Elsevier

Early Human Development

Volume 103, December 2016, Pages 69-75
Early Human Development

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

https://doi.org/10.1016/j.earlhumdev.2016.07.009Get rights and content

Highlights

  • EP children are at increased risk for learning difficulties in mathematics, but not reading.

  • Comorbidity in intellectual and learning disabilities is common among EP children.

  • Intellectual and learning disabilities are associated with poor executive function, visuo-spatial and sensori-motor skills.

  • Professionals should be aware of the need for multi-domain assessments to guide intervention.

Abstract

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+ 0 weeks' gestation).

Subjects and study design

A UK national cohort of 161 EP children and 153 term-born controls without neurosensory impairments was assessed at 11 years 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.

Introduction

Extremely preterm birth (EP; < 26+ 0 weeks' gestation) places children at high risk for neurodevelopmental disability and intellectual impairment later in life, and there is growing interest in educational outcomes as key predictors of an individual's life chances. The poorest scholastic outcomes are observed among those born EP [1], [2], [3], with up to two thirds having special educational needs (SEN) [4], [5]. Moreover, SEN are not confined only to EP children with severe disabilities [5], [6], [7], [8], [9].

Studies using low attainment definitions have shown an increased risk for learning difficulties (LD) in EP or extremely low birthweight (ELBW;<1000 g) children compared with term-born peers [5], [7], [10], [11], [12], [13]. There is also evidence of an increased risk for specific LD in these populations where discrepancy based definitions are applied, the most frequent of which are mathematics learning difficulties (MLD) [7], [8], [10], [13]. In contrast to reading and literacy, group differences in mathematics attainment are frequently not accounted for by low IQ [5], [6], [10], [14]. Other neuropsychological processes such as attention, executive function, sensori-motor and visuo-spatial skills contribute to scholastic attainment in typically developing and preterm children [7], [10], [15], [16], [17], [18] and may be core cognitive deficits in this population [19], [20], [21].

Previous studies have also shown that EP/ELBW children are more likely to have impairments in multiple neurodevelopmental domains, such as in neurological, motor, cognitive and behavioural function, than children born at term [12], [22]. However, comorbidity among intellectual and learning disabilities is poorly understood. Where studies have been conducted, a greater frequency of comorbid intellectual disability (ID) and LD has been observed in very preterm preschoolers (< 32 weeks' gestation) compared with term-born controls [23], [24]. At school age, ELBW has been associated with an increased risk for comorbidity of LD in mathematics and reading [7], but this study included only a small sample of ELBW children without ID and the children were born in the 1970s, before the dawn of modern neonatal care. More recently, children born < 34 weeks' gestation have been shown to have comorbid LD at early school age [8].

As yet, we are not aware of any studies that have explored patterns of comorbidity in ID and LD in a contemporary EP population, or the underlying neuropsychological profiles of children with isolated versus multiple deficits. Such investigations are important for elucidating the mechanisms underlying academic difficulties, identifying the educational needs of children with different comorbidities and informing the provision of intervention strategies.

In a national, population-based cohort of EP children without neurosensory impairments who were born in the 1990s, we explored the prevalence and comorbidity of ID and LD in both reading and mathematics. The aims of the present study were to (1) describe the rates of ID and LD and explore the extent to which these are comorbid among EP children, (2) explore the neuropsychological profiles of EP children with specific and comorbid disabilities and (3) investigate the impact of specific versus comorbid disabilities on scholastic outcomes.

Given the high risk for poor general cognitive processing observed in this population, we hypothesised that EP children without neurosensory impairments would have significantly higher rates of ID and LD and a greater risk for comorbid ID/LD than children born at term. We also hypothesised that ID and LD would be associated with poor neuropsychological abilities and that EP children with comorbid ID/LD would have the poorest performance on tests of executive function, sensori-motor and visuo-spatial skills and a significantly greater reliance on SEN provision.

Section snippets

Participants

Participants were members of the UK EPICure Study cohort. From 1st March through 31st December 1995, all babies born < 26+ 0 weeks' gestational age and admitted for neonatal intensive care in the whole of the UK and Ireland were identified (n = 811) and surviving children (n = 314) were invited to participate in follow-up assessments. For the first two assessment waves, response rates were 90% (n = 283) at two years of age [25] and 78% (n = 241) at six years of age [26]. Data for the present report relate

Prevalence of learning disabilities

The prevalence and comorbidity of LD are shown in Table 2. In total, 86 (53%) of EP children and 145 (95%) of controls had no disability. Thus adverse outcomes were significantly more common among EP children, with a total of 75 (47%) EP children having either ID or LD compared with 7 (4.6%) controls (RR 10.12; 95% CI 4.81 to 21.27). Fifteen (9%) EP children and 2 (1%) controls had ID alone (RR 12.65; 95% CI 2.82 to 56.67). Adding together those with specific LD (i.e., LD without ID), 22 (14%)

Discussion

In this national cohort study we found that of the 47% of EP children with intellectual or learning deficits, the vast majority had comorbid difficulties, and that half of those with comorbid difficulties had ID, RLD and MLD. Isolated cognitive or learning deficits were therefore uncommon among EP children. This highlights the complex nature of learning difficulties and disabilities following EP birth and the pervasive impact of extreme prematurity across multiple developmental domains.

These

Source of funding

The EPICure Studies were funded by the Medical Research Council (MRC) UK and the work conducted for this manuscript was supported by a project grant from The Nuffield Foundation (EDU/40442). Neil Marlow receives a proportion of funding from the Department of Health’s NIHR Biomedical Research Centres funding scheme at UCLH/UCL. Dr Gilmore is supported by a Royal Society Dorothy Hodgkin Fellowship.

Contributors' statements

Samantha Johnson contributed to study design and management, data collection, wrote the first draft of the manuscript, critically revised it and approved it for submission. Victoria Strauss conducted data analyses, reviewed and critically revised the manuscript and approved it for submission. Camilla Gilmore and Julia Jaekel reviewed and critically revised the manuscript and approved it for submission. Neil Marlow, chief investigator of the EPICure Study, led the study design, management and

Conflict of interest statement

The authors have no conflicts of interest to disclose.

Acknowledgements

The authors are indebted to the EPICure Study Group, which included paediatricians in 276 maternity units in the United Kingdom and Ireland who identified the original cohort, contributed data to the study and whose help was invaluable. We are also indebted to the schools and teachers who supported study assessments throughout this follow-up, and to the many children and parents for their continued participation in the EPICure Studies. Co-investigators for the 11 year evaluation of the cohort

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