ParentsBrought to you by

‘Future criminals revealed at age three’? Not so fast, says Dunedin Study head

For good or ill, the first three years of a child’s existence have an outsized impact on the rest of their life, according to findings taken from the world renowned Dunedin Study. The study’s director talks to Toby Manhire about what it all means.

Give me a child at seven, and I will show you the man, said ancient thinkfluencer Aristotle back in the day. New findings that emerge from the Dunedin longitudinal study published this week suggest that they can go a fair bit younger still: give me a child at three, and I will assess their brain health before telling you whether they’re likely to be an economic burden as an adult.

The report, published in the journal Nature Human Behaviour, drew on the Dunedin Study, which has followed the progress of just over a thousand children born in the city in 1972 and 1973, measured alongside, with the anonymous participants’ approval, personal government and medical data.

Their core finding: “A small segment of the population accounts for a disproportionate share of costly service use across a society’s health care, criminal justice, and social welfare systems – and paediatric tests of brain health can identify these adults as young as age three … The team … found that nearly 80 per cent of adult economic burden can be attributed to just 20 per cent of the Study members. The researchers determined that this ‘high cost’ group accounted for 81 per cent of criminal convictions, 66 per cent of welfare benefits, 78 per cent of prescription fills and 40 per cent of excess obese kilograms.”

The Spinoff spoke to Dunedin Study Director Professor Richie Poulton, to ask about the findings, how it fits into Bill English’s “social investment” approach, and the risk of stigmatising children.

Photo: Santiago Urquiljo / Getty Images

Photo: Santiago Urquiljo / Getty Images

The Spinoff: One of the major news headlines reporting on the findings read, “Future criminals revealed at age three”, which has a bit of a Minority Report edge to it. Is that headline true?

Richie Poulton: No. It’s a headline that doesn’t reflect what’s in the paper accurately. There were unfortunate headlines.

What then are the major findings of this study?

The idea, which is intuitively appealing, is that there is a small group that account for a lot of service use. It’s been described in New Zealand as “seven Datsuns in the driveway” – every service turning up to the same family. We thought it would be a good idea to test this empirically, and use the Pareto principle, which is the 80-20 rule, as a guide. So we looked at the relationship between a number of childhood risk factors and the likelihood of ending up using multiple services: the Ministry of Social Development, benefits, getting a criminal conviction of relevance to Justice, health service usage and pharmaceutical use relevant to health, and so forth. And we found support for the idea that about about 20%, just over 22% in our case, were users of multiple services.

We did that because we’re able to link the administrative databases that have national coverage, from each of those ministries, with our in-depth data on development from the Dunedin Study. So you’ve got not too much depth in terms of the national administrative databases, coupled with the small scale but great depth of the Dunedin Study.

So once we’ve identified our group, and it does look like an 80-20 rule, the question becomes how do you predict those people? How do you determine who they are? The theory being if you could identify them you might be able to do something about it.

So we went back into the database, and the thing I think that has caught most people’s attention –you will have seen this in the various coverage of the paper – is that we could go back as early as age three and get a very strong prediction of who ended up in that group that used 80% of the services. That’s unusual for this sort of research, because most of the findings linking childhood attributes or risk factors to adult outcomes report statistically significant, but rather small effect sizes or strength of association. We found quite strong prediction – the take-home point of that being that if you segment the population into those most at risk of using services, the risk factors end up being very strong predictors.

What are those risk factors?

The risk factors in our case were three or four different ways of measuring brain function and brain health. We were able to show that from as early as age three, and the strength of prediction in real terms was that, if there were two people, you and I, and someone was trying to pick which one would end up being in the “bad group” so to speak, versus being in the “better group”, you get that right 80% of the time. So that addresses the false positive concern, and also the false negative concern, in trying to predict.

How did you measure brain health?

We didn’t rely on any particular measure. We used a combination at age three. It only took 45 minutes to obtain the information. And that immediately becomes of interest to a government. You don’t have to do in-depth studies over long periods of time to figure out that at age three, who is in this high-risk group that will then predict huge amounts of cost.

By the way, I’m just talking about economic cost, because that’s what we looked at. Behind each of the economic indicators sits a whole lot of personal and family suffering. That’s probably what I’m more concerned about, given my background in mental health.

But that’s the value – you can do something in 45 minutes. The things we measured included the ability to express language, to understand language, fine motor ability, some neurological signs – just basic reflexes – and also an important trait or ability called self-control, which is about emotion regulation. So that combination, by age three, told us a lot about who would be in the group and who would therefore have those high costs across the first half of their life course, at least – this is to age 38.

If you’re trying to understand how to get the best return on investment as a government bureaucrat or as a politician, this should be of enormous interest. It says when to intervene – it’s before age three, you don’t wait till three, because neuro-development starts with conception – you want to make sure that all your services are aligned in such a way that they’re optimising neuro-development from the very get-go, because it seems to matter tremendously. It’s very much the empirical test of the social investment paradigm that Bill English has been pushing for a number of years.

It’s like a welcome present to Bill English PM, these results, in a way.

I presume he would be happy about data that kind of aligned with where he is going rather than the reverse. He’s had a few non-welcome presents in the first few days, so maybe this one will be on the other side of the ledger.

You mention in the paper the risks of “stigmatising”. Partly given the headlines, and partly given the language that one inevitably slips into – you’ve just used the term “bad group” as a shorthand – those are real dangers, aren’t they, that we start sticking labels on three-year-olds?

Indeed. We were at pains in the paper to point out that this is not part of something which justifies stigmatising or using pejoratives like I did as shorthand. Language does matter a great deal. I would talk about these people as vulnerable. It’s about identifying vulnerability early and providing extra support so they can acquire the skills to make a success of their lives.

This is not something that will return only to that group. If these people are given that support and do well and don’t use all those services, everyone in society, all taxpayers benefit. So that’s the way we’ve framed it, it’s what we believe is the most rational way of understanding this information and using that to good effect. Of course you will have people, for whatever reason – personal, self-interest, ideology, politics, whatever – interpreting it in different ways. But we, as the people who generated this knowledge or information, are very clear about what it means. To do otherwise would be almost unethical. You need to identify vulnerability to actually help address it. You can’t put your head in the sand and pretend it doesn’t happen.

What about the generational issues – given the data from the Dunedin study looks at people who were age three many decades ago. Are there dangers there?

There are certain types of exposures or experiences that people have that are particular to certain times. But we’re talking here about abilities that are vested within the individual that are pretty universal through time. So we’re talking about, essentially, neuro-development, or brain health.

You could probably expect that what we’ve found today on our cohort would apply to people that were studied in the future, or had been studied before us. Neuro-development, or brain health, or brain integrity, is just so important to how people’s lives turn out, and I don’t think that will surprise, or shouldn’t at least.

What’s next up for the Dunedin Study?

Right now, we’re in the throes of gearing up for our next big assessment. So, come April, we’ll be starting again, to bring everyone back, from wherever they are in the world. And we’ll run that assessment for about 20, 22 months.

Before beginning that – and this is a huge exercise to launch and run – we’ve begun something for the first time: a study of neuro-imaging. So we’re taking pictures of people’s brains, both the structure, what it all looks like in an aesthetic sense, but also function. So we have a number of tests that people in the MRI machine have to do. That lights up certain parts of the brain circuitry, depending on the nature of the task. And we’ll get to understand how people’s brains are working, as well as whether different areas and the level of function across those areas, is related to real world outcomes which we’ve measured on our cohort since they were born.

So that’s all very exciting and new stuff, and we’re getting the large share of the funding for that study from America. The National Institute on Aging in America want to get a normative sample that’s been really well characterised in their suite of investments across the globe to better understand what normative development looks like in the brain. Mainly what they’ve invested in is either very small samples of children or older people. So that’s something that’s new and novel and exciting.

Follow the Spinoff Parents on Facebook and Twitter.


This content is entirely funded by Flick, New Zealand’s fairest power deal. In the past year, their customers saved $417 on average, which would buy enough nappies for months… and months. Please support us by switching to them right now.

The Spinoff Longform Fund is dedicated to facilitating investigative journalism. Our focus is on supporting in-depth reporting on important New Zealand stories. Your donation will help us sustain this most resource-intensive form of journalism, ensuring that the most complex and important stories still get told.