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

Abstract

AbstractBackgroundAlthough bilingualism has been associated with cognitive reserve and a later age of dementia onset (e.g., Alladi et al., 2013, 2017; Bialystok et al., 2007, 2010; de Leon et al., 2020), the effects of bilingualism on neuropsychological test performance in bilinguals with and without cognitive impairment have not yet been thoroughly investigated (e.g., Briceño et al., 2021; Cherner et al., 2021; Padilla et al., 2016).MethodThe present study explored patterns of cognitive performance and impairment across a large sample of bilingual and monolingual Latino older adults from the Health and Aging Brain: Health Disparities cohort (O’Bryant et al., 2021). In addition to examining differences between bilinguals and monolinguals, the associations between specific bilingual factors (i.e., dominance and age of acquisition) and cognitive performance were examined in order to elucidate which components of the bilingual experience explain such associations.ResultBilingual speakers demonstrated a pattern of cognitive resiliency in the form of better performance on attention/processing speed that can be observed across the cognitively unimpaired (Trails A, p = .001; Trails B, p = .02; Digit Substitution p = .004, and Logical Memory I p = .04) and mild cognitive impairment (Trails A, p < .001 and Digit Substitution, p < .02) diagnostic spectrum. In contrast, bilingual speakers demonstrated a pattern of cognitive vulnerability in the form of poorer performance and higher rates of impairment on a language measure that is only evident in the MCI phase (letter fluency, p = .001). Follow‐up analyses revealed bilinguals that 1) had a later age of language acquisition or 2) unbalanced language dominance performed more poorly on cognitive testing (Table 1) and had higher rates of impairment (Table 2). Exploratory analyses revealed that bilinguals with impaired language scores demonstrated lower levels of plasma Ab 42/40 relative (indicative of greater AD pathology) to unimpaired bilinguals (p = .02; Figure 1).ConclusionResults suggest that patterns of cognitive performance and impairment differ as a function of bilingualism. Bilingual factors must be considered in clinical and research investigations centered on evaluating cognitive outcomes of Latino older adults.