Many brain functions slow down as we age. New research finds some may actually improve

MARK BRODIE: Lots of our brain functions can slow down as we get older, but new research finds one skill may be exempt from that.

Anne Billot is a postdoctoral researcher at Harvard and Massachusetts General Hospital. Her data suggests that language skills stay about the same as we age, while other skills decline.

When I spoke with Billot, she told me her findings contradict some of the previous literature on brain aging, specifically in the area of language skills and processing.

ANNE BILLOT: So what we investigated was trying to look at two main functions, cognitive functions. So language on one side and what we call executive functions on the other side. So it kind of includes like working memory, attention, cognitive control — all those functions that help us do very complex tasks in our daily life.

And we looked at how these different functions evolve with age, but more particularly, how the brain that supports these functions, how does it change also with age? Because we know that these two different functions change differently, like language is particularly preserved as we get older. Like people typically have very good language even in older age.

But we know that it’s harder to remember things, and it’s harder to do very complex tasks in our daily life as we get older. So we wanted to see what’s going on in the brain related to each of these functions.

MARK BRODIE: So what is going on in the brain? I mean, what is it about the brain that allows us to maybe keep some of those language skills later into life, but not things like memory?

ANNE BILLOT: Yeah, so what what people typically have found in the past about the brain of older adults and what what are the effects of aging on the brain is that people typically found that the brain is getting more kind of mashed together, so different regions more connecting to each other in a way that is less specialized.

So typically in young brains, we would find each function very segregated in the brain. And in older brains, researchers have found that these functions would kind of get synchronized to each other, so less specialization. And we actually use a slightly different approach from what has been used in the past. So instead of looking at the group level, we looked at the individual level. So we try to identify where those regions were related to the language functions or related to these executive functions at the individual level, and then we looked at how these regions behaved in the brain.

And what we found is that the language regions, when we identify them within individuals, they actually show very, very similar patterns as in young adult younger adults. So like the extent of activation, the strength of activation, how well they are synchronized is remarkably preserved in healthy aging. Where on the other side, what we call the executive regions, the ones that are again responsible for like hard cognitive tasks, these ones show a similar decline as what we observe at the behavioral level.

So we found really this contrast between the two different networks that support these two different functions, which hasn’t been really described in in the previous literature, because typically we saw healthy aging in the brain as a general pattern of decline, and not that many studies really looked at each network separately and also at the individual level. That’s kind of the new approach of this study.

MARK BRODIE: Would it stand to reason then that it’s conceivable at least that there are other aspects of our lives that might behave in the way that language does in the brain as we age, and maybe doesn’t deteriorate with age as it seems language does not?

ANNE BILLOT: It’s possible, yes. There are definitely more functions to investigate. Here we really focused on two on these two functions, because what we found in previous studies is that these two functions lie right next to each other in the brain. And so when we average brains across individuals — so when we average multiple brains together — the boundaries between each network kind of gets blurred together, and so in previous studies it was harder to dissociate how these different networks would evolve with age, because we would just blur the their responses together.

But there are other functions like social cognition, for example, that would be very interested interesting to investigate further, because that’s related to what we often call the default network, which is often involved in like Alzheimer’s disease and other neurodegenerative disorders, and so it would be interesting to also investigate how these specific networks for other functions might evolve also with age differently.

MARK BRODIE: We hear so much, especially with newborns and and really young kids, that it’s really important for their language development skills to hear a lot of words and to be exposed to a lot of language. Is there anything to be said about the fact that by the time we’re a little bit older, we’ve been just exposed to that much more language, and maybe that is part of what’s going on in terms of us keeping that function as we get older?

ANNE BILLOT: Definitely. That’s that’s a great interpretation, and that’s actually what what we see like typically when we look at the behavioral level, if we ask people to do different tasks, either language tasks or executive tasks, we definitely see that vocabulary, for example, increases with age.

And so that’s definitely one interpretation of our of our work is what we call the brain maintenance hypothesis. So the functions that are well preserved behaviorally — so what we observe at the behavioral level — are actually supported by networks that are very well preserved in the brain, versus some other functions like memory that is declining more would be supported by networks that are actually also declining in the brain.

MARK BRODIE: Is there anything to be learned from what you have found about the language part of the brain that might be able to help us preserve other parts of the brain that, like memory or executive function as you mentioned, that do kind of deteriorate with age? Like, is there any way to use this to help other parts of the brain that maybe could use it as we get older?

ANNE BILLOT: Yeah, so I think what what is interesting in this work is is to see that these different functions have different patterns, and so I think it will help us develop new studies to to investigate what causes these differences, right? Like we we don’t know yet why this this language network doesn’t decline as fast as this executive network.

But I think overall to really try to preserve our our cognitive functions in general, it’s really important to just keep using our brain, right? It’s a very basic thing to say, but it’s really trying to to use it in in as various contexts as possible. So I think really like trying to to use our brains in all possible ways we can and being active.

And of course language is a big part of that, right? Like talking to people and interacting with people is such a complex task, so it requires just not just our language network, it actually recruits many parts of our brain. As well as young kids have a very plastic brain. As we get older, there’s a thing that if we don’t use a function, we kind of lose it. And so it’s also important to keep doing things that are like recruiting different parts of our brain and asking us sometimes more difficult tasks, because that’s going to preserve our brain and maintain these connections between our different brain regions.

MARK BRODIE: Anne Billot is a postdoctoral researcher at Harvard and Mass General Hospital.