A study of twins born preterm : Functional lateralization, cognition, and brain volumes in twin and single-born children at early school ages

Abstract: Earlier research has found that preterm birth with low gestational age (GA) and low birth weight (BW) is associated with an increased risk of long-term effects such as atypical lateralization, cognitive deficits and smaller brain volume. Similar consequences have been found in twins. This study compares twins born preterm (n=22, Mean GA=32.1, Mean BW=1781) with GA and BW matched singletons (n=24) and singletons born full term (n=22) on functional laterality, cognition (WISC-IV) and brain volume (SyMRI) at early school ages (M=7.8 years). The result showed that twins had a higher prevalence of left-handedness than both singleton groups. The preterm (PT) singletons show less right ear preference on the Dichotic Listening test than full term (FT) singletons. It was found that the FT-group performed higher than both PT-groups on cognition. Smaller brain volumes were associated with lower performances on WISC-IV in the group of twins. Furthermore it was found that the PT-singletons had smaller Total Brain volume as well as smaller Grey Matter than FT-singletons. No differences were found between the twins and the PT-singletons on intra pair comparisons. Combined with the associations found between GA, BW and cognitive performance and brain volumes the results indicate that low GA and BW are greater risk factors for long-term effects on development than twin-ship per se.