Executive Function and IQ Predict Mathematical and Attention Problems in Very Preterm Children

Oosterlaan J (2013) Executive Function and IQ Predict Mathematical and Attention Problems in Very Preterm Children. PLoS ONE 8(2): e55994. doi:10.1371/journal.pone.0055994 Executive Function and IQ Predict Mathematical and Attention Problems in Very Preterm Children Cornelieke Sandrine Hanan Aarnoudse-Moens 0 Nynke Weisglas-Kuperus 0 Hugo Joseph Duivenvoorden 0 Johannes Bernard van Goudoever 0 Jaap Oosterlaan 0 Antonio Verdejo Garca, University of Granada, Spain 0 1 Department of Paediatrics, Erasmus University Medical Centre , Rotterdam , The Netherlands , 2 Department of Paediatrics, Amsterdam Medical Centre , Amsterdam , The Netherlands , 3 Department of Paediatrics, VU University Medical Centre , Amsterdam , The Netherlands , 4 Department of Clinical Neuropsychology, VU University Amsterdam , Amsterdam , The Netherlands Objective of this study was to examine the impact of executive function (EF) on mathematical and attention problems in very preterm (gestational age # 30 weeks) children. Participants were 200 very preterm (mean age 8.2 6 2.5 years) and 230 term children (mean age 8.3 6 2.3 years) without severe disabilities, born between 1996 and 2004. EFs assessed included verbal fluency, verbal working memory, visuospatial span, planning, and impulse control. Mathematics was assessed with the Dutch Pupil Monitoring System and parents and teachers rated attention problems using standardized behavior questionnaires. The impact of EF was calculated over and above processing speed indices and IQ. Interactions with group (very preterm versus term birth status) were examined. Analyses were conducted separately for two subsamples: children in preschool and children in primary school. Very preterm children performed poorer on tests for mathematics and had more parent and teacher rated attention problems than term controls (s..11, Ps,.01). IQ contributed unique variance to mathematics in preschool and in primary school (s..16, Ps,.007). A significant interaction of group with IQ ( = 2. 24, P = .02) showed that IQ contributed unique variance to attention problems as rated by teachers, but that effects were stronger for very preterm than for term infants. Over and above IQ, EF contributed unique variance to mathematics in primary school ( = .13, P,.001), to parent rated inattention in preschool and in primary school (s.2.16, Ps,.04), and to teacher rated inattention in primary school ( = 2.19; = .19, Ps,.009). In conclusion, impaired EF is, over and above impaired IQ, an important predictor for poor mathematics and attention problems following very preterm birth. - Most very preterm (gestational age # 30 weeks) infants survive without major disabilities.[1] However, a majority of these nondisabled survivors suffer from academic and behavior problems that persist into adulthood.[2] About 70% of this population has special educational needs, and the social and economic burden is large. The most pronounced academic and behavior problems are poor mathematics and attention problems.[3,4] We have recently shown that preschool mathematical abilities comprising numerical reasoning skills are already substantially impaired in very preterm children.[5] To enable early intervention, more insight in mechanisms involved in these mathematical and attentional problems is needed. A large body of literature on term children has demonstrated that higher-order neurocognitive processes, the so-called executive functions (EF) are crucial in explaining academic difficulties and behavior problems.[613] EF are prefrontal brain functions that control thought and behavior. Typical lists of EF include the capacity to mentally manipulate information in mind (i.e. working memory), generating as many different solutions for a particular problem as possible (i.e. fluency), developing strategies to reach a future goal (i.e. planning), and inhibiting responses to irrelevant stimuli (i.e. impulse control).[10,14,15] Research has consistently described that very preterm birth affects EF.[3,1618] Nevertheless, studies linking impaired EF to academic achievement and behavioral difficulties in this population remain scarce.[1923] The few available studies have shown that very preterm childrens poor impulse control and working memory skills are related to academic underperformance and inattentive behavior. Some studies, however, have suggested that slow processing speed underlies this relationship.[20,22] Slowed processing speed results from white matter abnormalities,[24] a phenomenon frequently observed in very preterm children.[25 27] Compromised white matter may as well result in inconsistent speed, [28] with major trial-to-trial variations in performance. Such variations have been postulated as the specific deficiency in Attention Deficit Hyperactivity Disorder.[2931] and may as well characterize attention problems in the very preterm population.[32] Given the ongoing debate on whether IQ and EF are related or distinct concepts,[3335] earlier studies have compared the impact of impaired EF on poor academic and behavioral outcomes in very preterm children to that of impaired IQ.[23] However, poor performance on IQ tests might be caused by impaired executive processes[33], and assessment of IQ may not fully capture the range of impaired neurocognitive skills underlying poor academic and behavioral outcomes in very preterm children.[36] Aim of this study was to capture the unique contribution of EF to mathematical and attention problems in very preterm children over and above that of processing speed indices and IQ. EFs were selected on which our very preterm sample had deficits [..3 standardized mean difference [SMD]) compared to term control children.[18] Analyses were performed on a large sample of very preterm and term control children aged 4 to 12 years who were either in preschool or in primary school. Very preterm and term children were comparable in age and sex and free of severe disabilities. Participants The sample of 200 very preterm (gestational age # 30 weeks) children was derived from all (n = 1260) very preterm infants admitted between 19962004 to the neonatal intensive care unit (NICU) of the Erasmus University Medical Centre, Sophia Childrens Hospital Rotterdam, The Netherlands. 252 infants died. Twins (n = 302) were excluded as inclusion of these children would violate the assumption of independence of data. Very preterm children with severe disabilities not being able to perform tests as employed in the present study were also excluded (n = 77). Such severe disabilities were classified according to Wood et al,[37] which defined a severe disability as one that was likely to put the child in need of physical assistance to perform daily activities.[37] These children were excluded on the basis of their medical records. Remaining children were traced and if possible invited to participate (n = 270). Parents of 70 children were not willing to participate. There were no significant d (...truncated)