Cross-sectional associations of asthma, hay fever, and other allergies with major depression and low-back pain among adults aged 20-39 years in the United States.

Although low-back pain and depression are common comorbidities, the mechanisms responsible for their association remain unclear. The effects of proinflammatory cytokines on the hypothalamic-pituitary-adrenal (HPA) axis lead to the hypothesis that allergic reactions, as markers for inflammation-associated activation of the HPA axis, result in aberrant responses to subsequent stressors. Data from 6,836 US adults 20-39 years old from the Third National Health and Nutrition Examination Survey (1988-1994) were used. Subjects responded to questions regarding low-back pain in the past 12 months and history of asthma, hay fever, and other allergies. The history and onset of major depression were obtained from the Diagnostic Interview Schedule. Logistic regression modeling was used to estimate the associations between allergies and depression and low-back pain. Subjects with a history of any allergy were more likely to report low-back pain (odds ratio = 1.51; 95% confidence interval: 1.16, 1.96), to be diagnosed with major depression (odds ratio = 1.58; 95% confidence interval: 1.13, 2.21), and much more likely to have both major depression and low-back pain (odds ratio = 3.03; 95% confidence interval: 1.32, 6.92). Hypersensitivity reactions may prime the HPA axis to respond aberrantly to stressors, resulting in physical and behavioral consequences.