Language Outcomes in Bilingual Individuals with Dementia
Creators: name: Billinger, Morgan
name: Messinger, Abigail
name: Dwyer, Tyler
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2017

description: Purpose or Research Questions: In people with dementia, how does being bilingual influence the manifestation of dementia related to language skills? Background: Language loss is a paramount component of dementia, and in the case of bilingual speakers, declines in language functioning can occur predominantly in the first language (L1) or in all languages spoken. However, the literature is mixed with regard to whether the two languages decline in tandem or differentially [i.e., one language declines more than the other(s)] (Nanchen et. al, 2016; Ivanova et. al, 2014; Stilwell et. al, 2016). Thus, the present study reviewed the literature in order to (1) determine the nature of the loss in one or more languages in bi- or multilingual individuals with dementia, and (2) to describe the characteristics of that decline with regard to various language domains, including verbal fluency, code-switching, and pragmatic usage, among others. Methods: Researchers utilized six databases to electronically search for articles that met inclusion criteria in February 2017. The initial searches yielded 227 articles after deduplication. The researchers utilized the following inclusion criteria: (1) bilingual or multilingual adult participants, diagnosed with any form of probable dementia; (2) studies including language outcomes (L1/L2 and dominant/non-dominant); (3) studies published in English; (4) study designs comprised of randomized control trials, cohort studies, case studies, systematic reviews, cross-sectional studies, case-control studies, non-randomized control trials, and meta-analyses. Researchers first independently completed title and abstract reviews yielding 61 articles to move to the next round for full-text reviews. Researchers then independently completed full text reviews yielding 15 articles for final inclusion. Anticipated Results: Fifteen studies were included to explore the language outcomes of bilingual and multilingual adults diagnosed with probable dementia of any form. A large majority of studies (n=9), concluded parallel deterioration of all languages spoken by participants. From the included studies, we noted multiple factors reported by the researchers accounting for the parallel or nonparallel deterioration of languages: (1) age of acquisition, (2) proficiency or dominance, (3) and frequency of use. Language declines in each language were also reported to vary longitudinally. Discussion: A review of the literature yielded a complex and, at times, inconclusive picture of the language outcomes in bilingual individuals with dementia. Studies reported contradicting findings as to whether languages declined simultaneously or asynchronously (Salvatierra et. al, 2007; Kowoll et. al, 2015). Our preliminary findings were consistent with the conclusions of a similar systematic review completed by Stilwell et. al in 2016, regarding language outcomes more specifically in patients with probable Alzheimer's disease, a form of dementia. Further research into the language outcomes of bilingual and multilingual adults with dementia will allow for a better understanding of the progression of their language decline due to neurodegenerative disease.