MS and stress.

Both Martha King's comments in her "Heads Up" column and the feature story "MS and Stress" in the October-November 2005 issue proclaim that there is no direct cause-and-effect link between stress and the progression or worsening of MS.

But I get a different impression reading the sole research paper cited in the article. In the British Medical Journal, the researchers concluded that, "there is a consistent association between stressful life events and subsequent exacerbations in multiple sclerosis."

In an earlier paper, the researchers commented:

"We observed a significant relationship between moderately stressful life events characterized by conflict and disrupted daily routines, and the appearance of new Gd+ lesions 4 to 8 weeks later"--Mohr, "Psychological stress and the subsequent appearance of new brain MRI lesions in MS," Neurology, July 2000.

I concede that this body of research is not definitive; and many of the studies have limitations that the article explores at great length. But the article should have reported what the researchers themselves are concluding about their work.

Dave Salvatore, New Hampshire 

Dr. David Mohr, whose article, "Association between stressful life events and exacerbation in multiple sclerosis: a meta-analysis and review," appeared in the March 19, 2004, issue of the British Medical Journal, replies:

There is a lot of support for the idea that stress and MS exacerbation are related. But the data are not definitive, and the question "Does stress cause MS exacerbation?" remains unanswered. It may be that the relationship between stress and exacerbation observed by researchers is some sort of artifact and is not real--the history of science is full of these kinds of stories. But it is also possible that there is some sort of relationship that we just do not yet understand.

Our research group is looking at how stress might be involved in MS exacerbation. My guess is that, if stress plays a role, it is only one factor that interacts with many other factors. Presenting one of our hypotheses might help clarify this. People with MS sometimes have low-level MS-related inflammation that does not break through to become a full clinical exacerbation. The body has a number of mechanisms to control this type of inflammation. One of the ways that the body controls inflammation is by producing a hormone called cortisol. Stress affects the system that produces cortisol in a way that can reduce the ability of cortisol to control inflammation. One of our hypotheses is that if stress occurs while a person is experiencing some low-level MS-related inflammation, it can decrease the body's ability to control that inflammation. In this way, stress might increase the risk of an exacerbation breaking through.

I think the question is not "Can stress cause an exacerbation," but, "Can stress be added to a long list of factors that influence the risk of having an exacerbation?" While there are no definitive answers, we are working on it.

For a more complete discussion of MS, stress, and cortisol, see Dr. Mohr's "A temporal framework for understanding the effects of stressful life events on inflammation in patients with multiple sclerosis" in the January 2006 issue of Brain, Behavior, and Immunity.

--The Editor