Executive function in adolescents born <1000 g or <28 weeks: a prospective cohort study

Executive functioning challenges of adolescents born extremely and very preterm

Background

Children born very preterm (VPT; <32 weeks) are at increased risk of executive functioning (EF) difficulties. But less is known about the nature and extent of these executive difficulties during late adolescence, particularly across multiple EF domains and in response to varying degrees of executive demand.

Methods

Using data from a prospective longitudinal study, this paper describes the EF profiles of 92 VPT and 68 full-term (FT) adolescents at age 17 years. Relations between gestational age (GA) and later EF performance, in addition to neonatal predictors, were examined.

Results

VPT-born adolescents performed less well than FT adolescents across the domains of working memory, planning, and cognitive flexibility, with the largest differences observed for those born <28 weeks GA (effect sizes -0.6 to -1.0 SD), and when task demands were high. The effects of GA on EF outcome were fully mediated by neonatal medical complexity (b = 0.169, t = -1.73) and term equivalent white matter abnormalities (b = 0.107, t = -3.33).

Conclusion

Findings support the need for long-term cognitive support for individuals born very preterm, particularly those exposed to high levels of medical and neurological risk, with these factors largely explaining associations between GA and EF outcome.

Twenty four-hour blood pressure and cognitive outcomes in adolescents born extremely preterm and at term

AIM

To explore the impact of blood pressure on cognitive outcomes at 18 years of age in individuals born extremely preterm (<28 weeks' gestation) and at term (≥37 weeks' gestation).

METHODS

Prospective longitudinal cohort comprising 136 young adults born extremely preterm and 120 matched term controls born in Victoria, Australia in 1991 and 1992. Using linear regression, we analysed the relationships between 24-h mean ambulatory blood pressure, systolic and diastolic hypertension with cognitive outcomes.

RESULTS

For both birth groups combined, higher 24-h mean ambulatory blood pressure and systolic hypertension were associated with similar or worse cognitive outcomes. The strongest relationships were between higher 24-h mean ambulatory blood pressure and systolic hypertension with poorer general intellect, visual learning and visual memory. We found little evidence that relationships between ambulatory blood pressure and cognitive outcomes differed by birth group.

CONCLUSION

Higher 24-h mean ambulatory blood pressure and systolic hypertension were associated with poorer cognitive outcomes in individuals born extremely preterm and at term, particularly in general intelligence and visual memory.

Combining MRI and Spectral EEG for Assessment of Neurocognitive Outcomes in Preterm Infants

INTRODUCTION

Predicting impairment in preterm children is challenging. Our aim is to explore the association between MRI at term-equivalent age (TEA) and neurocognitive outcomes in late childhood and to assess whether the addition of EEG improves prognostication.

METHODS

This prospective observational study included forty infants with gestational age 24 + 0-30 + 6. Children were monitored with multichannel EEG for 72 h after birth. Total absolute band power for the delta band on day 2 was calculated. Brain MRI was performed at TEA and scored according to the Kidokoro scoring system. At 10-12 years of age, we evaluated neurocognitive outcomes with Wechsler Intelligence Scale for Children 4th edition, Vineland adaptive behavior scales 2nd edition and Behavior Rating Inventory of Executive Function. We performed linear regression analysis to examine the association between outcomes and MRI and EEG, respectively, and multiple regression analysis to explore the combination of MRI and EEG.

RESULTS

Forty infants were included. There was a significant association between global brain abnormality score and composite outcomes of WISC and Vineland test, but not the BRIEF test. The adjusted R2 was 0.16 and 0.08, respectively. For EEG, adjusted R2 was 0.34 and 0.15, respectively. When combining MRI and EEG data, adjusted R2 changed to 0.36 for WISC and 0.16 for the Vineland test.

CONCLUSION

There was a small association between TEA MRI and neurocognitive outcomes in late childhood. Adding EEG to the model improved the explained variance. Combining EEG and MRI data did not have any additional benefit over EEG alone.

Visuospatial working memory of children and adults born very preterm and/or very low birth weight

BACKGROUND

This paper examines the visuospatial working memory (WM) performance of children and adults born very preterm (VPT) and/or very low birth weight (VLBW) relative to their full-term (FT)-born peers. Of interest was the nature and severity of observed impairments, as well associations with educational/occupational functioning at each age point.

METHODS

Participants were drawn from two prospective cohort studies: (1) a regional cohort of 110 VPT (<32 weeks' gestation and <1500 g) and 113 FT born children assessed at age 12 years; (2) a national cohort of 229 VLBW (<1500 g) and 100 FT born adults assessed at age 28 years. Visuospatial WM was assessed using a four-span/difficulty-level computerized task.

RESULTS

Both children and adults born VPT/VLBW had poorer visuospatial WM than FT controls, with their performance less accurate, slower (correct trials), and less efficient with increasing task difficulty (Cohen's d = 0.27-0.51; p < 0.05). Adults had better visuospatial WM than children, but between-group differences were highly similar across ages, before and after adjustment for confounding social background and individual factors. Poorer WM was associated with lower levels of educational and occupational/socioeconomic achievement.

CONCLUSIONS

Visuospatial WM difficulties persist into adulthood raising concerns for the longer-term cognitive and adaptive functioning of VPT survivors.

IMPACT

Both children and adults born very preterm have poorer visuospatial working memory than their term-born peers. They are less accurate, take longer to respond correctly and are less efficient, with test performance declining with increasing cognitive demand. Similar differences in visuospatial working memory are observed between VPT/VLBW and full-term individuals during both childhood and adulthood, with these differences remaining even after covariate adjustment. Individuals with poorer visuospatial working memory have lower levels of educational achievement and occupational/socioeconomic success. Visuospatial working memory difficulties persist into adulthood and appear to continue to impact everyday functioning and life-course opportunities.

Connecting to Early Intervention Services After Neonatal Intensive Care Unit Discharge in a Medicaid Sample

OBJECTIVE

To describe caregiver perspectives regarding connecting to early intervention (EI) services after neonatal intensive care unit discharge in a Medicaid sample.

METHODS

Open-ended semistructured interviews and focus groups were conducted with English- or Spanish-speaking families enrolled in Medicaid in an urban high-risk infant follow-up clinic at a safety-net center, which serves preterm and high-risk term infants. We generated salient themes using inductive-deductive thematic analysis.

RESULTS

Thirty-two participants completed the study. The infant's median (interquartile range) birth weight was 1365 (969, 2800) grams; 50% were Hispanic; 31% reported living in a neighborhood with fourth quartile economic hardship. Eighty-one percent were classified as having chronic complex disease per the Pediatric Medical Complexity Algorithm and 63% had a diagnosis of developmental delay. A conceptual model was constructed and the analysis revealed major themes describing families' challenges and ideas to facilitate connection to EI. We identified subthemes related to the person in environment: health care environment/support and socio-economic resources, parent perspectives and built environment; provider level factors such as appointment scheduling, staff limitations, and parent suggestions to improve health care and service navigation, which included improved information sharing, the importance of patient advocates, video resources, early referrals to EI facilitated by the discharging hospital and system workarounds.

CONCLUSIONS

The results from this study may provide a granular roadmap for providers to help facilitate referrals to EI services. We identified several ideas such as using advocates and providing transitional resources, including online media, that might improve the connection to EI services.

Neurobehavioral Phenotype and Dysexecutive Syndrome of Preterm Children: Comorbidity or Trigger? An Update

Premature birth is a worldwide public health priority. One in ten children is born before 37 weeks of gestational age and, in developed countries, survival rates without major neonatal morbidity are increasing. Although severe sequelae associated with these births have decreased, their neurobehavioral difficulties, often associated in multiple fields, remain stable but still widespread. These neurobehavioral difficulties hamper the normal development of academic achievements and societal integration and intensify the children's needs for rehabilitation during their preschool and academic years. Severe sequelae increase when gestational age decreases. This is even truer if the socio-cultural background is impeded by low income, education and language skills as compared with defined averages. However, moderate and/or minor neurocognitive and/or behavioral difficulties are almost identical for a moderate or a late preterm birth. Obtaining a better clinical description of neurobehavioral characteristics of those pretermly born, once they reach preschool age, is essential to detect behavioral issues as well as early specific cognitive difficulties (working memory, planning, inhibition, language expression and reception, attention and fine motor skills, etc.). Such information would provide a better understanding of the executive functions' role in brain connectivity, neurodevelopment and neuroanatomical correlation with premature encephalopathy.

Cognitive and academic outcomes of children born extremely preterm

Extremely preterm birth is associated with increased risk for a spectrum of neurodevelopmental problems. This review describes the nature of cognitive and academic outcomes of extremely preterm survivors across childhood and adolescence. Evidence across meta-analyses and large prospective birth cohorts indicate that early developmental difficulties in children born extremely preterm do not resolve with age and are not improving over time despite advancements in neonatal care. While extremely preterm birth confers increased risk of widespread cognitive difficulties, considerable heterogeneity in outcomes is evident across individuals. There is a continued need for high-quality longitudinal studies to understand the developmental progression of cognitive and academic skills following extremely preterm birth, and greater focus on understanding contributing factors that may help to explain the individual variability in cognitive and academic outcomes of extremely preterm survivors.

School-aged neurodevelopmental outcomes for children born extremely preterm

As survival rates for children born extremely preterm (EP, <28 weeks' gestation) have increased with advances in perinatal and neonatal care, their long-term functioning and quality of life assume more importance. Outcomes in early childhood provide some information, but outcomes at school-age are more informative of life-long functioning. Children born EP at school-age have substantially higher rates of intellectual impairment, poorer executive, academic and motor function, more neurodevelopmental disability, and poorer health-related quality of life than do contemporaneous term-born controls. Because the rates of adverse outcomes remain unacceptably high, and particularly since some outcomes may be deteriorating rather than improving over time, new strategies to ameliorate these problems, targeting periods before, during and after birth, and throughout the lifespan, are a priority.

Children Born Prematurely May Demonstrate Catch-Up Growth in Pre-Adolescence

Introduction Children born prematurely often score lower on standardized tests of language in early childhood. Less is known about longer term outcomes. This investigation considered language outcomes in pre-adolescent children born very preterm/very low birthweight, as assessed by both standardized test scores and language sample measures, and explored attention abilities as a possible moderating factor. Method The present investigation provided a longitudinal follow-up to Mahurin Smith et al. (2014) by examining the language outcomes of 84 children at the 11-year time point (39 with a history of prematurity and 45 born at full term) and a total of 82 at the 12-year time point (37 with a history of prematurity, 45 born at full term). Assessments included subtests of the Clinical Evaluation of Language Fundamentals- Fourth Edition, productive language measures taken from narrative tasks, and parent and examiner ratings of attention. Results Gestational age significantly predicted standardized language scores at age 11 years, but this effect was no longer statistically significant at age 12 years. When parent ratings of attention were considered as additional variables, gestational age was no longer a significant predictor. Gestational age did not serve as a significant predictor for the productive language measures at either time point. Discussion Results indicate that catch-up growth in language may take place in pre-adolescence for many children born prematurely. Clinical implications focus on the need to utilize multiple forms of language assessment and to directly consider the potential role of attention on standard test results.

Stability of Executive Functioning of Moderately-Late Preterm and Full-Term Born Children at Ages 11 and 19: The TRAILS Cohort Study

Moderately-late preterm-born children (MLPs, 32-36 weeks gestational age, GA) have poorer executive functioning (EF) at primary school age than full-term children (FTs). Evidence is lacking on their EF in adolescence, but for early preterm-born children, this has been shown to be much poorer. We, therefore, compared EF of MLPs and FTs at ages 11 and 19 and assessed development between these ages. We obtained data from TRAILS, a community-based prospective cohort study in the northern Netherlands, on 98 MLPs and 1832 FTs. We assessed EF by the Amsterdam Neuropsychological Tasks (ANT) at ages 11 and 19 years and computed gender-specific z-scores on reaction time and accuracy. We compared baseline speed, pattern search, working memory, sustained attention, inhibition, and attentional flexibility of MLPs and FTs crude, and adjusted for small-for-GA status, socioeconomic status, and estimated intelligence. MLPs and FTs performed similarly on all EF components at ages 11 and 19, except for the speed, but not the accuracy measure of attentional flexibility. This was slightly poorer for MLPs than FTs at age 19 (adjusted B 0.25; 95% confidence interval: 0.00 to 0.50; p = 0.047), but not at age 11 (adjusted B -0.02; -0.19 to 0.22; p = 0.87). Differences in EF between MLPs and FTs did not change significantly from age 11 to 19. MLPs had comparable EF on most components as FTs, with only attentional flexibility at age 19 developing slightly poorer for MLPs than for FTs. These findings suggest the effects of MLP birth on long-term EF to be small.

Prenatal maternal C-reactive protein prospectively predicts child executive functioning at ages 4-6 years

This prospective longitudinal study evaluated multiple maternal biomarkers from the preconception and prenatal periods as time-sensitive predictors of child executive functioning (EF) in 100 mother-child dyads. Maternal glycated hemoglobin (HbA1C ), C-reactive protein (CRP), and blood pressure (BP) were assayed before pregnancy and during the second and third trimesters. Subsequently, children were followed from birth and assessed for EF (i.e. cognitive flexibility, response inhibition) at ages 4-6 years. Perinatal data were also extracted from neonatal records. Higher maternal CRP, but not maternal HbA1C or BP, uniquely predicted poorer child cognitive flexibility, even with control of maternal HbA1C and BP, relevant demographic factors, and multiple prenatal/perinatal covariates (i.e. preconception maternal body mass index, maternal depression, maternal age at birth, child birth weight, child birth order, child gestational age, and child birth/neonatal complications). Predictions from maternal CRP were specific to the third trimester, and third trimester maternal CRP robustly predicted child cognitive flexibility independently of preconception and second trimester CRP. Child response inhibition was unrelated to maternal biomarkers from all time points. These findings provide novel, prospective evidence that maternal inflammation uniquely predicts child cognitive flexibility deficits, and that these associations depend on the timing of exposure before or during pregnancy.

Breastfeeding improves dynamic reorganization of functional connectivity in preterm infants: a temporal brain network study

Substantial evidences have shown the benefits of breastfeeding to infants in terms of better nutrition and neurodevelopmental outcome. However, the relationship between brain development and feeding in preterm infants, who are physiologically and developmentally immature at birth, is only beginning to be quantitatively assessed, coinciding with the recent advent of neuroimaging techniques. In the current work, we studied a sample of 50 preterm infants-born between 29 and 33 weeks (32.20 ± 0.89 weeks) of gestational age, where 30 of them were breastfed and the remaining 20 were formula-fed. Resting-state functional magnetic resonance imaging (fMRI) was recorded around term-equivalent age (40.00 ± 1.31 weeks, range 39-44 weeks) using a 1.5-T scanner under sedation condition. Temporal brain networks were estimated by the correlation of sliding time-window time courses among regions of a predefined atlas. Through our newly introduced temporal efficiency approach, we examined, for the first time, the 3D spatiotemporal architecture of the temporal brain network. We found prominent temporal small-world properties in both groups, suggesting the arrangement of dynamic functional connectivity permits effective coordination of various brain regions for efficient information transfer over time at both local and global levels. More importantly, we showed that breastfed preterm infants exhibited greater temporal global efficiency in comparison with formula-fed preterm infants. Specifically, we found localized elevation of temporal nodal properties in the right temporal gyrus and bilateral caudate. Taken together, these findings provide new evidence to support the notion that breast milk promotes early brain development and cognitive function, which may have neurobiological and public health implications for parents and pediatricians.Breastfeeding has long been recognized to have beneficial effect on early neurodevelopment in infants. However, the influence of breastfeeding on reorganization of functional connectivity in preterm infants are largely unknown. To this end, we utilized our recently developed temporal brain network analysis framework to investigate the dynamic reorganization of brain functional connectivity in preterm infants fed with breast milk. We found that beyond an optimal temporal small-world topology, breastfed preterm infants exhibited improved network efficiency at both global and regional levels in comparisons with those of formula-fed infants. Graphical abstract: Breastfeeding has long been recognized to have beneficial effect on early neurodevelopment in infants. However, the influence of breastfeeding on reorganization of brain functional connectivity in preterm infants are largely unknown. To this end, we utilized our recently developed temporal brain network analysis framework to investigate the dynamic reorganization of functional connectivity in preterm infants fed with breast milk. We found that beyond an optimal temporal small-world topology, breastfed preterm infants exhibited improved network efficiency at both global and regional levels in comparisons with those of formula-fed infants.

Social Adjustment in Adolescents Born Very Preterm: Evidence for a Cognitive Basis of Social Problems

OBJECTIVE

To increase the understanding of social adjustment and autism spectrum disorder symptoms in adolescents born very preterm by studying the role of emotion recognition and cognitive control processes in the relation between very preterm birth and social adjustment.

STUDY DESIGN

A Dutch cohort of 61 very preterm and 61 full-term adolescents aged 13 years participated. Social adjustment was rated by parents, teachers, and adolescents and autism spectrum disorder symptoms by parents. Emotion recognition was assessed with a computerized task including pictures of child faces expressing anger, fear, sadness, and happiness with varying intensity. Cognitive control was assessed using a visuospatial span, antisaccade, and sustained attention to response task. Performance measures derived from these tasks served as indicators of a latent cognitive control construct, which was tested using confirmatory factor analysis. Mediation analyses were conducted with emotion recognition and cognitive control as mediators of the relation between very preterm birth and social problems.

RESULTS

Very preterm adolescents showed more parent- and teacher-rated social problems and increased autism spectrum disorder symptomatology than controls. No difference in self-reported social problems was observed. Moreover, very preterm adolescents showed deficits in emotion recognition and cognitive control compared with full-term adolescents. The relation between very preterm birth and parent-rated social problems was significantly mediated by cognitive control but not by emotion recognition. Very preterm birth was associated with a 0.67-SD increase in parent-rated social problems through its negative effect on cognitive control.

CONCLUSIONS

The present findings provide strong evidence for a central role of impaired cognitive control in the social problems of adolescents born very preterm.

Do preschoolers with adverse birth outcomes have more distress during dental examination?

PURPOSE

Studies assessing the influence of neonatal complications on children's dental behaviour are lacking. We aimed to investigate whether prematurity, birth weight, and history of neonatal intensive care unit (NICU) hospitalisation are associated with distress during dental examination in children.

METHODS

This preliminary longitudinal, retrospective study included 42 5- and 6-year-old children. Distress during dental examination was assessed using the observational FLACC Pain Assessment Tool through video files. Children self-reported their pain (Faces Pain Scale-Revised) at the end of the session. Information about neonatal complications was obtained through medical records. Bivariate analysis was performed (P < 0.05).

RESULTS

Children with low birth weight (P = 0.047) and toothache history (P = 0.005) had higher frequency of distress during dental examination. There was no association between distress, prematurity and history of NICU hospitalisation (P > 0.05).

CONCLUSIONS

Health professionals can help to disseminate the knowledge that children with history of low birth weight are more prone to perceive distress with apparently painless procedures.

Development of executive functions from childhood to adolescence in very preterm-born individuals - A longitudinal study

Preterm-born individuals are at risk for poorer executive functions. Longitudinal studies investigating whether preterm-born individuals present persistent cognitive deficits, or a transient delay of development are scarce. We assessed developmental trajectories of executive functions (inhibition, working memory, cognitive flexibility) in 29 very preterm-born individuals (<32 weeks' gestation) and 25 term-born controls longitudinally over two time points, namely in childhood (7-12 years of age, TP1) and adolescence (13-16 years of age, TP2). Individual changes in executive functions were examined using relative difference scores (TP2 - TP1) / TP1). There was a significantly stronger improvement of inhibition (U = 477, p = .024) and cognitive flexibility (U = 312, p = .029) between childhood and adolescence in very preterm-born individuals than in term-born controls. Preterm-born individuals improved their performance in the domain of cognitive flexibility significantly more often (76%) between childhood and adolescence than controls (31%, χ² = 8.6, p = .003). Controls worsened significantly more often (36%) in the domain of inhibition than the preterm group (14%, χ² = 4.8, p = .028). Results indicate that healthy preterm-born individuals show prolonged development of executive functions throughout childhood up into adolescence.

Nurturing the preterm infant brain: leveraging neuroplasticity to improve neurobehavioral outcomes

An intrinsic feature of the developing brain is high susceptibility to environmental influence-known as plasticity. Research indicates cascading disruption to neurological development following preterm (PT) birth; yet, the interactive effects of PT birth and plasticity remain unclear. It is possible that, with regard to neuropsychological outcomes in the PT population, plasticity is a double-edged sword. On one side, high plasticity of rapidly developing neural tissue makes the PT brain more vulnerable to injury resulting from events, including inflammation, hypoxia, and ischemia. On the other side, plasticity may be a mechanism through which positive experience can normalize neurological development for PT children. Much of the available literature on PT neurological development is clinically weighted and focused on diagnostic utility for predicting long-term outcomes. Although diagnostic utility is valuable, research establishing neuroprotective factors is equally beneficial. This review will: (1) detail specific mechanisms through which plasticity is adaptive or maladaptive depending on the experience; (2) integrate research from neuroimaging, intervention, and clinical science fields in a summary of findings suggesting inherent plasticity of the PT brain as a mechanism to improve child outcomes; and (3) summarize how responsive caregiving experiences situate parents as agents of change in normalizing PT infant brain development.

What Are We Measuring as Outcome? Looking Beyond Neurodevelopmental Impairment

Outcomes of neonatal intensive care unit (NICU) graduates have been categorized by rates of neurodevelopmental impairment at 2 years old. Although useful as metrics for research, these early childhood assessments may underestimate or overestimate later functional capabilities. Often overlooked are less severe but more prevalent neurobehavioral dysfunctions seen later in childhood, and chronic health concerns that may impact the child's quality of life (QoL). Comprehensive NICU follow-up should include measures of less severe cognitive/learning delays, physical/mental well-being, and the promotion of resilience in children and families. Studies are needed to identify QoL measures that will optimize children's assessments and outcomes.

Altered functional network connectivity in preterm infants: antecedents of cognitive and motor impairments?

Very preterm infants (≤ 31 weeks gestational age) are at high risk for brain injury and delayed development. Applying functional connectivity and graph theory methods to resting state MRI data (fcMRI), we tested the hypothesis that preterm infants would demonstrate alterations in connectivity measures both globally and in specific networks related to motor, language and cognitive function, even when there is no anatomical imaging evidence of injury. Fifty-one healthy full-term controls and 24 very preterm infants without significant neonatal brain injury, were evaluated at term-equivalent age with fcMRI. Preterm subjects showed lower functional connectivity from regions associated with motor, cognitive, language and executive function, than term controls. Examining brain networks using graph theory measures of functional connectivity, very preterm infants also exhibited lower rich-club coefficient and assortativity but higher small-worldness and no significant difference in modularity when compared to term infants. The findings provide evidence that functional connectivity exhibits deficits soon after birth in very preterm infants in key brain networks responsible for motor, language and executive functions, even in the absence of anatomical lesions. These functional network measures could serve as prognostic biomarkers for later developmental disabilities and guide decisions about early interventions.

Cognitive outcomes in children and adolescents born very preterm: a meta-analysis

AIM

To estimate the association between very preterm birth (<32wks' gestation) and intelligence, executive functioning, and processing speed throughout childhood and adolescence, and to examine the effects of gestational age, birthweight, and age at assessment.

METHOD

Studies were included if children were born at earlier than 32 weeks' gestation, aged 4 to 17 years, had an age-matched term control group, and if the studies used standardized measures, were published in an English-language peer-reviewed journal, and placed no restrictions on participants based on task performance.

RESULTS

We evaluated 6163 children born very preterm and 5471 term-born controls from 60 studies. Children born very preterm scored 0.82 SDs (95% confidence interval [CI] 0.74-0.90; p<0.001) lower on intelligence tests, 0.51 SDs (95% CI 0.44-0.58; p<0.001) lower on measures of executive functioning, and 0.49 SDs (95% CI 0.39-0.60; p<0.001) lower on measures of processing speed than term-born controls. Gestational age and birthweight were associated with study effect size in intelligence and executive functioning of younger children only. Age at assessment was not associated with study effect size.

INTERPRETATION

Children born very preterm have medium to large deficits in these cognitive domains.

WHAT THIS PAPER ADDS

This meta-analysis is centred on very preterm birth and three cognitive domains. The three critical cognitive domains are intelligence, executive functioning, and processing speed.

Long-term neuroprotective effect of erythropoietin on executive functions in very preterm children (EpoKids): protocol of a prospective follow-up study

INTRODUCTION

Premature infants are particularly vulnerable to brain injuries with associated cognitive and behavioural deficits. The worldwide first randomised interventional multicentre trial investigating the neuroprotective effects of erythropoietin (entitled 'Does erythropoietin improve outcome in very preterm infants?' (NCT00413946)) included 450 very preterm infants in Switzerland. MRI at term equivalent age showed less white matter (WM) injury in the erythropoietin group compared with the placebo group. Despite these promising imaging findings, neurodevelopmental outcome at 2 years showed no beneficial effect of early erythropoietin. One explanation could be that the assessment of more complex cognitive functions such as executive functions (EFs) is only possible at a later age. We hypothesise that due to improved WM development and fewer WM injuries, children born preterm treated with early erythropoietin will have better EF abilities at 7-12 years than those treated with placebo.

METHODS AND ANALYSIS

365 children who were included into the primary analysis of the original trial (NCT00413946) will be eligible in this prospective follow-up study at the age of 7-12 years. 185 children born at term will be control children. Primary outcome measures are EF abilities and processing speed, while secondary outcomes are academic performance, IQ, fine motor abilities and global brain connectivity. A comprehensive test battery will be applied to assess EFs. MRI will be performed to assess global brain connectivity. Cognitive scores and MRI measures will be compared between both groups using the Wilcoxon test. Propensity score matching will be used to balance gender, age, socioeconomic status and other potentially unbalanced variables between the children born preterm and the healthy control children.

ETHICS AND DISSEMINATION

The cantonal ethical committee granted ethical approval for this study (KEK 2017-00521). Written consent will be obtained from the parents. Findings from this study will be disseminated via international and national conference presentations and publications in peer-reviewed journals.

Antenatal and Neonatal Antecedents of Executive Dysfunctions in Extremely Preterm Children

To find out why children born extremely preterm are at heightened risk of executive dysfunctions, the authors assessed 716 children who were 10 years old born extremely preterm whose IQ was ≥ 70. A working memory dysfunction (n = 169), an inhibition dysfunction (n = 360), a switching dysfunction (355), and all 3 (executive dysfunction; n = 107) were defined on the basis of Z-scores ≤ -1 on the Differential Ability Scales-II Working Memory composite, and/or on the NEPSY-II Inhibition-Inhibition and Inhibition-Switching subtests. All risk profiles include an indicator of socioeconomic disadvantage. The risk profile of each of the 3 individual dysfunctions includes an indicator of the newborn's immaturity, and the risk profiles of the inhibition dysfunction and switching dysfunction also include an indicator of inflammation. Only the switching dysfunction was associated with fetal growth restriction. The risk factors for executive dysfunction can be subsumed under the 4 themes of socioeconomic disadvantage, immaturity/vulnerability, inflammation, and fetal growth restriction.

Do Infants Born Very Premature and Who Have Very Low Birth Weight Catch Up With Their Full Term Peers in Their Language Abilities by Early School Age?

PURPOSE

This study examined the extent to which children born preterm (< 37 weeks) and/or who have low birth weight (< 2,500 g) catch up with their full term peers in terms of their language abilities at early school age (≥ 5 to < 9 years).

METHOD

A systematic literature search identified empirical studies that fit the inclusion criteria. Data from the tests/questionnaires used for meta-analysis spanned the following language categories: total language score, expressive language, receptive language, pragmatics, phonological awareness, and grammar. The means (standard deviations) were extracted from the studies and were converted to mean difference and 95% confidence intervals to test for overall effect.

RESULTS

Sixteen studies met the inclusionary criteria, for a total of 2,739 participants, of which 1,224 were born full term and 1,515 were born preterm. It is important to note that the preterm cohort represented very preterm infants who have a very low birth weight. The meta-analysis found that preterm infants scored significantly worse on total language (p < .001), receptive language (p < .001), expressive language (p < .001), phonological awareness (p < .001), and grammar (p = .03) than their full term peers. However, preterm infants did not score significantly worse than their peers on their pragmatics (p = .19).

CONCLUSIONS

Children born VPT and who have VLBW perform worse than their peers on their total language, receptive language, expressive language, phonological awareness, and grammar abilities by early school age. This information is important for speech-language pathologists to consider as children born prematurely reach school age.

Executive functioning in low birth weight children entering kindergarten

OBJECTIVES

Poor executive functioning is associated with life-long difficulty. Identification of children at risk for executive dysfunction is important for early intervention to improve neurodevelopmental outcomes.

STUDY DESIGN

This study is designed to examine relationships between birthweight and executive functioning in US children during kindergarten. Our hypothesis was that children with higher birthweights would have better executive function scores. We evaluated data from 17506 US children from the Early Childhood Longitudinal Study-Kindergarten 2011 cohort. Birthweight and gestational age were obtained by parental survey. Executive functions were directly assessed using the number reverse test and card sort test to measure working memory and cognitive flexibility, respectively. Teacher evaluations were used for additional executive functions. Data were analyzed using SAS to run all linear and logistical regressions.

RESULTS

For every kilogram of birthweight, scores of working memory increased by 1.47 (P<0.001) and cognitive flexibility increased by 0.28 (P<0.001) independent of gender, gestational age, parental education, and family income. Low birthweight infants were 1.5 times more likely to score in the bottom 20% of children on direct assessment OR=1.49 (CI 1.21-1.85) and OR=1.55 (CI 1.26-1.91).

CONCLUSIONS

Infants born low birthweight are at increased risk of poor executive functioning. As birthweight increases executive function scores improve, even among infants born normal weight. Further evaluation of this population including interventions and progression through school is needed.

Trends in Executive Functioning in Extremely Preterm Children Across 3 Birth Eras

BACKGROUND AND OBJECTIVES

To determine if executive functioning outcomes at school age are different for extremely preterm (EP; <28 weeks' gestation) or extremely low birth weight (ELBW; <1000 g birth weight) children born in 1991 to 1992, 1997, and 2005 relative to their term-born peers.

METHODS

Population-based cohorts of all EP/ELBW survivors born in the state of Victoria, Australia, in 1991 to 1992, 1997, and 2005, and contemporaneous controls (matched for expected date of birth, sex, mother's country of birth [English speaking or not], and health insurance status) were recruited at birth. At 7 to 8 years of age, parents of 613 children who were EP/ELBW and 564 children who were controls rated their children's executive functioning on the Behavior Rating Inventory of Executive Function (BRIEF). The proportion of children with elevated BRIEF scores (in the clinically significant range) in each birth group and era was compared by using logistic regression. Sensitivity analyses explored these associations after excluding children with intellectual impairment.

RESULTS

Across the eras, EP/ELBW children had higher rates of elevated scores than controls in almost all BRIEF domains. The 2005 EP/ELBW cohort had increased executive dysfunction compared with earlier cohorts, particularly in working memory and planning and organization. This effect persisted after accounting for demographic factors and weakened slightly when those with intellectual impairment were excluded.

CONCLUSIONS

These results indicate a concerning trend of increasing executive dysfunction for EP/ELBW children who were born more recently. This may have adverse implications for other functional domains, such as academic achievement and social-emotional well-being.

Neuropsychological assessment and perinatal risk: A study amongst very premature born 4- and 5-year old children

BACKGROUND

Prematurity and its consequences are serious problems that can result in numerous neurosensory disabilities and cerebral cognitive dysfunctions. The Perinatal Risk Index (PERI) might provide a predictive measure of these problems.

AIM

This study compared the cognitive development of prematurely born children at 4 and 5 years of age with age-matched peers born at term. The secondary objective was to determine whether a correlation exists between perinatal risk and performance on neuropsychological tests among premature children.

METHODS

A total of 54 children between four and five years of age were evaluated; 27 were born very premature (premature group; PG), and 27 were born at term (term group; TG). Executive function, attention, memory, language, visual perception, and spatial structuring were evaluated. Subtests from the Kaufman Assessment Battery for Children, the Rey Complex Figure Test, the McCarthy Scales of Children's Abilities, the Peabody Picture Vocabulary Test, Test A, Trails A and B, the spatial structuring questionnaire from the Child Neuropsychological Maturity Questionnaire, and the Wechsler Intelligence Scale for Children were used. A PERI score was also obtained for the PG.

RESULTS

The PG showed significantly lower scores than the TG in all the studied cognitive domains. Visual-perceptive scores were significantly and negatively correlated with the PERI scores of the PG.

CONCLUSIONS

The PG showed neurocognitive deficits compared with the TG. The PERI can be used to predict the development of visual-perceptive abilities in children between four and five years of age.

Executive Function and Academic Outcomes in Children Who Were Extremely Preterm

OBJECTIVES

Cognitive and behavioral impairments of children born extremely preterm (EP) (<28 weeks' gestation) and extremely low birth weight (ELBW) (<1000 g) may change with age. We assessed the individual stability of behavioral executive function (EF) from 8 to 18 years of age in children born EP or ELBW and their academic outcomes.

METHODS

Participants comprised 180 children born EP or ELBW from a large geographic cohort. We investigated the frequency of 4 developmental groups (persistent, remitting, late-onset, and typical development) on the basis of dichotomized scores (typical versus elevated) at ages 8 and 18 years in 2 indices (the Behavioral Regulation Index [BRI] and the Metacognition Index [MCI]) of the parental form of the Behavior Rating Inventory of Executive Function. Adolescent academic outcomes were measured by using the word reading, spelling, and math computation subtests of the Wide Range Achievement Test, Fourth Edition.

RESULTS

Most participants had a typical EF (BRI 61%, MCI 53%), followed by persistent (BRI 15%, MCI 16%), late-onset (BRI 12%, MCI 19%), or remitting (BRI 12%, MCI 13%) executive difficulties. Groups with executive impairments at age 18 years (persistent and late onset) had poorer academic outcomes than the typical and remitting groups. Shifting impairment categories between 8 and 18 years old was relevant to later academic outcomes.

CONCLUSIONS

Most children showed stable and age-appropriate EF, although persistent and transient difficulties were observed and related to uneven academic outcomes. Studying the origins and consequences of the developmental stability of EF may contribute to the development of interventions to decrease the adverse neurodevelopmental outcomes of preterm birth.

Correlation between white matter microstructure and executive functions suggests early developmental influence on long fibre tracts in preterm born adolescents

Main objectives

Executive functions are frequently a weakness in children born preterm. We examined associations of executive functions and general cognitive abilities with brain structure in preterm born adolescents who were born with appropriate weight for gestational age and who have no radiological signs of preterm brain injury on neuroimaging.

Methods

The Stockholm Neonatal Project (SNP) is a longitudinal, population-based study of children born preterm (<36 weeks of gestation) with very low birth weight (<1501g) between 1988–1993. At age 18 years (mean 18 years, SD 2 weeks) 134 preterm born and 94 full term participants underwent psychological assessment (general intelligence, executive function measures). Of these, 71 preterm and 63 full term participants underwent Magnetic Resonance Imaging (MRI) at mean 15.2 years (range 12–18 years), including 3D T1-weighted images for volumetric analyses and Diffusion Tensor Imaging (DTI) for assessment of white matter microstructure. Group comparisons of regional grey and white matter volumes and fractional anisotropy (FA, as a measure of white matter microstructure) and, within each group, correlation analyses of cognitive measures with MRI metrics were carried out.

Results

Significant differences in grey and white matter regional volumes and widespread differences in FA were seen between the two groups. No significant correlations were found between cognitive measures and brain volumes in any group after correction for multiple comparisons. However, there were significant correlations between FA in projection fibres and long association fibres, linking frontal, temporal, parietal, and occipital lobes, and measures of executive function and general cognitive abilities in the preterm born adolescents, but not in the term born adolescents.

Overall significance of the study

In persons born preterm, in the absence of perinatal brain injury on visual inspection of MRI, widespread alterations in regional brain tissue volumes and microstructure are present in adolescence/young adulthood. Importantly, these alterations in WM tracts are correlated with measures of executive function and general cognitive abilities. Our findings suggest that disturbance of neural pathways, rather than changes in regional brain volumes, are involved in the impaired cognitive functions.

The impact of preterm birth <37 weeks on parents and families: a cross-sectional study in the 2 years after discharge from the neonatal intensive care unit

BACKGROUND

Little is known about the quality of life of parents and families of preterm infants after discharge from the neonatal intensive care unit (NICU). Our aims were (1) to describe the impact of preterm birth on parents and families and (2) and to identify potentially modifiable determinants of parent and family impact.

METHODS

We surveyed 196 parents of preterm infants <24 months corrected age in 3 specialty clinics (82% response rate). Primary outcomes were: (1) the Impact on Family Scale total score; and (2) the Infant Toddler Quality of Life parent emotion and (3) time limitations scores. Potentially modifiable factors were use of community-based services, financial burdens, and health-related social problems. We estimated associations of potentially modifiable factors with outcomes, adjusting for socio-demographic and infant characteristics using linear regression.

RESULTS

Median (inter-quartile range) infant gestational age was 28 (26-31) weeks. Higher Impact on Family scores (indicating worse effects on family functioning) were associated with taking ≥3 unpaid hours/week off from work, increased debt, financial worry, unsafe home environment and social isolation. Lower parent emotion scores (indicating greater impact on the parent) were also associated with social isolation and unpaid time off from work. Lower parent time limitations scores were associated with social isolation, unpaid time off from work, financial worry, and an unsafe home environment. In contrast, higher parent time limitations scores (indicating less impact) were associated with enrollment in early intervention and Medicaid.

CONCLUSIONS

Interventions to reduce social isolation, lessen financial burden, improve home safety, and increase enrollment in early intervention and Medicaid all have the potential to lessen the impact of preterm birth on parents and families.

Association of Preterm Birth With Attention-Deficit/Hyperactivity Disorder-Like and Wider-Ranging Neurophysiological Impairments of Attention and Inhibition

OBJECTIVE

Preterm birth has been associated with an increased risk of attention-deficit/hyperactivity disorder (ADHD)-like symptoms and cognitive impairments similar to those seen in ADHD, including attention and inhibitory control difficulties. Yet data on direct comparisons across ADHD and preterm birth on cognitive-neurophysiological measures are limited.

METHOD

We directly compared 186 preterm-born adolescents to 69 term-born adolescents with ADHD and 135 term-born controls on cognitive-performance and event-related potential measures associated with attentional and inhibitory processing from a cued continuous performance test (CPT-OX), which we have previously shown to discriminate between the adolescents with ADHD and controls. We aimed to elucidate whether the ADHD-like symptoms and cognitive impairments in preterm-born individuals reflect identical cognitive-neurophysiological impairments in term-born individuals with ADHD.

RESULTS

Go-P3 amplitude was reduced, reflecting impaired executive response control, in preterm-born adolescents compared to both controls and adolescents with ADHD. Moreover, in preterm-born adolescents, as in term-born adolescents with ADHD, contingent negative variation amplitude was attenuated, reflecting impairments in response preparation compared to controls. Although the ADHD group showed significantly increased NoGo-P3 amplitude at FCz compared to preterm group, at Cz preterm-born adolescents demonstrated significantly decreased NoGo-P3 amplitude compared to the control group, similar to term-born adolescents with ADHD.

CONCLUSION

These findings indicate impairments in response preparation, executive response control, and response inhibition in preterm-born adolescents. Although the response preparation and response inhibition impairments found in preterm-born adolescents overlap with those found in term-born adolescents with ADHD, the preterm group also shows unique impairments, suggesting more wide-ranging impairments in the preterm group compared to the ADHD group.

Early and long-term outcome of infants born extremely preterm

There is no question that birth at extremely low gestational ages presents a significant threat to an infant's survival, health and development. Growing evidence suggests that gestational age may be conceptualised as a continuum in which births before 28 weeks of gestation (extremely preterm: EP) represent the severe end of a spectrum of health and developmental adversity. Although comprising just 1%-2% of all births, EP deliveries pose the greatest challenge to neonatal medicine and to health, education and social services for the provision of ongoing support for survivors with additional needs. Studying the outcomes of these infants remains critical for evaluating and enhancing clinical care, planning long-term support and for advancing our understanding of the life-course consequences of immaturity at birth. Here we review literature relating to early and long-term neurodevelopmental, cognitive, behavioural and educational outcomes following EP birth focusing on key themes and considering implications for intervention.

Association of Gestational Age With Verbal Ability and Spatial Working Memory at Age 11

BACKGROUND

Although children born very preterm (gestation <32 weeks) have an increased risk of cognitive impairment compared with full-term children (39-41 weeks), the risk for children born moderately (32-33 weeks) to late preterm (34-36 weeks) and early term (37-38 weeks) is unclear. This study describes the relationship between gestational age and cognitive outcomes at 11 years and the trajectory of deficits in verbal ability from age 3 to 11 years.

METHODS

Cognitive ability was assessed by using the Spatial Working Memory test from the Cambridge Neuropsychological Test Automated Working Battery (n = 11 395) and British Ability Scale Verbal Similarities test (n = 11 889) in the UK Millennium Cohort Study. Each gestational group was compared with the full-term group by using differences in z scores and odds ratios for delay (scoring ≥1 SD below the mean).

RESULTS

Very and moderately preterm children demonstrated significantly lower working memory scores compared with full-term children (adjusted difference -0.2 to -0.6) and were more likely to be delayed. There was no significant relationship between late-preterm or early-term birth and working memory (adjusted differences < -0.1), or between gestational age and verbal ability at 11 years. There appears to be a general attenuation in odds ratios as the child ages.

CONCLUSIONS

Very preterm children exhibited working memory deficits at 11 years. However, the absence of delayed verbal skills at 11 years despite earlier delays could indicate "catch-up" effects.

Learning disabilities among extremely preterm children without neurosensory impairment: Comorbidity, neuropsychological profiles and scholastic outcomes

BACKGROUND

Children born extremely preterm are at high risk for intellectual disability, learning disabilities, executive dysfunction and special educational needs, but little is understood about the comorbidity of intellectual and learning disabilities in this population.

AIMS

This study explored comorbidity in intellectual disability (ID) and learning disabilities (LD) in children born extremely preterm (EP; <26⁺⁰weeks' gestation).

SUBJECTS AND STUDY DESIGN

A UK national cohort of 161 EP children and 153 term-born controls without neurosensory impairments was assessed at 11years of age (the EPICure Study).

OUTCOME MEASURES

IQ, mathematics and reading attainment, executive function, visuospatial processing and sensorimotor skills were assessed using standardised tests, and curriculum-based attainment and special educational needs (SEN) using teacher reports.

RESULTS

Overall, 75 (47%) EP children and 7 (4.6%) controls had ID or LD (RR 10.12; 95% CI 4.81, 21.27). Comorbidity in ID/LD was more common among EP children than controls (24% vs. 0%). EP children with comorbid ID/LD had significantly poorer neuropsychological abilities and curriculum-based attainment than EP children with an isolated disability or no disabilities. LD were associated with a 3 times increased risk for SEN. However, EP children with ID alone had poorer neuropsychological abilities and curriculum-based attainment than children with no disabilities, yet there was no increase in SEN provision among this group.

CONCLUSIONS

EP children are at high risk for comorbid intellectual and learning disabilities. Education professionals should be aware of the complex nature of EP children's difficulties and the need for multi-domain assessments to guide intervention.

Executive function in children born preterm: Risk factors and implications for outcome

Executive function (EF) refers to the set of cognitive processes involved in the self-regulation of emotion and goal-directed behavior. These skills and the brain systems that support them develop throughout childhood and are frequently compromised in preterm children, even in those with broadly average global cognitive ability. Risks for deficits in EF in preterm children and attendant problems in learning and psychosocial functioning are higher in those with more extreme prematurity, neonatal complications, and related brain abnormalities. Associations of higher levels of EF with more supportive home and school environments suggest a potential for attenuating these risks, especially with early identification. Further research is needed to understand how deficits in EF evolve in preterm children, refine assessment methods, and develop interventions that either promote the development of EF in this population or help children to compensate for these weaknesses.

Is Self-Regulation "All in the family"? Testing Environmental Effects using Within-Family Quasi-Experiments

Most of the individual difference variance in the population is found within families, yet studying the processes causing this variation is difficult due to confounds between genetic and nongenetic influences. Quasi-experiments can be used to test hypotheses regarding environment exposure (e.g., timing, duration) while controlling for genetic confounds. To illustrate, two studies of cognitive self-regulation in childhood (i.e., working memory [WM], effortful control [EC], attention span/persistence [A/P]) are presented. Study 1 utilized an identical twin differences design (N = 85 to 98 pairs) to control for genetic differences while using relative twin birth weight difference to predict relative twin difference in WM and EC. Larger relative twin difference in WM and EF was predicted by the combination of shorter gestation and larger relative birth weight difference. Study 2 utilized an adoptive sibling relative difference design (N = 123 same-sex pairs) to control for genetic similarity while using relative sibling difference in the age at time of adoption to predict relative sibling difference in A/P. Larger relative sibling difference in A/P was predicted by the combination of larger relative difference in time in the adoptive home and age at adoption. Within-family quasi-experimental designs allow stronger inferences about hypothesized environmental influences than between-family designs permit.

[Nutritional status of adolescents from a cohort of preterm children]

INTRODUCTION

Catch-up growth in preterm-born children occurs in the first months of life, but in some cases, growth recovery takes place in adolescence. The objective of this study was to study the growth and development of preterm-born adolescents from a cohort of preterm infants born between 1995 and 1996, who resided in the cities of Chillán and San Carlos in the Biobío Region, Chile. The results were then compared with term-born adolescents.

SUBJECTS AND METHOD

A sample of 91 children from the cohort was studied and compared with 91 term-born adolescents matched for gender, age, and attendance at the same educational institution. The nutritional status was assessed by BMI-for-age, height-for-age, body composition by skinfold, cardiovascular risk due to blood pressure, and waist circumference.

RESULTS

There was 23.0% and 24.1% overweight and obesity in preterm-born and term-born adolescents, respectively, with 25.5% of preterm-born and small for gestational age adolescents vs. 14.5% of those born adequate for gestational age were overweight. Lower height was observed in 16.5% and 5.5% of the preterm-born and term-born adolescents, respectively, and with a higher proportion of girls (P<.04). Preterm-born adolescents had a more fat mass than the controls, particularly in the suprailiac skinfold. No significant differences were found in blood pressure and waist circumference.

CONCLUSIONS

The results indicate that there is a group of preterm-born children who do not recover height during adolescence, especially girls.

Very preterm adolescents show impaired performance with increasing demands in executive function tasks

BACKGROUND

Very preterm birth is often associated with executive function deficits later in life. The transition to adolescence increases personal autonomy, independence and, in parallel, the demands placed on executive functions at home and in school.

AIM

To assess the impact of increasing demands on executive function performance in very preterm children and adolescents with normal intellectual and motor functions.

METHODS

Forty-one very preterm children and adolescents with normal intellectual and motor functions and 43 healthy term-born peers were assessed at a mean age of 13.0 years (SD: 1.9; range: 10.0-16.9). A comprehensive battery of performance-based executive function measures with different demand levels as well as a parent-rating questionnaire evaluating executive functions relevant for everyday life was applied. Standardized mean differences between groups of d ≥ .41 were regarded as clinically relevant.

RESULTS

No group differences were found at the lowest demand levels of working memory (d=.09), planning (d=-.01), cognitive flexibility (d=-.21) and verbal fluency (d=-.14) tasks, but very preterm participants scored significantly below their term-born peers in the most demanding levels (d=-.50, -.59, -.43 and -.55, respectively). These differences were clinically relevant. Executive functions relevant for everyday life were strongly impaired in very preterm participants, e.g., global executive composite (d=-.66).

CONCLUSION

Very preterm children and adolescents with normal intellectual and motor functions are at high risk for executive function deficits that may only become apparent with increasing demands, potentially leading to academic and other deficits.