Lebel, CatherineKar, Preeti2021-09-282021-09-282021-09Kar, P. (2021). Early Influences on brain development in preschool children (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.http://hdl.handle.net/1880/113975During early childhood, extensive brain development takes place which underlies foundational cognitive and behavioural learning. Early environmental factors during the prenatal period and first few postnatal years can play important roles in promoting or hindering this period of brain development. Breastfeeding in infancy and alcohol use in pregnancy are both maternal behaviors with long-term impacts on children, but their downstream effects on the brain are not well-understood during early childhood. My thesis used diffusion tensor imaging to assess white matter development in young children (2-7 years) in association with 1) breastfeeding exclusivity status at 6 months of age and the total duration of any breastfeeding, as well as 2) prenatal alcohol exposure (PAE). First, I found that breastfeeding exclusivity and duration were associated with global and regional white matter microstructure, even after controlling for perinatal and sociodemographic factors, and these findings differed by sex. Second, I found that young children with PAE showed altered white matter microstructure cross-sectionally and longitudinally compared to unexposed controls. Third, measures of white matter in motor tracts were associated with motor performance in unexposed typically developing children, but these structure-function associations were not present in young children with PAE. This work highlights the dynamic and complex brain development taking place in early childhood and indicates how environmental variables during the prenatal and postnatal period, such as breastfeeding and PAE, moderate brain circuitry and behaviors in young children. This research has broad implications for clinical, policy, and health education strategies to promote breastfeeding and prevent PAE and ultimately support mothers and children.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.MRIprenatal alcohol exposurepediatricmotorbrain developmentwhite matter developmentdiffusion tensor imagingEducation--Early ChildhoodNeuroscienceRadiologyPsychology--DevelopmentalPsychobiologydoctoral thesis10.11575/PRISM/39287