Bilingualism cuts dementia prevalence in elderly: Study

Bengaluru: A recent paper by Nimhans has provided conclusive evidence that the prevalence of dementia is lower in elderly people living in socio-linguistically diverse societies, frequently speaking two or more languages compared to monolinguals.

Researchers at Nimhans, claim that this is the first such study conducted in the state, that provides community evidence of the protective effects of lifelong bilingualism on both dementia and mild cognitive impairment (MCI) – which is the transitional phase between normal ageing and dementia.

While several past global and Indian studies have explored how active bilingualism delayed the onset of dementia, they were largely conducted in clinical settings.

This delay is attributed to improved brain executive function, efficient use of neural resources and better neural connectivity due to lifelong use of two or more languages.

A team of 13 research students from the departments of Neurology, Speech Pathology and Audiology, Biostatistics and Epidemiology from the National Institute of Mental Health and Neurosciences (Nimhans) and the department of Speech and Language Studies, Dr S R Chandrasekhar Institute of Speech and Hearing in Bengaluru conducted the study between January and December 2021.

Subsequent findings were published in the peer-reviewed journal Alzheimer’s and  Dementia on February 20 this year.

The study covered 1,234 people aged 60 years and above in south Bengaluru, nearly 54% (665) of whom were women.

The mean age of those studied was 71.18 years. A total of 803 participants – which was 65% of the participants – spoke two or more languages.

The team used a language use questionnaire (LUQ) to test language proficiency, Addenbrooke’s Cognitive Examination (ACE-III) for cognitive function, Clinical Dementia Rating (CDR) scale for the severity of cognitive impairment and Instrumental Activities of Daily Living-Elderly (IADL-E) to understand daily functionality.

All of the tools were standardised and validated for the Indian population.

One of the authors, Aparna L V, PhD scholar, Department of Speech Pathology and Audiology, Nimhans told DH that this study aimed to replicate clinical evidence within a local community in a socio-linguistically diverse context as in Bengaluru.

“We tried to establish previous findings in a community setting. For this, we chose seven wards in Jayanagar to conduct the study. This study revealed that bilinguals were less prone to developing dementia than monolinguals due to the protective effect of using two or more languages,” she said.

The results revealed higher total scores in the cognitive examination, indicating better memory, attention, fluency, language and visuospatial abilities among bilinguals compared to monolingual speakers without cognitive impairment, which indicates that bilingualism also promotes healthy ageing.

Their study concluded that the prevalence of both dementia and MCI was higher in people who spoke only one language compared to those who extensively switched between two or more languages in everyday life.