likely to be reported by MS cases than their matched controls.

Several other factors that were investigated were found to be more frequently reported by the controls as compared to the MS cases suggesting a possible protective effect. Significance of the Results

According to Dr. Christina Wolfson, Professor, Department of Epidemiology and Biostatistics, McGill University, and member, Health Research Committee of the MS Society of Canada, this research, while interesting, must be interpreted cautiously as the study did not include an investigation of the possible differences in genetic backgrounds of the two groups, and recall bias may influence some of the findings. This research, however, should be helpful in providing direction for future studies.

The possible association between contact with domestic animals (dogs, cats and birds) and the development of MS has been investigated over the years with inconsistent findings. However, if verified these findings would be compatible with a prevailing theory involving the possible role of viruses in the development of MS. The finding of a possible protective effect of exposure to cats in the control group in this study is contradictory to other research findings.

The observation of an increased prevalence of family history of other diseases (mumps, measles and rubella in particular) would also fit with the theory of increased contact of MS cases with sources of viruses. It has been suggested that MS may be the result of exposure to any one of a number of common viruses or other environmental factors of a genetically susceptible individual at a time in his/her life that would make this exposure lead to MS.

In terms of the observation of an association between cigarette smoking and the development of MS, a similar observation was made in an article in the American Journal of Epidemiology ("Cigarette Smoking and Incidence of Multiple Sclerosis", July 2001) which reported results using data from the large U.S. Nurses Health Study. The authors of that study conclude that although the results from the prospective study do not prove cause-and-effect, they do suggest that smoking is associated with an increased risk of MS. Overall, added Dr. Wolfson, given the known health risks of smoking, avoiding cigarettes and other tobacco products is strongly recommended.

As with other epidemiological research, however, the findings from Dr. Ghadirian's research must be interpreted in light of the fact that after developing a disease, cases may over report exposures to any number of factors given the need to explain their disease. This type of recall bias can lead to overestimation of associations between possible environmental factors and disease.

Disclaimer

The Multiple Sclerosis Society of Canada is an independent, voluntary health agency and does not approve, endorse or recommend any specific product or therapy but provides information to assist individuals in making their own decisions.

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© 2002 Multiple Sclerosis Society of Canada