Structural Neural Connectivity Correlates of Early Language and Reading Development and Prenatal Alcohol Exposure

Abstract

Reading and language difficulties are common in children and can have long-lasting effects. Studying the brain’s structural connectivity from an early age can provide insight into the roots of reading and language development and may help with early identification and interventions. Prior studies examining the structural neural correlates of language and pre-reading/reading abilities have mainly focused on older, typically developing children. Unfortunately, little research has been done on preschool children, despite this being a critical learning period. Additionally, the effects of adverse early environments such as prenatal alcohol exposure (PAE) on these associations remain unclear. This thesis aimed to gain a better understanding of the associations between brain structural networks and early language and reading abilities in young children, and the impact of PAE on these associations. Brain imaging data were previously collected using diffusion weighted imaging (DWI) in two cohorts of children from Canada and South Africa. Children completed skills assessments. DWI images were processed, and structural connectivity was assessed using graph theory. The associations between early language and structural connectivity, and the effect of PAE on these associations were analyzed. We found that 1) phonological processing skills were associated with connectivity in a network consisting of reading and language regions in preschool aged children, 2) PAE negatively moderated the relationship between pre-reading skills and network measures in preschool aged children, and 3) PAE-related alterations to language abilities and brain-language associations are present during the toddler years. Our findings expand the current literature, supporting the idea that the structural brain correlates of reading and language are present early, and showing that PAE moderates them. These moderation effects imply that reading and language deficits in children with PAE begin early, suggesting that the roots of reading and language (dis)ability are present well before children go to school. This highlights the need for early diagnosis and interventions to support positive outcomes for children. Our findings provide a better understanding of the neural correlates of pre-reading and language from an early age and can lay the groundwork for earlier interventions for reading and language disabilities.