Multilingual experience modulates resting-state functional connectivity and executive functioning in cognitive aging

Abstract

Bi-/multilingualism has been found to act favourably on the cognitive aging (CA) trajectory due to the increased executive functioning demands that dual-language use exerts on the brain leading to contributions to neurocognitive reserve and resilience. There is a gap in the literature on how individual differences in the degree of multilingualism influence this trajectory. Furthermore, other lifestyle factors such as diet and exercise, have also been shown to influence CA, yet language experiences and lifestyle factors have rarely been examined together. This thesis aims to fill this gap by examining the unique influence of multilingual language engagement on intrinsic brain activity at-rest and working memory performance. A comprehensive language and lifestyle profile was calculated from native Norwegian multilingual speakers with English as one of their additional languages (n=90, mage=49,3, (SD=18.06), range 19-82. Resting-state Electroencephalography (rs-EEG) and working memory were assessed and regressed against a continuous measure of multilingualism (MLD) while controlling for other lifestyle-experiences. Results indicate a near-significant trend hinting that degree of multilingualism offsets the downwards aging trajectory of EEG coherence in alpha and gamma coherence across several electrode regions. A significant positive interaction between age and MLD was found for WM performance. An exploratory post-hoc analysis revealed a null relationship between functional connectivity and working memory. Results suggest that a higher degree of multilingualism leads to increased resilience against CA.