Does an extra year in school change your brain?

In 1972 a pint of milk cost 6p, and a litre of petrol - leaded of course - was only 8p. Weren’t those the days! But in that same year, when Alice Cooper released the hit song Schools Out an important change occurred in the UK education system: the school leaving age was upped by a year, from 15 to 16. And this presents scientists with an opportunity: if education boosts brain power - which it arguably must - then what would we see if we compared the brains of broadly similar people who either did, or didn’t benefit from that extra year in school? That was what Nick Judd and Rogier Kievit, at Radboud University, wanted to know. Nick first…

Nick - We know that education is one of the largest positive impacts out there. It's a major contributor to socioeconomic disparity and it's correlated to almost every positive life outcome. So we were really interested in if it had effects on long -term structural changes in the brain. So we looked at around six different structural brain metrics, so how big your brain is, how thick your cortex is, the surface area of your cortex, also the volume, fractional isotropy, which is pretty much just how white matter diffuses in the brain. We pretty much took an approach to try to look at almost every structural property.

Chris - And Roger, what was your approach here? Where did you get the data from?

Roger - Yes, so we used a very large project from the UK called Biobank, which has hundreds of thousands of people in it. And we use the fact that in the UK there was a law change in the 70s where people were forced to go to school for an additional year. So before every child had to go to school for at least 15 years and after that for 16 years. So we could use that change in the law to compare children who were born just to one side of that cutoff. So we could use that data to look at their brains years later and compare the people who only differed in how long they had to go to school.

Chris - That's quite a considerable intervention, isn't it? An extra year of education. So if something, I suppose your rationale is if something's going to make a difference, this will be it?

Roger - Yes. So for years, people have used brain training games for sometimes minutes or hours in the hope that that would yield long lasting consequences. So we thought if you go to school for a whole additional year, we might stand a chance of seeing something in the brain even a few decades later.

Chris - And what do you find, Nick? Is there an impact of doing an extra year of school?

Nick - Yeah. So we didn't find an effect on any of our measures. So we also looked at different regions of the brain and we didn't find any effect on any structural brain measures. A key distinguishing part of our approach to prior research is this natural experimental approach, which allowed us to really isolate and tease apart education in itself from all the societal factors that might lead some people to receive more education than others.

Chris - You must have been a bit disappointed, Roger, when you got that result. You must think, well, actually, we were hoping we were going to show this dramatic difference. You saw nothing.

Roger - Well, we tried to be dispassionate and not be too disappointed. But we also thought it's interesting precisely because we do know that education does have long term benefits on your cognitive ability. So how well you can remember things or think about problems and on health. So we know that this educational intervention did have an impact in the same people we looked at, but we just weren't sure whether the impact would be in the brain in the long run. And the way we thought of it is maybe it might be like going to the gym that might bulk up your muscles for a few weeks or days or months. But maybe if you don't use the same muscles for a long time, then maybe 20, 30 years later, you don't see the same impact.

Chris - We've just seen a paper in Science Advances where a German study has looked longitudinally at a relatively small group of people, but they find people doing cognitively demanding jobs, which appear to stretch the participant, do appear to maintain their cognition for longer than people doing less demanding jobs. So do you think that the education just gives you access to the lifestyle that gives you the sorts of benefits, Nick, that you're saying accrues through education? Or is it something else that's going on here?

Nick - Just to clarify, the effect of education on IQ and other cognitive abilities is pretty well established with natural experimental designs. So it's really, we don't pick it up in the brain. But the beneficial effect of education on cognition is there.

Chris - Do you have a reason for why that might be, Roger? Can you speculate as to why it can have these profound effects, but it's not reflected in the brain? Are we just not looking hard enough? Or is the resolution of our imaging not good enough to pick up something that's probably a bit too subtle?

Roger - Yeah, so those are a few of the things we've been discussing. One thing we would have liked to go back in time and study people's brains right after they had the additional year of education, because that would be the best comparison to see right when the children spent an additional year in the schools, do we see effects on their brains at that moment? Because maybe there was an effect initially, and then it essentially faded out. And there's some ideas that your brain might have this short -term reorganization that is visible. And the way we think of it is like roadworks. There's a lot of noise and mess, but after a while it reconsolidates. We call that renormalization. Your brain goes back to normal and it's almost as if nothing ever happened. But those benefits for your brain are still there. They're just not there at the level we can pick up with an MRI. So the other possibility is that using a different scan or looking at functional activation that we might find these traces of the effect there. But given how much people use this exact MRI technique, we thought it was valuable to see, can we find these effects using this type of scanner?

Chris - The take home messages, what do you think is really the bottom line here then?

Roger - Well, the bottom line I think is that to understand how the brain develops, we have to study it developing. And that sounds a bit obvious, but for a long time we only had the techniques and the money and the resources to study one brain once. So you come in, you get scanned, but increasingly we're realizing to really tease apart this puzzle of how our brains develop and how they allow us to do all these wonderful things. We need to see how your brain changes over time. So more and more neuroscientists are scanning people, say, every year while their life unfolds. I think that's going to give us a lot more new insights over the next years and decades.