Childhood allergy and anxiety/depression in early adulthood: A longitudinal study in the ALSPAC birth cohort.

BACKGROUND

Allergic disease and common mental disorders frequently co-occur. However, little is known about the longitudinal impact of childhood allergy on the subsequent risk of developing anxiety or depression, and the possible biological mechanisms for this.

METHODS

We performed longitudinal analyses of data from the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort. The baseline sample comprised n = 5256 children with allergy data available at age 7yrs. We used multivariable regression to test associations between childhood allergy at age 7yrs and: a) four inflammatory markers at age 9yrs; b) depression and anxiety measures between ages 10-24yrs. Allergy measures included biological markers (total serum immunoglobulin E (tIgE), number of positive skin prick tests (SPTs)), and presence of eczema, asthma and/or food allergy (mother reported). Inflammatory markers were interleukin-6 (IL-6), C-reactive protein (CRP), IL-4 and IL-13. We used structural equation modelling to test whether inflammatory markers mediated the association between tIgE and depression/anxiety.

RESULTS

tIgE and having ≥ 1 positive SPT at age 7 were associated with IL-6 levels at age 9 (adjusted β = 0.09; 95 % CI 0.06-0.13; p < 0.001 and adjusted β = 0.06; 95 % CI 0.03-0.09; p < 0.001 respectively), but not with CRP, IL-4 or IL13 levels. We found no strong evidence of an association between childhood allergy and subsequent depression/anxiety during adolescence and early adulthood. This finding was consistent across biological and mother-reported allergy measures.

CONCLUSIONS

Biological markers of childhood allergy are associated with IL-6, a key inflammatory cytokine. However, childhood allergy may not have a large long-term effect on subsequent depression/anxiety.