Increased stress not linked to multiple sclerosis

By Dr. Ananya Mandal, MDMay 31 2011

According to a new study that refutes earlier evidence, stress does not appear to increase a person's risk of developing multiple sclerosis (MS). The research is published in the May 31, 2011, print issue of Neurology, the medical journal of the American Academy of Neurology.

Study author Trond Riise, PhD, with the University of Bergen in Bergen, Norway said, “While we've known that stressful life events have been shown to increase the risk of MS episodes, we weren't certain whether these stressors could actually lead to developing the disease itself.”

For the study the team looked at two groups of women nurses from the Nurses' Health Study. The first group of 121,700 nurses between the ages of 30 and 55 were followed starting in 1976. The second group of 116,671 nurses between the ages of 25 and 42 were followed from 1989. Participants were asked to report general stress at home and at work, including physical and sexual abuse in childhood and as teenagers.

Of the first group, 77 people developed MS by 2005. In the second group 292 people developed the disease by 2004. “The risk of MS is particularly high among young women, and the difference in the number of cases is consistent with the different ages of women in the two groups at the beginning of the MS follow-up,” said Riise. The team adjusted for other factors like age, ethnicity, latitude of birth, body mass at age 18 and smoking.

Results revealed that severe stress at home did not increase the risk of developing MS. There was also no significant increased risk in developing MS among those who reported severe physical or sexual abuse during childhood or adolescence. “This rules out stress as a major risk factor for MS. Future research can now focus on repeated and more fine-tuned measures of stress,” said Riise, who conducted the research as a visiting scholar at the Harvard School of Public Health.

The study was supported by the National Institute of Neurological Disorders and Stroke.

Sharon Lynch, director of the Multiple Sclerosis Clinic at the University of Kansas Medical Center in Kansas City, says it's a good study; the catch is that “stress to one person is not stress to another.”

“Stress does have an impact on your immune system, and we all believe that the immune system is involved in MS,” but there's no direct data to suggest a strong enough link, says Karen Blitz-Shabbir, director of North Shore-Long Island Jewish Medical's MS Care Center at Glen Cove (N.Y.) Hospital. But she points to other research that suggests living closer to the equator reduces MS risk. That fits with other research suggesting Vitamin D, produced from sun exposure, may protect against MS.