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White matter analysis of the extremely preterm born adult brain
Hassna Irzan1, Erika Molteni2, Michael Hütel2
1Dept. Medical Physics and Biomedical Engineering, University College London, United Kingdom; School of Biomedical Engineering and Imaging Sciences, Kings College London, United Kingdom.
Insights
Extremely preterm adults show intact brain organization but altered white matter connectivity. These long-term brain changes, including reduced white matter integrity, persist from infancy into early adulthood.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Radiology
Background:
- Few studies investigate white matter alterations in extremely preterm individuals beyond infancy.
- Long-term neuroimaging data now allow investigation of structural changes in extremely preterm young adults.
Purpose of the Study:
- To examine white matter hierarchical organization and microstructure in extremely preterm young adults.
- To compare brain structure and connectivity in extremely preterm adults versus full-term peers.
Main Methods:
- Analysis of neuroimaging data from 85 extremely preterm young adults and 53 controls.
- Identification of brain hubs and peripheral regions.
- Assessment of white matter microstructure using Fractional Anisotropy (FA), Mean Diffusivity (MD), Neurite Density Index (NDI), and Orientation Dispersion Index (ODI).
Main Results:
- The hierarchical organization of the extremely preterm adult brain remains intact.
- Significant alterations in white matter connectivity were observed at macro- and microstructural levels.
- Diminished connectivity, reduced FA and NDI, and increased MD were found, suggesting fewer white matter fibers per voxel.
Conclusions:
- White matter abnormalities in extremely preterm individuals persist into early adulthood.
- These alterations are widespread, particularly along pathways connecting deep grey matter, frontal regions, and the cerebellum.
- The findings highlight the lasting impact of premature birth on brain development and connectivity.
Abstract:
The preterm brain has been analysed after birth by a large body of neuroimaging studies; however, few studies have focused on white matter alterations in preterm subjects beyond infancy, especially in individuals born at extremely low gestation age - before 28 completed weeks. Neuroimaging data of extremely preterm young adults are now available to investigate the long-term structural alterations of disrupted neurodevelopment. We examined white matter hierarchical organisation and microstructure in extremely preterm young adults. Specifically, we first identified the putative hubs and peripheral regions in 85 extremely preterm young adults and compared them with 53 socio-economically matched and full-term born peers. Moreover, we analysed Fractional Anisotropy (FA), Mean Diffusivity (MD), Neurite Density Index (NDI), and Orientation Dispersion Index (ODI) of white matter in hubs, peripheral regions, and over the whole brain. Our results suggest that the hierarchical organisation of the extremely preterm adult brain remains intact. However, there is evidence of significant alteration of white matter connectivity at both the macro- and microstructural level, with overall diminished connectivity, reduced FA and NDI, increased MD, and comparable ODI; suggesting that, although the spatial configuration of WM fibres is comparable, there are less WM fibres per voxel. These alterations are found throughout the brain and are more prevalent along the pathways between deep grey matter regions, frontal regions and cerebellum. This work provides evidence that white matter abnormalities associated with the premature exposure to the extrauterine environment not only are present at term equivalent age but persist into early adulthood.
