Alterations in Brain Structure and Function in Children With Fetal Alcohol Spectrum Disorder

Abstract

Fetal Alcohol Spectrum Disorder (FASD) can occur when a mother drinks alcohol during pregnancy. The full spectrum of adverse effects on the brain induced by prenatal alcohol exposure ranges from mild to severe brain dysfunction in executive functions, learning, memory, social communication, and sensory-motor skills. The goals of this thesis were to assess the functional outcomes of children with FASD using psychometric testing and eye movement control tasks and relate these to measures obtained from diffusion tensor imaging (DTI). Results from the eye movement studies successfully differentiated those with FASD from controls on both sensory-motor and behavioural outcomes. Children with FASD showed deficits in response inhibition, working memory, saccadic reaction time, and saccade metrics on three eye movement tasks. A sexually dimorphic impact of prenatal alcohol exposure on eye movement control was also found. The psychometric tests revealed deficits in set shifting, response inhibition, selective and sustained attention, working memory, and visuospatial processing. The DTI results revealed significantly higher mean diffusivity in the splenium of the corpus callosum. These measures were then correlated to one another to search for common brain pathways utilized to complete these tasks. Working memory measures obtained from the memory-guided eye movement task significantly correlated with three psychometric tests which measured working memory in the FASD group. The prosaccade eye movement task which measures basic sensory-motor processing was also correlated with a visuospatial processing psychometric task in the FASD group. Finally, response inhibition measures from the eye movement tasks correlated with response inhibition measures obtained from the psychometric testing in the FASD group. Additionally, eye movement inhibition measures correlated negatively to fractional anisotropy and positively to mean diffusivity of the splenium in the control, but not the FASD group. Therefore, brain function of typically developing controls and children with FASD can be successfully assessed using eye movement tasks, psychometric testing and DTI. These functional measures help identify specific brain regions affected by prenatal alcohol exposure which can lead to more specific interventions. These findings can also help streamline the diagnostic process by pointing to efficient and effective tools that differentiates children with FASD from controls.