Bilingual neurocognitive resiliency, vulnerability, and Alzheimer's disease biomarker correlates in Latino older adults enrolled in the Health and Aging Brain Study ‐ Health Disparities (HABS‐HD)

Abstract

INTRODUCTIONThe effects of bilingualism on neuropsychological test performance in bilinguals with and without cognitive impairment are not well‐understood and are relatively limited by small sample sizes of Latinos.METHODSUsing analysis of covariance (ANCOVA), we explored patterns of cognitive performance and impairment across a large sample of community‐dwelling bilingual and monolingual Latino older adults with (n = 180) and without (n = 643) mild cognitive impairment (MCI) enrolled in HABS‐HD.RESULTSBilinguals demonstrated cognitive resiliency in the form of significantly better performance on the Trail Making Test and Digit Symbol Substitution Test, observed across the cognitively unimpaired and MCI groups. In contrast, bilinguals demonstrated cognitive vulnerability in the form of significantly poorer performance and higher impairment rates on phonemic fluency in the MCI phase, only. Follow‐up analyses revealed less balanced bilinguals demonstrated poorer performance and higher impairment rates on this measure, supported by lower levels of plasma Aβ 42/40.DISCUSSIONPatterns of cognitive performance and impairment differ as a function of bilingualism. Bilingualism must be considered when evaluating cognitive and biomarker outcomes in Latino older adults.Highlights Latino bilinguals perform better on measures of processing speed and coding. Latino bilinguals with MCI demonstrate cognitive vulnerability in verbal fluency. Less balanced bilinguals demonstrate greatest vulnerability anchored by Aβ 42/40.

Bilingualism reduces associations between cognition and the brain at baseline, but does not show evidence of cognitive reserve over time

“…There is evidence suggesting that bilingualism may help individuals maintain cognition against the consequences of brain aging and consequential dementia neuropathology (Abutalebi et al, 2014;Anderson et al, 2018Anderson et al, , 2021Berkes et al, 2021;Costa & Sebastián-Gallés, 2014;Gallo et al, 2020;Gold et al, 2013;Grasso et al, 2023;Li et al, 2017;Olsen et al, 2015;Schroeder & Marian, 2012). Research has shown that bilingual older adults who progress to impairment reach the clinical threshold for diagnosis of Alzheimer's Disease approximately 4.5 years later than comparable monolinguals (Craik et al, 2010;Gollan et al, 2011).…”