Bilingualism Appears to be Protective Against Cognitive Decline Related to Amyloid Burden in Mexican Americans: An HABS‐HD Study

Abstract

AbstractBackgroundBilingualism has been considered to exert protective effects from neurodegeneration and age‐related diseases such as Alzheimer’s Disease (AD). The protective effect is considered to be due to differences in grey and white matter between monolingual and bilinguals; however, no work to date has looked at differences in additional AD brain pathology. The aim of this study was to fill this gap and examine among Mexican Americans the impact of amyloid burden on cognitive functioning stratified by language status.MethodData were analyzed on n = 111 Mexican Americans (n = 45 Monolingual; n = 66 Bilingual) participants from a study of health disparities. All participants underwent cognitive testing and PET amyloid imaging, which was conducted using a Siemens Biograph Vision 450 PET/CT scanner with florbetaben. SUVR regions of interest (ROIs) included Frontal, Anterior/Posterior Cingulate, Lateral Parietal, and Lateral Temporal cortex and were derived using the cerebellum as a reference region in FreeSurfer. Linear regressions were conducted with each ROI included as a predictor variable and cognitive functioning as the outcome variable. Covariates included age, sex, and education. Analyses were split by language status (monolingual, bilingual).ResultAmong monolingual Mexican Americans, higher Global and Lateral Temporal SUVR were significantly related to poorer performance across measures of executive functioning (p = 0.039 and p = 0.038) and processing speed (p = 0.013 and p = 0.027); Global SUVR showed a trend towards significance on a measure of verbal fluency (p = 0.052). In the same group, Frontal SUVR was significant related to poorer performance across measures of global cognition (p = 0.046), executive functioning (p = 0.015), processing speed (p = 0.007) and verbal fluency (p = 0.037), the latter two were also significantly related to Anterior/Posterior Cingulate SUVR (p = 0.008 and p = 0.029). In addition, higher Lateral Parietal SUVR was significantly related to poorer performance on a measure of processing speed (p = 0.030). Among bilingual Mexican Americans, Frontal and Anterior/Posterior Cingulate SUVR were positively associated with semantic fluency (p = 0.049 and p = 0.043).ConclusionAmyloid burden was found to be related to poorer cognitive functioning across multiple domains specifically among monolinguals. Those who identified as bilingual did not present with the same relationship between amyloid uptake and cognitive functioning further supporting the potential protective effect of bilingualism.