Abstract
Atopy (immune hypersensitivity) is a common health problem associated with high levels of morbidity and service utilisation. Current risk factors do not adequately explain the development of atopy or the increasing rates of atopic disease observed in many developed nations. Recent attention has focussed on the possible role of anxiety and depression in the development and/or maintenance of atopy. However, much of this research is weakened by use of atopy measures based on self-report and/or poorly validated measures of psychological disturbance. We addressed these limitations by examining the relation between atopic disease and anxiety and depression in a longitudinal-epidemiological sample by using objective (skin prick tests to 12 allergens) as well as subjective (self-report) measures of atopy and a standardised, interviewer administered assessment of psychiatric disorder. Groups were defined as either anxiety disordered or depressed at ages 18 and 21 and were compared to healthy (no psychiatric disorder) controls on atopy scores obtained at age 21. Study members with anxiety disorders at 18 and 21 were significantly less reactive to allergens using the skin prick tests (i.e. a smaller total wheal sum) than healthy controls. There was no significant association between atopy and depression. No gender differences were found for either group. In contrast, when the analyses were repeated using self-report measures of atopy, significantly more Study members with anxiety disorders reported eczema compared to controls. A similar, albeit weaker finding was obtained for self-reported allergy to medicines. Depressed individuals were also more likely to report allergy to medicine than controls. These findings suggest that (i) self-report measures of atopy may be exaggerated by patients with negative affect, which can lead to inflated estimates of the association between atopy and psychiatric disorder and (ii) persistently anxious individuals appear to be 'protected' against atopic disease. Potential explanatory mechanisms are considered.