Relationships between intelligence, executive function and academic achievement in children born very preterm

Background: Children born very preterm are at higher risk of adverse neurocognitive and educational outcomes. However, how low intelligence (IQ) and low executive function may each contribute to poorer academic outcomes at school age requires clarification. Aim: To examine the associations between intelligence, executive function and academic achievement in children born very preterm. Design/methods: This cohort study assessed children born < 30 weeks' gestation or < 1500 g at age 7 years using the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) for IQ, and the Test of Everyday Attention for Children (TEA-Ch) and Behavior Rating Inventory of Executive Function (BRIEF) for executive function. Academic achievement was rated by teachers against curriculum standards. Results: Of the 76 children (35 girls, 41 boys, mean age = 7.2 year), 22 (28%) were rated below expected level for reading, 32 (42%) for writing and 38 (50%) for mathematics. After adjustment for sex and socioeconomic status, low IQ (OR's 9.0-12.3) and most low executive function measures (OR's 4.1-9.3) were associated with below-expected achievement. After further adjustment for IQ, low cognitive flexibility (OR = 9.3, 95% CI = 1.2-71.5) and teacher ratings of executive function (OR = 5.3, 95% CI = 1.4-20.2) were associated with below-expected achievement. Mediation analysis showed IQ had indirect effects on writing (b = 1.5, 95% CI = 0.6-3.1) via attentional control; and on reading (b = 1.0, 95% CI = 0.2-3.2) and writing (b = 0.8, 95% CI = 0.1-2.5) via cognitive flexibility. Conclusions: Both low IQ and low executive function are associated with below-expected teacher-rated academic achievement in children born very preterm. IQ may influence academic achievement in part through executive function.