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

The 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. Using 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. Bilinguals 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. Patterns 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. 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 Aβ42/40.