Psychological stress as risk factor for exacerbations in multiple sclerosis.

We prospectively evaluated the relationship between a common psychological stressor and relapses in multiple sclerosis (MS) in a group of 32 MS patients exposed to the threat of missile attacks during the Persian Gulf War of 1991. The number of relapses during the war and the following 2 months was significantly lower than expected based on the frequency during the preceding 2 years, suggesting that not all stress conditions increase the risk of exacerbations in MS.