Cognitive reserve: Evaluating the relationship between WASI‐II Matrix Reasoning and tau accumulation using [18F]MK6240 in monolingual and bilingual individuals

Abstract

AbstractBackgroundCognitive reserve (CR), a protective mechanism, allows for sustained cognitive functioning in older adults with greater experiential resources. Bilingualism, an indicator of greater cognitive reserve, has been found to preserve cognitive performance in older adults despite significant disease pathology. While the association with amyloid has been well acknowledged, the effect of tau is still under investigation. In the present study, we aim to evaluate the effect of bilingualism on individuals’ cognition and tau load.MethodThis study was conducted in 331 individuals (213 cognitively unimpaired (CU)) and 116 cognitively impaired (CI; 81 MCI and 35 AD) from the TRIAD cohort. 40% of the study participants were monolingual. Wechsler Abbreviated Scale of Intelligence ‐ Second Edition (WASI‐II) was used to measure cognitive ability and reasoning in individuals. Accumulation of tau was assessed with [18F]MK6240 PET and standardized uptake value ratio (SUVRs) were calculated between 90 to 110 min post‐injection, using cerebellum grey matter as the reference region. A voxel‐based regression model evaluated the relationship between the WASI‐II score and the PET markers [18F]MK6240, correcting for age, sex, education, APOE, diagnosis and RFT was used to account for multiple comparisons.ResultOur data showed that bilingual individuals demonstrated significantly higher scores on the Wechsler Abbreviated Scale of Intelligence ‐ Second Edition (WASI‐II) in comparison to monolingual individuals. A negative association between the cognitive score and tau accumulation was found in both monolingual and bilingual groupings. In the bilingual individuals, the associated regions were precuneus area, medial and lateral lobes. In the monolingual group, the associated regions were right frontal lobe, parietal lobe and cuneus areas.ConclusionOur results demonstrate that bilingual individuals are more resilient to the accumulation of tau; shown in higher scores in cognitive ability and reasoning despite having more regions affected than their monolingual counterparts.