Project Summary/Abstract
Society at large is facing a global “dementia epidemic” that is predicted to intensify with the growing aging
population. Although there is currently no cure for this devastating and pervasive condition, one life experience
shown to protect against the onset of Alzheimer’s disease and related disorders (ADRD) is that of bilingualism.
Nevertheless, findings regarding bilingualism as a contributor to cognitive reserve are mixed. These mixed
findings may, in part, be attributed to variability in the characterization of the bilingual experience across distinct
sociocultural contexts in addition to the presence of potential confounding variables. Little attention has been
directed towards examining bilingualism factors (e.g., language dominance, proficiency, use and age of
acquisition) that may underly these findings. In addition, limited attention has been directed towards language-
prominent dementia syndromes, such as primary progressive aphasia (PPA). Although speech and language
impairments are ubiquitous features of ADRD, in the case PPA these debilitating deficits manifest as initial,
predominant symptoms. Differential patterns of language decline have been observed in bilingual PPA, with
resilience of the first learned language and parallel decline reported in the literature. However, a nuanced account
establishing patterns of language decline across different linguistic domains has yet to be systematically
examined in PPA. In addition, although positive effects of speech-language intervention are now well
documented in monolingual speakers with PPA, there is a significant gap in the literature examining treatment
optimized for bilingual speakers with PPA. Moreover, the behavioral, neural and bilingual factors associated with
language re-learning have yet to be established in bilingual speakers with PPA. The overall aim of the proposed
research is to establish associations between bilingualism factors and the onset, decline, and treatment response
of Hispanic, bilinguals (Spanish-Catalan) with PPA. In Aim 1, we seek to identify bilingualism factors associated
with a later age of onset in Hispanics with each PPA variant. In Aim 2, we seek to identify the bilingualism factors
associated with differential patterns of language impairment in Hispanics with PPA using metrics derived from
connected speech. In Aim 3, we will evaluate the benefits of tailored speech-language intervention in the largest
behavioral rehabilitation study of bilingual Hispanics with PPA to-date. We will also identify the bilingualism
factors, pre-treatment cognitive-linguistic measures, and brain regions implicated in bilingualism that predict the
magnitude of within-language gains and cross-language transfer effects. In order to accomplish these aims, we
will enroll 90 Hispanic, bilinguals with PPA who will undergo behavioral assessment, MRI, and speech-language
treatment. This proposal will provide needed evidence regarding cognitive reserve and linguistic resilience by
leveraging a large bilingual PPA cohort via an established international collaboration. Outcomes will also provide
crucial knowledge regarding neural mechanisms of language re-learning and will address how specific bilingual
factors influence cognitive reserve and linguistic resilience in language-prominent dementia.
