PhD Oral Exam - Kristina Coulter, Psychology

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

Being bilingual is hypothesized to lead to greater brain resilience in aging and Alzheimer’s disease (AD), allowing for greater cognitive outcomes in the context of brain aging and neuropathology. However, the relationship between bilingualism and brain resilience (i.e., structural brain changes reflecting brain reserve and functional brain changes reflecting cognitive reserve) remains poorly understood. This thesis examined differences in brain structure and function between monolingual and bilingual older adults with or at risk for AD using data from the Comprehensive Assessment of Neurodegeneration and Dementia Study and the Consortium for the Early Identification of Alzheimer’s disease – Quebec. Study I examined structural brain differences in AD-related and language-related brain areas between monolingual and bilingual older adults with or at-risk for AD. I found greater hippocampal volume, providing evidence of greater brain reserve and brain maintenance in an AD-related brain area, for bilinguals compared to monolinguals with AD. Study II used resting-state fMRI methods to examine differences in default mode network functional connectivity between monolingual and bilingual older adults with or at-risk for AD. I found lower default mode network connectivity, providing evidence of greater cognitive reserve, for bilinguals compared to monolinguals with AD. This thesis provides evidence of brain and cognitive reserve related to bilingualism, providing support for bilingualism as a life factor that contributes to greater brain resilience in AD. By using structural and functional brain measures across the full spectrum of AD development, this thesis makes a significant contribution to the literature on bilingualism and brain resilience in aging.