Two independent lines of research provide evidence that speaking more than one language may 1) contribute to increased grey matter in healthy younger and older adults and 2) delay cognitive symptoms in mild cognitive impairment (MCI) or Alzheimer disease (AD). We examined cortical thickness and tissue density in monolingual and multilingual MCI and AD patients matched (within Diagnosis Groups) on demographic and cognitive variables. In medial temporal disease-related (DR) areas, we found higher tissue density in multilingual MCIs versus monolingual MCIs, but similar or lower tissue density in multilingual AD versus monolingual AD, a pattern consistent with cognitive reserve in AD. In areas related to language and cognitive control (LCC), both multilingual MCI and AD patients had thicker cortex than the monolinguals. Results were largely replicated in our native-born Canadian MCI participants, ruling out immigration as a potential confound. Finally, multilingual patients showed a correlation between cortical thickness in LCC regions and performance on episodic memory tasks. Given that multilinguals and monolinguals were matched on memory functioning, this suggests that increased gray matter in these regions may provide support to memory functioning. Our results suggest that being multilingual may contribute to increased gray matter in LCC areas and may also delay the cognitive effects of disease-related atrophy.
The current study explored whether education, a proxy of cognitive reserve, modifies the association between episodic memory performance and βeta-amyloid load (Aβ), a biomarker of Alzheimer’s disease, in a cohort of cognitively normal elderly adults. One hundred and four participants (mean age 73.3 years) evenly spread out in three bands of education were recruited. Participants underwent neuropsychological assessment, structural MRI as well as PET imaging to quantify Aβ load. Moderation analyses and the Johnson-Neyman technique were carried out to examine the interaction of education with Aβ load to predict episodic memory performance. Linear regressions were then performed within each group of education to better illustrate the interaction effect (all analyses were controlled for age and sex). The interaction between education and Aβ load was significant (p<0.05) for years of education, reaching a cut-off point of 13.5 years, above which the relationship between Aβ load and episodic memory was no longer significant. Similarly, significant associations were found between Aβ and episodic memory among participants with secondary (p<0.01) and pre-university education (p<0.01), but not with a university degree (p=0.253). Episodic memory performance is associated with Aβ load in cognitively normal elderly individuals, and this relationship is moderated by educational attainment.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.