This is such an excellent question and one that I have wondered about as well. And I am finding that it is a difficult question to answer.
Some months back I had asked Doctor Nitin Sethi, a neurologist, to answer some reader questions and someone had asked about both diet and stress as triggers for MS. Dr. Sethi had this to say:
"Stress and food do not play a direct role in worsening MS symptomatology. I do though advise my patients to attempt to reduce the stress in their lives and eat a balanced nutritious diet."
It seems difficult to find a study which says that stress is a direct cause of MS symptoms.
In an article entitled Stress and Multiple Sclerosis, author Julie Stachowiak has this to say about studies on stress and MS:
"In a 2006, Australian researchers conducted one of the first studies to seriously examine the relationship of stress and MS relapse. This study followed 101 people with MS for 2 years and asked about their stress levels and stressful events every three months. They found that the greater number of acute stressors that a person reported predicted relapse. They also found (not surprisingly) that people who were having a relapse reported more stress. Chronic stress and stress severity did not predict relapse, only the number of acute stressors."
But then I did find one study which actually said that stress can trigger MS symptoms.
A 2007 report from CBS news entitled, "Chronic stress can cause or exacerbate MS" states that:
"Researchers have demonstrated for the first time that inflammation brought on by stress leads to the worsening of the mouse equivalent of MS."
But we are talking about mice here and not humans so....I don't know how much merit one can base on such a study.
In my humble opinion I think stress can make any illness worse. But does it actually cause symptoms? I don't know.
I would love to know what others think about this. Great topic for discussion!