Preterm birth as a determinant of neurodevelopment and cognition in children: mechanisms and causal evidence

Lead Research Organisation: University of Edinburgh
Department Name: MRC Centre for Reproductive Health

Abstract

Globally, 15 million infants are born preterm (less than 37 weeks of gestation) each year. Survival rates for infants born too soon or too small have improved dramatically over the past two decades, but brain injury among survivors has not. Consequently, preterm birth is a leading cause of developmental and learning problems in childhood. As survivors of modern intensive care have begun to reach adulthood, it is clear that the legacy of preterm birth can affect the life course. Cerebral palsy, autism, attention deficit hyperactivity disorder, low IQ, memory problems, language and social difficulties, depression, and schizophrenia are all more common in people who were born early.

Importantly, there are no effective treatments for promoting brain health after preterm birth. One of the biggest challenges facing perinatal medicine is to find new ways to reduce brain injury and improve life-long outcomes. In this project, we aim to discover which parental/infant factors influence the brain development of preterm infants, and how those factors become biologically 'embedded' in the brain.

To do this, we will study a large UK-wide population to determine which aspects of being born preterm impact neurodevelopment and ability at school age, and whether a person's socioeconomic circumstances modify these impacts. This will help us define the relative importance of a range of risk/resilience factors to real-world neurodevelopmental outcomes and school performance.

We will use sophisticated brain scans (MRI) to define changes in brain growth that commonly affect premature babies and will use these to investigate how premature birth causes altered brain development. We will investigate whether the perinatal stress environment (hypothalamic-pituitary-adrenal axis activity) and/or markers of low-level chronic systemic inflammation (DNA methylation signatures) link risk factors with brain changes on MRI.

To understand how prematurity affects cognition, we will study the brains of 5-year-olds who were born preterm and a comparator group of children born at term using functional MRI. In this technique, children view movie scenes whilst in the MRI scanner, and brain systems that activate in response to cognitive tasks such as social thinking, attention and memory, are revealed. We expect this analysis to determine whether brain networks that underpin specific cognitive abilities are altered in preterm children and whether cognitive capacities are underpinned by alterations in specific or more general cognitive processes. For example, children born preterm often have social difficulties at school age but it is unknown whether this is due to difficulties in reasoning about other people, or because of more general difficulties with language or attention that make social interactions challenging. Functional MRI will help us to tease apart these alternative accounts, which is a necessary first step for designing targeted cognitive training interventions.

In summary, this programme of work will explain why some premature children develop brain injury while others are resilient. It could pave the way to new therapies that promote healthy brain growth and long-term outcomes because the stress response and immune systems are modifiable, and mechanistic understanding of cognitive deficits is essential for developing rational cognitive training strategies.

Technical Summary

Preterm birth (delivery at less than 37 weeks of gestation) affects around 11% of births, globally, and is a leading cause of neurodevelopmental and cognitive impairment with impacts that extend across the life course. We aim to identify the physiological axes that embed biological, psychosocial and socioeconomic preterm birth-associated risk factors in abnormal brain development. We will use epidemiological, neuroinformatic and experimental medicine approaches, and focus on neuroendocrine stress and immune activation. We have two key goals that are addressable now due to recent advances in population-level neonatal data availability and perinatal phenotyping technologies. The first is to determine the weighted contributions of socioeconomic and medical exposures to neurodevelopment and educational attainment in a contemporary UK population of children born preterm. The second is to elucidate the pathways that link multi-dimensional exposures with abnormal brain development by analysing HPA axis activity, immune dysregulation indexed by DNAm proxies of low-level systemic chronic inflammation, and neuroimaging within a prediction framework. We will characterise brain development in terms of connectome complexity, brain age and markers of myelination, and we will use these together with functional MRI to investigate neural substrates of cognitive impairment and reserve in childhood. We will work with survivors and parents with lived experience of preterm birth to ensure our research questions are relevant and to disseminate our findings. Our ambition is to identify targets within neuroendocrine stress and immune pathways that lead to atypical brain development in preterm infants, paving the way for novel neuroprotective intervention and cognitive training strategies.

Publications

10 25 50
 
Title Animation 
Description Co-design with parents a 5-minute animation designed to support recruitment to PRENCOG 
Type Of Art Film/Video/Animation 
Year Produced 2024 
Impact Favourable participant feedback 
URL https://media.ed.ac.uk/media/Prencog_Neonatal/1_9llqdgsd
 
Title Animation 
Description Co-designd with parents an animation designed to explain to child participants data collection at 5 years of age. 
Type Of Art Film/Video/Animation 
Year Produced 2024 
Impact Favourable feedback 
URL https://media.ed.ac.uk/media/PRENCOG_5%20YEAR%20OLD%20APPOINTMENT_ANIMATION/1_akzmmsc4
 
Description Neonatal brain magnetic resonance imaging: clinical indications, acquisition and reporting
Geographic Reach National 
Policy Influence Type Contribution to new or improved professional practice
 
Description Witness to House of Lords select committee
Geographic Reach National 
Policy Influence Type Contribution to a national consultation/review
URL https://committees.parliament.uk/committee/701/preterm-birth-committee
 
Description Acute High Dose Melatonin for Encephalopathy of the Newborn (ACUMEN):Phase I Study
Amount £5,211,597 (GBP)
Funding ID MR/X030067/1 
Organisation Medical Research Council (MRC) 
Sector Public
Country United Kingdom
Start 09/2023 
End 09/2026
 
Description Theirworld Edinburgh Birth Cohort
Amount £300,000 (GBP)
Organisation Theirworld 
Sector Charity/Non Profit
Country United Kingdom
Start 03/2026 
End 03/2028
 
Title Scripts for analysing Neonatal Magnetisation transfer imaging (MTsat) data 
Description A cardinal feature of the encephalopathy of prematurity is dysmaturation of developing white matter and subsequent hypomyelination. Magnetisation transfer imaging (MTI) offers surrogate markers for myelination, including magnetisation transfer ratio (MTR) and magnetisation transfer saturation (MTsat). Using data from 105 neonates, we characterise MTR and MTsat in the developing brain and investigate how these markers are affected by gestational age at scan and preterm birth. We explore correlations of the two measures with fractional anisotropy (FA), radial diffusivity (RD) and T1w/T2w ratio which are commonly used markers of white matter integrity in early life. We used two complementary analysis methods: voxel-wise analysis across the white matter skeleton, and tract-of-interest analysis across 16 major white matter tracts. We found that MTR and MTsat positively correlate with gestational age at scan. Preterm infants at term-equivalent age had lower values of MTsat in the genu and splenium of the corpus callosum, while MTR was higher in central white matter regions, the corticospinal tract and the uncinate fasciculus. Correlations of MTI metrics with other MRI parameters revealed that there were moderate positive correlations between T1w/T2w and MTsat and MTR at voxel level, but at tract level FA had stronger positive correlations with these metrics. RD had the strongest correlations with MTI metrics, particularly with MTsat in major white matter tracts. The observed changes in MTI metrics are consistent with an increase in myelin density during early postnatal life, and lower myelination and cellular/axonal density in preterm infants at term-equivalent age compared to term controls. Furthermore, correlations between MTI-derived features and conventional measures from diffusion MRI provide new understanding about the contribution of myelination to non-specific imaging metrics that are often used to characterise early brain development. 
Type Of Material Improvements to research infrastructure 
Year Produced 2023 
Provided To Others? Yes  
Impact A novel method for myelin sensitive imaging of the developing human brain. 
URL https://git.ecdf.ed.ac.uk/jbrl/neonatal-mtsat
 
Title Theirworld Edinburgh Birth Cohort (TEBC) 
Description A prospective, longitudinal cohort study of preterm and term infants which aims to investigate neuroanatomic variation and adverse outcomes associated with preterm birth, using brain using MRI linked to biosamples and clinical, environmental and neuropsychological data. Includes datasets linked to published manuscripts using TEBC data. Users may request access to a copy of the data by contacting the Principal Investigator or Data Manager named on this page. 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
Impact None yet. 
URL https://www.research.ed.ac.uk/en/datasets/e65499db-2263-4d3c-9335-55ae6d49af2b
 
Description Interview for national news 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact Following a press release by University of Edinburgh, a clinical research fellow gave an interview for Scottish Television (STV) News about a research output (McKinnon et al JAMA Network Open 2023). A piece on the same output was also published in a national newspaper following the press release.
Year(s) Of Engagement Activity 2023
 
Description Patient group workshop 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Study participants or study members
Results and Impact Convened a parent group to co-design research questions and all participant facing materials related to the award. This included creation of two animations designed to support recruitment and retention:

https://media.ed.ac.uk/media/Prencog_Neonatal/1_9llqdgsd
https://media.ed.ac.uk/media/PRENCOG_5%20YEAR%20OLD%20APPOINTMENT_ANIMATION/1_akzmmsc4
Year(s) Of Engagement Activity 2023
URL https://www.ed.ac.uk/centre-reproductive-health/prencog
 
Description Witness to House of Lords select committee on preterm birth 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact Boardman gave evidence about research priorities in preterm birth to a House of Lords select committee on 4th March 2024. The PRENCOG study was discussed during the session. It was live-streamed on parliament TV.
Year(s) Of Engagement Activity 2024
URL https://committees.parliament.uk/committee/701/preterm-birth-committee