Depressive symptoms were associated with a doubling of the risk of Crohn’s disease in two large prospective cohorts of women, Dr. Ashwin N. Ananthakrishnan and his colleagues reported in the January issue of Clinical Gastroenterology and Hepatology (2013;11:57-62).
For women with recent and past episodes of depressive symptoms, the associations with the development of Crohn’s disease were significant, and were stronger for those with recent depression. The effect sizes were "in the same range we found for current smoking, oral contraceptive use, and NSAID use," all of which are known risk factors for Crohn’s disease, said Dr. Ananthakrishnan of Massachusetts General Hospital and Harvard Medical School, both in Boston, and his associates.
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"Our findings support the potential importance of a biopsychosocial model in the pathogenesis of Crohn’s disease, and suggest the need for further studies on the effect of depression and stress on immune function and regulation," they noted.
Depression and life stress long have been thought to contribute to immune dysfunction and to influence both the risk for and the course of immune-mediated disorders such as Crohn’s. But until now, few studies have examined the role of mood in the onset of Crohn’s disease and ulcerative colitis, and those that did so were retrospective, failed to adjust for possible confounders, and assessed only the occurrence of major life stressors rather than the presence of depressive symptoms.
To address these shortcomings, the investigators examined the link between depressive symptoms and later onset of Crohn’s disease and ulcerative colitis using data from the prospective Nurses Health Study I and II. NHS I enrolled 121,700 female registered nurses who were 30-55 years old at baseline in 1976, and NHS II enrolled 116,686 female RNs aged 25-42 years at baseline in 1989.
For this study, Dr. Ananthakrishnan and his colleagues analyzed data for 152,461 of these participants in the two NHS cohorts. A total of 170 developed incident Crohn’s disease and 203 developed incident ulcerative colitis during follow-up.
Depressive symptoms were assessed several times in both the NHS I and II subjects using the five-question Mental Health Index (MHI-5), a subscale of the Short Form 36 health status survey. The participants received scores ranging from 1 to 100; 16,986 women (11% of the study population) received scores of 0-52, indicating the presence of depressive symptoms.
Subjects who scored from 86 to 100 composed the reference group.
The data were adjusted to account for numerous covariates that might influence risk for Crohn’s disease and ulcerative colitis, including the subjects’ race/ethnicity; smoking status; weight; menopausal status; and use of oral contraceptives, hormone therapy, and aspirin or NSAIDs.
There was a significant and linear increase in the risk of developing Crohn’s disease as MHI-5 scores decreased. Compared with the reference group, women with an MHI-5 score of 76-85 had a hazard ratio for Crohn’s disease of 1.38, those with an MHI-5 score of 53-75 had an HR of 1.59, and women with depressive symptoms and a score of 0-52 had an HR of 2.36.
No such association was seen between depressive symptoms and ulcerative colitis.
To account for the possibility that the study subjects’ depressed mood might be due to as-yet undiagnosed GI symptoms, the researchers performed a "lag" analysis excluding all cases of Crohn’s and ulcerative colitis that developed within 2 years of MHI-5 assessment. The results were unchanged in this analysis, they said.
The investigators also performed a sensitivity analysis restricted only to cases of Crohn’s disease that developed after 1996, when the NHS subjects first were routinely questioned about their use of antidepressant medications. Adjusting for the use of these drugs only slightly attenuated the strong association between depressive symptoms and Crohn’s disease.
"Preliminary animal and human studies suggest that treating depression through administration of antidepressants, or through improvement in coping mechanisms, could reduce risk of disease relapse. Whether similar interventions can also influence risk of disease onset, particularly among individuals with genetic susceptibility for Crohn’s disease or ulcerative colitis, merits further study," Dr. Ananthakrishnan and his associates said.
This study was supported by the American Gastroenterological Association, the Crohn’s and Colitis Foundation of America, the Broad Foundation, and the National Institutes of Health. Dr. Ananthakrishnan reported no potential financial conflicts of interest; his associates reported ties to Policy Analysis, Bayer HealthCare, Millennium Pharmaceuticals, and Pfizer.