Objective: To test the hypothesis that effects of early diet on cognition observed at age 8 years persist in adolescents born preterm at < or = 30 weeks gestational age.
Study design: A subgroup from a preterm infant cohort recruited for a randomized trial studying the effects of early dietary intervention was assessed at age 16 years. IQ scores were compared between those assigned a high-nutrient diet (n = 49) or standard-nutrient diet (n = 46) in infancy at both 8 and 16 years.
Results: At age 8 years, the high-nutrient group had higher mean Verbal IQ (VIQ; P = .03), Performance IQ (P = .01), and Full-Scale IQ (P = .02) scores compared with the standard-nutrient group; the VIQ difference persisted at adolescence (P = .02). This effect was accounted for principally by a significant difference in the mean Verbal Comprehension Index score (P < .008).
Conclusions: A brief period of dietary intervention after preterm birth, principally between 26 and 34 weeks of gestation, affected IQ at age 16 years. A standard-nutrient diet was associated with lower VIQ, accounted for mainly by differences in verbal comprehension, which persisted after control of social factors.