Neuropsychological abilities underpinning academic attainment in children born extremely preterm.

Children born extremely preterm (EP) have poorer academic attainment than their term-born peers. There is a need to identify the specific cognitive mechanisms that are associated with poor academic attainment in preterm populations to inform the development of intervention strategies. A parallel mediation analysis was conducted with cross-sectional data from 152 EP children (< 27 weeks of gestation) and 120 term-born controls who were assessed at age 11. Mathematics and reading attainment was assessed using the Wechsler Individual Achievement Test 2nd Edition. Controlling for sex and socio-economic status we evaluated the following mediators: verbal working memory, visuospatial working memory, verbal processing speed, attention, and visuospatial processing. These were assessed using subtests from the standardized NEPSY-II test and Wechsler Intelligence Scale for Children-5th Edition. Verbal working memory, visuospatial working memory, visuospatial processing and verbal processing speed, but not attention, were significant independent mediators between EP birth and attainment in reading. No direct relationship between EP birth and reading attainment remained in the mediated model. All five neuropsychological variables mediated the relationship between EP birth and attainment in mathematics, but a direct effect of EP birth on mathematics remained in the mediated model. Together, all five neuropsychological abilities indirectly explained 44% of the variance in reading and 52% of the variance in mathematics. Visuospatial processing was the strongest mediator of both mathematics and reading. Components of executive function, especially visuospatial processing, are important predictors of academic attainment. Interventions to improve visuospatial skills could be trialed in EP populations.

Growth in extremely preterm children born in England in 1995 and 2006: the EPICure studies.

OBJECTIVES: To determine growth outcomes at 11 years of age in children born <27 weeks of gestation in England in 2006 (EPICure2) and to compare growth from birth to 11 years of age for births<26 weeks with those in England in 1995 (EPICure). METHODS: 200 EPICure2 children assessed at 11 years alongside 143 term-born controls. Growth measures from birth to 11 years were compared for births<26 weeks between EPICure2 (n=112) and EPICure (n=176). Growth parameter z-scores were derived from 1990 UK standards. RESULTS: Among EPICure2 children, mean z-scores for height and weight were close to the population standards (0.08 and 0.18 SD, respectively) but significantly below those of controls: difference in mean (Δ) z-scores for weight -0.42 SD (95% CI -0.68 to -0.17), for height -0.45 SD (-0.70 to -0.20) and for head circumference (HC) -1.05 SD (-1.35 to -0.75); mean body mass index (BMI) z-score in EPICure2 children was 0.18 SD, not significantly different from controls (0.43 SD, p=0.065). Compared with EPICure, EPICure2 children born <26 weeks at 11 years had higher z-scores for weight (Δ 0.72 (0.47, 0.96)), height (Δ 0.55 (0.29, 0.81)) and BMI (Δ 0.56 (0.24, 0.87)), which were not fully explained by perinatal/demographic differences between eras. Weight catch-up was greater from term-age to 2.5/3 years in EPICure2 than in EPICure (1.25 SD vs 0.53 SD; p<0.001). Poor HC growth was observed in EPICure2, unchanged from EPICure. CONCLUSIONS: Since 1995, childhood growth in weight, height and BMI have improved for births <26 weeks of gestation, but there was no improvement in head growth.

Disturbed sleep in children born extremely preterm is associated with behavioural and emotional symptoms.

AIM: To determine whether children born extremely preterm are at increased risk for sleep disturbances and to explore relationships between extremely preterm birth, sleep and attention-deficit/hyperactivity disorder (ADHD) symptoms and emotional symptoms. METHOD: EPICure2 cohort study. Parents of 165 children born ≤26 weeks' gestation (53% male) and 121 children born at term (43% male) completed the Children's Sleep Habits Questionnaire, sleep disordered breathing subscale of the Pediatric Sleep Questionnaire, the emotional problems scale of the Strengths and Difficulties Questionnaire and the ADHD Rating Scale-5 at 11 years of age. RESULTS: Extremely preterm children had greater habitual snoring (adjusted odds ratio 6.8; 95% confidence interval 2.3, 20.3), less frequently fell asleep within 20 minutes (Cohen's d 0.33), higher night wakings (d 0.44) and daytime sleepiness scores (d 0.40) than term-born children; there was no between-group difference in sleep duration scores. Among children without severe disability, night wakings scores partially mediated the relationship between preterm birth and inattention (additional 5% of variance explained), hyperactivity/impulsivity (13%) and emotional problems (9%). Snoring partially mediated the relationship between preterm birth, hyperactivity/impulsivity and inattention (additional 1-5% of variance). CONCLUSION: Children born extremely preterm are at increased risk of disturbed sleep compared to term-born children. As night wakings partially mediated the relationship between preterm birth and ADHD symptoms and emotional problems, reducing sleep disturbance may improve sleep and reduce attention and emotional problems in this population.

No change in neurodevelopment at 11 years after extremely preterm birth.

OBJECTIVE: To determine whether improvements in school age outcomes had occurred between two cohorts of births at 22-25 weeks of gestation to women residents in England in 1995 and 2006. DESIGN: Longitudinal national cohort studies. SETTING: School-based or home-based assessments at 11 years of age. PARTICIPANTS: EPICure2 cohort of births at 22-26 weeks of gestation in England during 2006: a sample of 200 of 1031 survivors were evaluated; outcomes for 112 children born at 22-25 weeks of gestation were compared with those of 176 born in England during 1995 from the EPICure cohort. Classroom controls for each group acted as a reference population. MAIN OUTCOME MEASURES: Standardised measures of cognition and academic attainment were combined with parent report of other impairments to estimate overall neurodevelopmental status. RESULTS: At 11 years in EPICure2, 18% had severe and 20% moderate impairments. Comparing births at 22-25 weeks in EPICure2 (n=112), 26% had severe and 21% moderate impairment compared with 18% and 32%, respectively, in EPICure. After adjustment, the OR of moderate or severe neurodevelopmental impairment in 2006 compared with 1995 was 0.76 (95% CI 0.45 to 1.31, p=0.32). IQ scores were similar in 1995 (mean 82.7, SD 18.4) and 2006 (81.4, SD 19.2), adjusted difference in mean z-scores 0.2 SD (95% CI -0.2 to 0.6), as were attainment test scores. The use of multiple imputation did not alter these findings. CONCLUSION: Improvements in care and survival between 1995 and 2006 are not paralleled by improved cognitive or educational outcomes or a reduced rate of neurodevelopmental impairment.

An Exploration of the Factor Structure of Executive Functioning in Children.

There has been considerable debate and interest in the factor structure of executive functioning (EF). For children and young people, there is evidence of a progression from a single factor to a more differentiated structure, although the precise nature of these factors differs between investigations. The purpose of the current study was to look at this issue again with another sample, and try to understand possible reasons for previous differences between investigations. In addition, we examined the relationship between less central EF tasks, such as fluency and planning, to the more common tasks of updating/executive working memory (EWM), inhibition, and switching/shifting. A final aim was to carry out analyses which are relevant to the debate about whether EF is influenced by language ability, or language ability is influenced by EF. We reasoned that if language ability affects EF, a factor analysis of verbal and non-verbal EF tasks might result in the identification of a factor which predominantly contains verbal tasks and a factor that predominately contains non-verbal tasks. Our investigation involved 128 typically developing participants (mean age 10:4) who were given EF assessments that included verbal and non-verbal versions of each task: EWM; switching; inhibition; fluency; and planning. Exploratory factor analyses on EWM, switching, and inhibition produced a structure consisting of inhibition in one factor and the remaining tasks in another. It was decided to exclude verbal planning from the next analyses of all the ten tasks because of statistical considerations. Analysis of the remaining nine EF tasks produced two factors, one factor containing the two inhibition tasks, and another factor that contained all the other tasks (switching, EWM, fluency, and non-verbal planning). There was little evidence that the verbal or non-verbal elements in these tasks affected the factor structure. Both these issues are considered in the discussion, where there is a general evaluation of findings about the factor structure of EF.

Executive functions in children with developmental coordination disorder: a 2-year follow-up study.

AIM: Executive function impairments have been identified in children with poor motor skills, with and without a diagnosis of developmental coordination disorder (DCD). However, most studies are cross-sectional. This study investigates the development of executive function in children with poor motor skills over 2 years. METHOD: Children aged 7 to 11 years (n=51) were assessed twice, 2 years apart, on verbal and nonverbal measures of executive functions: executive-loaded working memory (ELWM); fluency; response inhibition; planning; and cognitive flexibility. Typically developing children (n=17) were compared with those with a clinical diagnosis of DCD (n=17) and those with identified motor difficulties (n=17) but no formal diagnosis of DCD. RESULTS: Developmental gains in executive function were similar between groups, although a gap between children with poor motor skills and typically developing children on nonverbal executive functions persisted. Specifically, children with DCD performed significantly more poorly than typically developing children on all nonverbal executive function tasks and verbal fluency tasks at both time points; and children with motor difficulties but no diagnosis of DCD showed persistent executive function problems in nonverbal tasks of ELWM and fluency. INTERPRETATION: Children with DCD and motor difficulties demonstrated executive function difficulties over 2 years, which may affect activities of daily living and academic achievement, in addition to their motor deficit. WHAT THIS PAPER ADDS: Executive function difficulties in children with poor motor skills persist throughout middle childhood. Children with motor difficulties, without a developmental coordination disorder (DCD) diagnosis, demonstrate less pervasive executive function difficulties than those with DCD. Executive function problems in the groups with motor difficulties and DCD affect mostly nonverbal domains. All groups showed similar developmental gains in executive function.

Brief report: Response inhibition and processing speed in children with motor difficulties and developmental coordination disorder.

A previous study reported that children with poor motor skills, classified as having motor difficulties (MD) or Developmental Coordination Disorder (DCD), produced more errors in a motor response inhibition task compared to typically developing (TD) children but did not differ in verbal inhibition errors. The present study investigated whether these groups differed in the length of time they took to respond in order to achieve these levels of accuracy, and whether any differences in response speed could be explained by generally slow information processing in children with poor motor skills. Timing data from the Verbal Inhibition Motor Inhibition test were analyzed to identify differences in performance between the groups on verbal and motor inhibition, as well as on processing speed measures from standardized batteries. Although children with MD and DCD produced more errors in the motor inhibition task than TD children, the current analyses found that they did not take longer to complete the task. Children with DCD were slower at inhibiting verbal responses than TD children, while the MD group seemed to perform at an intermediate level between the other groups in terms of verbal inhibition speed. Slow processing speed did not account for these group differences. Results extended previous research into response inhibition in children with poor motor skills by explicitly comparing motor and verbal responses, and suggesting that slow performance, even when accurate, may be attributable to an inefficient way of inhibiting responses, rather than slow information processing speed per se.

Executive Functioning, Motor Difficulties, and Developmental Coordination Disorder.

The current study assessed a comprehensive range of executive functions (EFs) in children with poor motor skills, comparing profiles of children with a diagnosis of developmental coordination disorder (DCD) and those identified with motor difficulties (MD). Children in both groups performed more poorly than typically developing controls on nonverbal measures of working memory, inhibition, planning, and fluency, but not on tests of switching. The similar patterns of strengths and weaknesses in children with MD and DCD have important implications for parents, teachers, and clinicians, as children with MD may struggle with EF tasks even though their motor difficulties are not identified.