Objective: Several studies have shown that stressful life events are associated with a subsequent significant increase in risk of multiple sclerosis (MS) exacerbations. We wanted to study prospectively whether stress can increase the risk of developing the disease itself.
Methods: We studied 2 cohorts of female nurses: the Nurses' Health Study (NHS) (n = 121,700) followed from 1976 and the Nurses' Health Study II (NHS II) (n = 116,671) followed from 1989. The risk of MS after self-report on general stress at home and at work in the NHS in 1982 was studied prospectively using Cox regression. Logistic regression was used to retrospectively estimate the effects of physical and sexual abuse in childhood and adolescence collected in the NHS II 2001. We identified 77 cases of MS in the NHS by 2005 and 292 in the NHS II by 2004. All analyses were adjusted for age, ethnicity, latitude of birth, body mass index at age 18, and smoking.
Results: We found no increased risk of MS associated with severe stress at home in the NHS (hazard ratio 0.85 [95% confidence interval (CI)] 0.32-2.26). No significantly increased risk of MS was found among those who reported severe physical abuse during childhood (odds ratio [OR] 0.68, 95% CI 0.41-1.14) or adolescence (OR 0.77, 95% CI 0.46-1.28) or those having been repeatedly forced into sexual activity in childhood (OR 1.47, 95% CI 0.87-2.48) or adolescence (OR 1.21, 95% CI 0.68-2.17).
Conclusions: 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.