Abstract
Magnetic resonance imaging (MRI) is an indispensable tool for investigating brain development in young children and the neurobiological mechanisms underlying developmental risk and resilience. Sub-Saharan Africa has the highest proportion of children at risk of developmental delay worldwide, yet in this region there is very limited neuroimaging research focusing on the neurobiology of such impairment. Furthermore, paediatric MRI imaging is challenging in any setting due to motion sensitivity. Although sedation and anesthesia are routinely used in clinical practice to minimise movement in young children, this may not be ethical in the context of research. Our study aimed to investigate the feasibility of paediatric multimodal MRI at age 2–3 years without sedation, and to explore the relationship between cortical structure and neurocognitive development at this understudied age in a sub-Saharan African setting. A total of 239 children from the Drakenstein Child Health Study, a large observational South African birth cohort, were recruited for neuroimaging at 2–3 years of age. Scans were conducted during natural sleep utilising locally developed techniques. T1-MEMPRAGE and T2-weighted structural imaging, resting state functional MRI, diffusion tensor imaging and magnetic resonance spectroscopy sequences were included. Child neurodevelopment was assessed using the Bayley-III Scales of Infant and Toddler Development. Following 23 pilot scans, 216 children underwent scanning and T1-weighted images were obtained from 167/216 (77%) of children (median age 34.8 months). Furthermore, we found cortical surface area and thickness within frontal regions were associated with cognitive development, and in temporal and frontal regions with language development (beta coefficient ≥0.20). Overall, we demonstrate the feasibility of carrying out a neuroimaging study of young children during natural sleep in sub-Saharan Africa. Our findings indicate that dynamic morphological changes in heteromodal association regions are associated with cognitive and language development at this young age. These proof-of-concept analyses suggest similar links between the brain and cognition as prior literature from high income countries, enhancing understanding of the interplay between cortical structure and function during brain maturation.
Highlights
The first three years of life represent the most extensive period of brain growth and synapse development, where critical neural pathway development and network maturation occur (Hermoye et al, 2006; Ouyang et al, 2019; Knickmeyer et al, 2008)
A total of 239 children attended for imaging at 2–3 years; 23/239 (9.6%) for the pilot at Tygerberg CUBIC, and 216/239 (90.4%) for the main neuroimaging study to Groote Schuur CUBIC (Fig. 1)
A greater proportion of children in the neuroimaging sub-group were in the middle income category (Supplementary Tables 1 and 2)
Summary
The first three years of life represent the most extensive period of brain growth and synapse development, where critical neural pathway development and network maturation occur (Hermoye et al, 2006; Ouyang et al, 2019; Knickmeyer et al, 2008). The United Nations Sustainable Development Goals (SDGs, https://sustainabledevelopment.un.org) have focused the world on the importance of children thriving; 43% of children under 5 years are at risk of failing to reach their developmental potential worldwide. The majority of these children live in low and middle-income countries (LMIC); sub-Saharan Africa (SSA) has the highest proportion of children at risk of developmental delay (Black et al, 2017). MRI studies of young children in LMICs are lacking (Azhari et al, 2019) and very little research has been performed to assess the link between early brain structure and cognitive development in SSA (Paterson et al, 2006)
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