Stress in Infancy Linked to Childhood Allergies

Elevated stress hormones in infancy appear to be linked to allergies up to the age of two, a new study finds. The study, carried out by researchers at the Karolinska Institutet in Sweden and colleagues, appears in the current issue of the Journal of Allergy and Clinical Immunology.
 
The researchers collected salivary samples from 203 six-month-old children in the morning, afternoon, and evening of a single day and analyzed the samples’ level of the stress-related hormone cortisol. Blood samples from the children were collected at six, 12, and 24 months of age and subjected to specific immunoglobulin E (IgE) analysis, which tests for allergies to particular allergens. In addition, information on allergy-related symptoms was obtained by periodic examination of the participating children.
 
The researchers found that the adjusted odds ratio for the relationship between morning cortisol level and IgE sensitization was 1.60 and for eczema it was 1.28. For the afternoon cortisol level, the odds ratio was 1.56 for IgE sensitization and 1.33 for eczema. For the evening cortisol level, the odds ratio was 1.42 for IgE sensitization and 1.37 for eczema. The evening salivary cortisol level was associated with food allergy.
 
The researchers conclude that the association they found between cortisol levels and allergies suggests that an altered hypothalamic-pituitary-adrenal axis plays a role in causing allergies.