Bilingualism and the severity of poststroke aphasia

Abstract

Background: Bilingualism has been associated with cognitive benefits in healthy people as well as in patients with cognitive impairment due to stroke and dementia. However, the relationship between bilingualism and aphasia is more complex. While bilinguals are as likely as monolinguals to develop aphasia after stroke, studies of relationship between bilingualism and severity of poststroke language recovery are few and have produced conflicting results, with much evidence derived from immigrant populations or small case series. Aims: Against this background of limited number of studies, we set out to explore the relationship between bilingualism and severity of language impairment in stroke aphasia. We explored the hypothesis that enhanced cognitive abilities related to bilingualism may have a positive impact on recovery from aphasia. Methods & Procedures: We investigated 38 bilingual and 27 monolingual patients who participated in a longitudinal hospital-based stroke registry and were evaluated at least 3 months after stroke (mean 11.5 months). Patient performance on language and other cognitive functions was evaluated with Addenbrooke's Cognitive Examination-Revised (ACE-R) validated for use in aphasia in local languages and for varying educational levels. The results of monolinguals and bilinguals were compared after accounting for confounding variables, including age, gender, education, occupation, medical, and stroke characteristics. Outcomes & Results: Aphasia severity as measured by the language domain sub-scores (total of language and fluency scores) of ACE-R was significantly higher in monolinguals compared with bilinguals (7.0 vs. 14.4, maximum score 40; p = 0.008, effect size = −0.691). Bilinguals performed significantly better than their monolingual counterparts in attention, memory, and visuospatial domains of ACE-R. A univariate general linear model analysis showed that bilingualism was significantly associated with higher language domain scores of ACE-R after adjusting for other confounding variables. Conclusions: The results suggest that although bilingual speakers are at equal risk of developing aphasia after stroke as monolingual ones, their aphasia is likely to be less severe.

The Many Shades of Bilingualism: Language Experiences Modulate Adaptations in Brain Structure

“…It even seems to be the case that bilingualism‐induced neural efficiency may prove beneficial in cases of acute neural tissue loss. Significantly more bilinguals than monolinguals report intact cognitive functions following a stroke (Alladi et al., ) and bilingual individuals experience less severe post‐stroke aphasia (Paplikar et al., ). These results have been interpreted as evidence for faster, more efficient, rewiring of lost connections and adapting to a new situation following sudden onset brain damage.…”

A Bilingual Advantage? An Appeal for a Change in Perspective and Recommendations for Future Research

“…It has been suggested that continuously speaking two languages might affect language control systems located at prefrontal cortices and therefore protect brain areas that are most vulnerable to aging. Possibly the most impressive are the findings that suggest that bilingualism delays the onset of dementia [65,66], and that it leads to a better cognitive outcome after stroke [67,68]. However, as with the cognitive benefit as such, not all studies have found this specific benefit, especially prospective studies that followed healthy adults in contrast to retrospective studies that investigated the onset of dementia in dementia patients (for recent review, see [69]).…”

Beyond Alzheimer’s Disease: Bilingualism and Other Types of Neurodegeneration

“…However, akin to the studies reviewed herein, they predict better clinical outcomes, due to hypothesized bolstered neural and/or cognitive reserves. Most prominently, it is reported that bilingualism is a predictive factor for improved post-stroke cognitive outcomes (Alladi et al, 2016), as well as less severe expression of post-stroke aphasia symptoms (Paplikar et al, 2018). These preliminary results suggest neurocognitive effects of bilingualism even in scenarios of non-progressive neurodegeneration and opens up research avenues encompassing an increasingly wider scope on interactions between bilingualism and neurological conditions.…”