Bilingual speakers benefit from protection against cognitive decline in multiple sclerosis

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Bilingual speakers may benefit from protection against cognitive decline in multiple sclerosis according to a new study.

In the first paper of its kind to test the idea that speaking multiple languages protects against decline in brain function, MS patients who were bilinguals scored better than their single language-speaking peers in cognitive tests.

The new research published in Linguistic Approaches to Bilingualism looked at groups of bilingual and monolingual speakers who were being treated for multiple sclerosis.

The team found that the bilingual patients scored similarly to healthy participants, while patients who only had fluency in one language performed worse than the monolingual control.

Lead author Dr Fraibet Aveledo, a lecturer in child language development and bilingualism from the University of Reading said:

“This is the first study that we’re aware of that has tested the idea that there is an advantage for bilinguals when it comes to neurodegenerative diseases such as MS.

“While most studies analyse clinical records of patients with dementia, our study has directly compared four groups of people and reveals a significant cognitive boost for MS patients who speak multiple languages compared to their single language peers.”

Monitoring the benefits

The study took matched groups of bilingual and monolingual MS patients from the Gregorio Marañón Hospital in Madrid and matched them to ensure that measures of cognitive decline were similar.

The subsequent tests examined levels of cognitive ‘monitoring’ relating to attention and the evaluation of behaviour, and the team found that bilingual patients and control groups who didn’t have MS scored similarly on the tests, while there was a significant difference between monolingual patients and their control.

The team found that the bilingual patients scored similarly to healthy participants, while patients who only had fluency in one language performed worse than the monolingual control.

Dr Christos Pliatsikas, an associate professor in psycholinguistics at the University of Reading said:

“The exciting thing about this study is that it demonstrates for the first time that the benefits of bilingualism including having a preventative effect against cognitive decline in MS.”

“Previous studies have provided some clues as to the potential effect of speaking multiple languages on the brain and its power to protect against disease, including increasing the volume of several brain areas that are usually connected to language learning and processing. Now this new study shows how this idea is taking place in practice.”

Improving quality of life

Dra. Yolanda Higueras, a neuropsychologist in Dra. Marisa Martínez-Ginés´ MS Unit at Gregorio Marañón Hospital, commented that:

“People with MS want to work to improve their daily-basis functioning, and studies like this one offer new information about how to build-up their cognitive reserve from early stages. As researchers this collaborative project with Reading University was an excellent opportunity to think about the role that linguistics plays in managing MS.”

Funding: The study was funded by the University of Reading’s Centre for Language and Multilingualism and supported by the Instituto de Investigación Sanitaria Gregorio Marañón (Health Research Institute Gregorio Marañón (IISGM)) who provided access to patients.


Multiple sclerosis (MS) is a chronic and disabling disease of the central nervous system that predominantly affects young adults [1]. In addition to focal demyelinating white matter lesions, MS is characterized by progressive grey matter volume (GMV) loss [2].

The latter occurs early in the disease [3,4] and is closely correlated to cognitive impairment, a prevalent symptom affecting 43–70% of people with MS (pwMS) [57], that has a fundamental impact on health-related quality of life (HRQoL) [8].

While global GMV loss is commonly associated with cognitive impairment in MS [9,10], more recently, regional GMV reduction of distinct cortical areas was linked to frequently affected cognitive domains.

Poor performance in sustained attention and information processing speed was correlated to volume loss in the auditory and premotor cortices [11], in the right inferior longitudinal fasciculus, the right inferior frontal gyrus and the left thalamus [12], and in the posterior cingulate and precuneus, caudate, putamen, and cerebellum [13].

In addition, visual memory impairment was associated with GMV loss of the splenium of the corpus callosum and the left inferior longitudinal fasciculus, while verbal fluency impairment was correlated to volume loss in the right insula and the left postcentral gyrus [13].

In healthy adults, second language (L2) learning was demonstrated to induce neuronal plasticity in language-related brain regions. In experimental training studies, the effect of L2 training over a minimum period of three months was associated with GMV increase of the right hippocampus, the left inferior and middle frontal gyrus and the left anterior temporal pole [1416].

Neuroplasticity following L2 experience in these regions was not solely restricted to better L2 knowledge, but also associated with improvements in basic cognitive processes [17,18]. Cross-sectional studies revealed superior performance in memory and executive tasks of early and experienced bilinguals when compared to monolinguals [19,20].

Further, bilinguals were shown to exhibit a delay in the onset of dementia symptoms by four years compared to monolinguals [21], an observation that supports L2 learning as a training strategy for healthy cognitive aging [17]. However, whether L2 training has also the capability to induce advantageous effects on brain plasticity in pwMS has not been investigated so far.

In this explorative, prospective longitudinal study we aimed at clarifying (1) whether short L2 training induces similar brain plasticity in language-specific areas in pwMS and HCs; (2) whether pwMS are able to acquire a L2 as efficiently as age- and sex-matched healthy controls; and, (3) whether a potentially motivating activity like L2 learning improves HRQoL in pwMS.


Source:
University of Reading

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