Links between pediatric and adult asthma.

Connections between events occurring in early life with adult asthma suggest that both the altered regulation of airway caliber and tone and the changes in airway structure present in many asthma cases may have their roots in developmental patterns established during infancy and childhood. The Melbourne epidemiologic study, the British 1958 birth cohort, and the Tasmanian asthma survey all provide important information on the outcomes of childhood asthma in later life. Among the findings, these studies showed that in a large proportion of asthmatic children, asthma remits in early adulthood, and the severity of asthma tracks significantly with age. Newer longitudinal studies have measured lung function shortly after birth, before any respiratory symptoms have occurred. Several lines of evidence suggest that those children who will go on to have more severe and persistent asthma symptoms already have immune responses skewed toward the T-helper type 2 (TH2) at the time of the very first episodes of airway obstruction in infancy. In most children whose asthma is triggered mainly by respiratory infections, asthma symptoms appear to remit by the adolescent years. Congenital and acquired deficits in lung function, however, may lead to recurrence of these symptoms during adult life and after long periods of remission, especially among active smokers.