Abstract:
Introduction: Allergic diseases are prevalent in childhood and represent a substantial public health burden. While the "atopic march" describes a traditional progression from eczema to airway allergies, emerging evidence suggests multiple distinct developmental trajectories. Given the overlap between critical windows for allergy development and early brain maturation, allergic diseases may exert lasting effects on neurobehavioral health. This study aims to characterize longitudinal allergic trajectories from infancy to school age and examine their associations with behavioral outcomes.
Methods: Data were obtained from the Shanghai Birth Cohort (SBC), including 1,289 children with complete allergic data at ages 1, 4, and 7 years. Allergic conditions (eczema, allergic rhinitis, and wheeze/asthma) were defined using parent-reported ISAAC-based questionnaires and physician diagnoses. At age 4, IgE concentrations and Absolute Eosinophil Counts (AEC) were measured. Latent Class Analysis (LCA) was applied to identify developmental phenotypes. At age 7, behavioral problems were assessed using the Strengths and Difficulties Questionnaire (SDQ).
Results: LCA identified four distinct allergic trajectories:
- "Minimal allergic conditions" (70.5%, reference);
- "Early transient eczema and later rhinitis" (20.9%);
- "Early transient eczema and early-onset rhinitis" (6.7%); and
- "Persistent eczema and later rhinitis" (1.8%). Compared to the reference group, the "early-onset rhinitis" and "persistent eczema" trajectories were strongly associated with higher AEC and IgE levels at age 4.
Regarding behavioral outcomes at age 7, children in the "early transient eczema and early-onset rhinitis" trajectory demonstrated the most pronounced difficulties, with significantly higher scores for emotional symptoms (β=0.63, 95% CI: 0.09–1.17), hyperactivity/inattention (β=0.77, 95% CI: 0.10–1.44), and total difficulties (β=1.51, 95% CI: 0.13–2.89). Categorical analysis revealed that this group had a three-fold increased risk of high total SDQ difficulties (OR=3.13, 95% CI: 1.03–9.47). The "early transient eczema and later rhinitis" group showed an increased risk of high externalizing difficulties (OR=2.44, 95% CI: 1.06–5.63), while the "persistent eczema" group showed no significant behavioral associations. No significant sex-based interactions were observed.
Conclusion: Early-onset allergic transitions, particularly those involving early rhinitis, are associated with increased systemic inflammation and significant behavioral challenges by school age. These findings highlight the importance of early monitoring of allergic trajectories to identify children at risk for neurobehavioral difficulties.
