Effects of gestational thyroid hormone exposure: insights into neurodevelopment using MRI

Scholz, Anna 2024. Effects of gestational thyroid hormone exposure: insights into neurodevelopment using MRI. MD Thesis, Cardiff University. Item availability restricted.

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Abstract

Introduction: Children exposed to gestational thyroid abnormalities may face an increased risk of adverse neurodevelopmental outcomes. Aim: To investigate if abnormal maternal thyroid hormone (TH) bioavailability in utero affects child brain development as assessed with neuroimaging. Methods: A systematic review was conducted to identify MRI neuroimaging studies of participants exposed to thyroid function abnormalities in utero or during childhood. The Controlled Antenatal Thyroid Screening (CATS) III study follows a subset from the original CATS study cohort, a randomised controlled trial examining effects of maternal gestational thyroid function (GTF) on offspring development. A total of 85 children aged 11 to 16 underwent T1-weighted structural MRI. Participants were divided into groups: untreated suboptimal GTF (SGTF)(n=21), normal GTF (n=24), optimally treated SGTF (n=20), and overtreated SGTF (n=20). The primary outcome examined the association of SGTF and its treatment with global brain volumes. Secondary outcomes investigated the association of maternal thyrotropin (TSH) and free thyroxine (fT4) levels with brain volumes. Results: The systematic review included 22 studies on maternal thyroid dysfunction (MTDF) during pregnancy, congenital hypothyroidism (CH), and transient hypothyroxinemia of prematurity (THOP). The heterogeneity in study design made it difficult to extrapolate or combine findings with confidence. The foetal brain appears to be most sensitive to thyroid abnormalities in the first trimester, but CH and THOP studies also indicated long-term impacts on brain morphology. TSH had the most consistent association with reported differences The CATS III study found no significant effect of treating mild maternal thyroid dysfunction on brain morphology at a macrostructural level. A weak correlation between first trimester maternal TSH levels and several grey matter regional volumes was noted but did not remain significant after correction for multiple testing. Conclusion: Macrostructural neuroimaging results of the effect of mild gestational thyroid function abnormalities are often weak and conflicting. Other MRI modalities are the next step to investigate potential microstructural effects of thyroid function on brain development.

Item Type:	Thesis (MD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Medicine
Date of First Compliant Deposit:	27 March 2025
Last Modified:	11 Apr 2025 09:21
URI:	https://orca.cardiff.ac.uk/id/eprint/177213

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