People who speak more than one language may have a lower prevalence of dementia or mild cognitive impairment compared with those who speak only one language, according to a study published today in Alzheimer’s & Dementia.

“A large body of literature has focused on studying the protective effects of bilingualism against cognitive decline and dementia in clinical settings,” wrote Aparna Venugopal, M.Sc., and Avanthi Paplikar, Ph.D., of the National Institute of Mental Health and Neurosciences in Bengaluru, India, and colleagues. However, the authors noted that only a few community-based studies have investigated the protective role of bilingualism. “India offers a unique opportunity to study bilingualism, cognition, and dementia since the population is non-immigrant and linguistically diverse,” they wrote.

Venugopal, Paplikar, and colleagues conducted a door-to-door community survey in Jayanagar, South Bengaluru, India, from January to December 2021 among individuals aged 60 years or older. Each participant received a clinical examination by a general physician, after which a clinical psychologist and speech-language pathologist administered neuropsychological tests to assess dementia status. Participants completed the language use questionnaire to determine the number of languages in which they were proficient.

A total of 1,234 participants with a mean age of 71 years were included in the study. Among all participants, 1.9% were diagnosed with dementia and 6.5% were diagnosed with mild cognitive impairment. Further, 65% of participants were considered bilingual. Additional findings include the following:

• Dementia prevalence was lower in bilingual participants (0.4%) than in monolingual participants (4.9%).
• The prevalence of mild cognitive impairment was lower in bilingual participants (5.3%) than in monolingual participants (8.5%).
• Bilingual participants had a lower prevalence of dementia compared with monolingual participants regardless of their education levels.
• Bilingual participants both with and without cognitive impairment had higher average scores on Addenbrooke’s Cognitive Examination (ACE-III, a measure of general cognitive function on which higher scores indicate better functioning) compared with their monolingual counterparts. Bilingual participants also scored higher in all five ACE-III subdomains: attention, memory, fluency, language, and visuospatial. These findings were true even after controlling for confounding variables like age, sex, or occupation.
• There was no difference in general cognitive function between participants who spoke two languages compared with those who spoke three or more languages.

“Overall findings indicate that bilingualism promotes healthy aging and protects against cognitive decline and dementia,” the authors wrote. “Our study has implications for public health interventions, highlighting the importance of promoting bilingualism and multilingualism as potential cognitive reserve factors that may delay or slow down cognitive decline.”

For related information, see the Psychiatric News article “COVID-19 Takes Cognitive Toll on Older Patients.”