MIT researchers find why these skills can stay strong with age even as memory and attention decline
Ageing is often associated with changes in memory, attention, problem-solving and other cognitive abilities. But one important part of the brain appears to follow a different path: the network responsible for processing language may remain remarkably resilient even as other brain systems change.A new study involving researchers from MIT and Boston University found that activity in the brain’s language network was nearly identical in younger and older adults while they performed language tasks. The findings offer a possible explanation for why many people continue to maintain their language abilities as they grow older — and why vocabulary and reading skills can even improve over time.
What happens to the brain as we age?
The researchers compared two groups of participants: people aged 17 to 39 and adults aged 41 to 80.They focused on two different brain systems. The first was the language network, which is specialised for processing language. The second was the multiple demand network, a more general-purpose system involved in executive functions such as attention, working memory, decision-making and cognitive control.The results showed a striking contrast.During a spatial memory task, older participants showed clear differences in the multiple demand network. Compared with younger adults, their network was smaller, less synchronised and showed weaker overall activation.But when participants performed language tasks, the researchers could not find comparable age-related differences in the language network.“In the language network, we couldn’t find any differences between older and younger groups,” Anne Billot, one of the study’s lead authors, said, according to MIT News.
Older brains responded to difficult language in the same way
To examine the language network, participants listened to stories and read sentences while their brains were scanned.The researchers found that language-related brain activity had similar levels and spatial distribution in both age groups. More interestingly, the two groups also showed similar responses when they encountered an unfamiliar word or an unusual grammatical construction.MIT associate professor Evelina Fedorenko, one of the study’s senior authors, explained to MIT News that younger adults typically show increased activity in language areas when they encounter such linguistic difficulties.The older participants showed the same sensitivity.“This suggests that there’s nothing fundamentally different about how they process language,” Fedorenko said.The researchers also found no evidence that the language network became less synchronised with age. Nor did they find signs that the language network was becoming blurred with the multiple demand network, another possibility scientists had previously considered.
Why can language remain strong while other abilities decline?
The researchers believe the difference may come down partly to how these brain systems work.The multiple demand network acts as a flexible resource. It helps people adapt, solve unfamiliar problems and perform tasks that require cognitive control. Unlike language knowledge, however, it does not continually accumulate information throughout life.The language system, by contrast, works with knowledge that can keep expanding.Vocabulary is one example. People continue encountering words throughout their lives, through conversations, reading, education and other forms of exposure.“Vocabulary keeps increasing as long as people have been measuring,” Fedorenko told MIT News. She compared the process to a large language model being trained on increasingly more data.That accumulated knowledge could help explain why some aspects of language actually improve with age.
What this means for ageing and education
The study does not directly measure whether individual participants became better or worse at language. Instead, it examines the brain activity associated with language processing.Still, the findings point towards an important distinction in healthy ageing. Brain systems dedicated to specialised functions may be more resistant to age-related changes than systems responsible for flexible, general-purpose thinking.“The multiple demand network is a different system in the sense that it’s not accumulating knowledge over time,” Fedorenko said. “It’s more like a flexible resource that you can deploy in all sorts of ways. And somehow that’s the thing that is more vulnerable to aging.”The researchers say the reason for this difference remains an open question. Their findings, published in Nature Communications, nevertheless provide another clue about how the ageing brain changes — and why getting older does not necessarily mean losing every cognitive ability.For students and lifelong learners, the research also highlights an encouraging idea: while some mental abilities may become more vulnerable with age, the brain’s capacity to work with accumulated language knowledge can remain remarkably stable.Disclaimer: This article is based on research reported by MIT News and published in Nature Communications. The findings have not been independently verified by TOI Education.
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