Contrary to popular belief, stressful life events do not appear to be linked to the risk of developing MS (multiple sclerosis), researchers wrote in the journal Neurology.

According to previous studies, stressful events increase the likelihood of flare-ups in patients who already have MS.

Scientists from the USA and Norway set out to determine whether stress might raise the risk of developing MS itself, among people who do not have the disease.

They gathered data on 121,700 females nurses from the Nurses' Health Study (NHS) which started in 1976, as well as the Nurses' Health Study 2 (NHS2) involving 116,671 female nurses which started in 1989.

All the participants' self-reported their general levels of stress at work and at home.

By 2005 they had identified 77 cases of MS in the NHS, and 292 cases by 2004 in the NHS2.

They made adjustments for age, ethnic group, BMI (body mass index) at age 18, and smoking status.

The authors found no link between MS risk and home stress in the NHS. Not even among those who had reported severe physical or sexual abuse when they were children or teenagers.

The researchers concluded:

"These results do not support a major role of stress in the development of the disease, but repeated and more focused measures of stress are needed to firmly exclude stress as a potential risk factor for MS."

MS rates are lower the nearer you go to the equator, with very northern and very southern regions of the planet having the highest rates. Experts believe vitamin D intake is linked to MS risk. Migration studies have found that migrants acquire their new region's susceptibility to MS.

Approximately 250,000 to 350,000 individuals in the USA have been diagnosed with MS. It is more common in Caucasians and females. The average age of onset is between 20 and 40 years. Children whose parent has/had MS have a higher risk of developing it themselves.

"Stress and the risk of multiple sclerosis"
T. Riise, PhD, D.C. Mohr, PhD, K.L. Munger, ScD, J.W. Rich-Edwards, PhD, I. Kawachi, MD and A. Ascherio, MD
Neurology. May 31, 2011 vol. 76 no. 22 1866-1871. doi: 10.1212/WNL.0b013e31821d74c5

Written by Christian Nordqvist