Background: Several studies have suggested an association between IgE-mediated atopic allergies and depression, although thus far no epidemiologic evidence involving a large, unselected, general-population sample and valid methods in diagnosing atopy support this putative association.
Methods: We used the Northern Finland 1966 Birth Cohort, which was followed prospectively to age 31. Of the total cohort, 5428 individuals underwent skin tests for three of the most common allergens (i.e., cat, birch, and timothy grass) and for dust mites (Dermatophagoides pteronyssinus). Data on doctor-diagnosed lifetime depression were obtained from questionnaires.
Results: After adjusting for social class, mothers' parity, place of residence, and psychiatric morbidity, the logistic regression analysis showed that the risk of developing depression when compared with nonatopic subjects increased up to 1.8-fold in atopic women (adjusted odds ratio 1.8, 95% confidence interval [CI] 1.2-2.6) and, when compared with skin-test-negative female subjects without allergic symptoms, reached 2.7-fold increases (95% CI 1.6-4.6) in those suffering from clinically manifest atopic disorders. Corresponding associations were not found among male subjects.
Conclusions: Our results indicate that women suffering from atopic diseases may possess an elevated risk for developing depression during early adulthood. Possible background theories (i.e., genetic abnormalities in serotonin metabolism, hypothalamic-pituitary-adrenal axis dysfunction, and histamine theory) are discussed.