Bilingual brains are more resilient to dementia cause by Alzheimer’s disease

Lifelong bilinguals have increased connectivity in certain areas of the brain that help to protect them from dementia, according to a study published on Monday 30 January.

People who speak more than one language develop dementia symptoms an average of five years later and are able to cope with a greater level of brain dysfunction than monolinguals living in the same geographic area.

Researchers scanned the brains of 85 people in Northern Italy who were all at a similar stage of dementia due to probable Alzheimer’s disease. Forty five of them were German-Italian bilingual speakers and 40 were monolingual German or Italian speakers. Researchers used FDG-PET brain scans that detect glucose uptake to reveal how active different parts of the brain are and how well they are functionally connected to other brain regions.

On average, the bilinguals in the study were five years older than the monolinguals, despite being at the same stage of Alzheimer’s disease. Their brains showed reduced metabolism in key brain areas which implies a greater levels of dysfunction despite all study participants having a similar degree of impairment due to dementia. Compared to monolinguals, bilinguals showed increased functional connections between areas of the brain involved in executive control and the extent to which they use their second language was significantly correlated to activity in key neural networks.

Dr Clare Walton, Research Manager at Alzheimer’s Society, said:

'This elegant study provides new evidence that people who are fluent in more than one language have some protection against dementia. Brain scans showed that lifelong bilinguals have stronger connections between certain brain areas compared to those who only speak one language – this appears to allow their brains to cope better with damage before they start to show outward signs of dementia.

'In terms of lifestyle and risk of dementia, this type of study provides a vital piece of the puzzle – it doesn’t just tell us that bilingualism is linked to reduced risk of dementia, it begins to tell us why. As societies become more multicultural, this study indicates that the benefits of bilingualism could extend to helping future generations reduce their risk of the condition.'