Poster D62, Friday, August 17, 4:45 – 6:30 pm, Room 2000AB

Beyond dementia: interaction of bilingualism and neurodegeneration

Toms Voits1, Holly Robson1, Jason Rothman1, Christos Pliatsikas1;1University of Reading

The potential for beneficial consequences of bilingualism on cognition and the brain has been an increasingly debated topic for the past few years. While positive outcomes associated with speaking two or more languages have been widely studied in healthy adult populations (see Lehtonen, 2018, for a review), the literature on bilingualism and the declining brain is much more scarce. In fact, most of the studies within this body of literature are focussed on healthy ageing populations and people with dementia. In these groups several positive effects of bilingualism have been documented, particularly potential neuroprotective effects in healthy populations (Luk et al., 2011), the preservation of cognitive abilities in bilinguals with brain deterioration (Gold et al., 2013), better structural integrity of the brain in bilingual individuals diagnosed with Alzheimer’s Disease and Mild Cognitive Impairment (Duncan et al., 2018), and the delay in the onset of dementia symptoms (Alladi et al., 2013). However, not all studies find support for these claims (e.g. Zahodne, 2014). While dementia is the most commonly studied neurological disorder in the context of bilingualism research, studies on interaction between bilingualism and other neurological disorders that lead to the loss of neural tissue, such as Huntington’s disease, Parkinson’s disease, multiple sclerosis, schizophrenia, psychosis, primary progressive aphasia etc., remain more limited and fragmented. With some exceptions, literature is mostly focused on the effects that age- or disease-related neurodegeneration has on one’s languages and associated executive control and not the effects bilingualism may have on the progress of neurodegeneration. Moreover, and although bilingualism is suggested to be beneficial in progressive neurodegeneration, recent evidence has also suggested bilingualism to be factor that predicts enhanced cognitive improvement in individuals who have suffered stroke (Alladi et al., 2016). These results imply potential benefits of bilingualism even on the recovery of patients with acute neural tissue loss, and further open up research avenues encompassing an increasingly wider scope on interactions between bilingualism and neurological conditions. The last comprehensive review on the topic (Paradis, 2008), was published a decade ago, and even so, the focus was on understanding how neurological disorders impair language processing in bilinguals, but not on the effects bilingualism might have on cognition and brain structure. Given the now proposed neuroprotective effects of bilingualism, it is important and timely to re-examine the literature through a new lens . We provide a focused literature review summarizing the available evidence on progressive neurological disorders and stroke in bilinguals and examines whether there are any bilingualism-related effects on the cognition or brain structure and function of these patients. In doing so, we aim to capture the state of the art in bilingualism research of the declining brain and associated disorders, identify the gaps, and suggest the most feasible avenues to fill them in future research.

Topic Area: Multilingualism

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