Abstract
AIM: To test whether poor childhood pulmonary function explains the relationship between extremely preterm (EP) birth and attention-deficit/hyperactivity disorder (ADHD) symptoms in young adulthood. METHODS: EPICure birth cohort participants include children born <26 weeks' gestation in the United Kingdom and Ireland in 1995 and their term-born classmates. Predictor was EP birth. Outcomes were inattention/hyperactivity subscale z-scores at 19 years. Forced expiratory volume (FEV1) z-scores in childhood and young adulthood were mediators. We used recursive path analysis to determine the direct effect of EP birth on inattention/hyperactivity and its indirect effect through pulmonary function. RESULTS: Ninety EP and 47 term-born participants had pulmonary function testing at 11 and 19 years. Inattention z-scores were higher in the EP group (mean difference 0.55 [95% CI 0.11, 0.99]) but not hyperactivity. Compared to term-born peers, EP participants had lower FEV1 z-scores at 11 (mean difference-1.35 [95% CI -1.72, -0.98]) and 19 (mean difference-1.29 [95% CI -1.65, -0.92]). Path models revealed that childhood pulmonary function explained the relationship between EP birth and inattention. CONCLUSIONS: Extremely preterm young adults have increased risk for inattention compared to term-born peers. Poor pulmonary function appears to underlie this risk. The mechanisms responsible remain unclear and warrant further study.