Abstract

Background: Adolescence is a critical period of brain structural reorganisation and maturation of cognitive abilities. This relatively late developmental reorganisation may be altered in individuals who were born preterm.

Methods: We carried out longitudinal neuropsychological testing in 94 very preterm individuals (VPT; before 33 weeks’ gestation) and 44 Term-born individuals at mean ages of 15.3 years (adolescence) and 19.5 years (young adulthood).

Results: Full-scale, verbal and performance IQ and phonological verbal fluency were significantly lower in the VPT group than the Term group at both ages. Repeated-measures ANOVA showed only one group by timepoint interaction, for semantic verbal fluency (F=10.25; df=107; p=0.002). Paired-sample t-tests showed that semantic verbal fluency increased significantly in the Term group over adolescence (t=-5.10; df=42; p<0.001), but did not increase in the VPT group (t=0.141; df=69; p=0.889). For verbal IQ, there was a significant interaction between timepoint and sex (F=4.48; df=1; p=0.036), with paired-sample t-tests showing that verbal IQ decreased in males between adolescence and adulthood (t=3.35; df=71; p=0.001), but did not change significantly in females (t=0.20; df=52; p=0.845)

Conclusion: Decrements of intellectual functioning in VPT individuals persist into adulthood. Additionally, there is a deficit in the adolescent maturation of semantic verbal fluency in individuals born VPT.