In this podcast, we talk to Professor Mark Tomlinson of the Department of Global Health Institute for Life Course Health Research, Stellenbosch University in Stellenbosch, South Africa.
The focus of this podcast is on the JCPP paper, ‘First 1,000 days: enough for mothers but not for children? Long-term outcomes of an early intervention on maternal depressed mood and child cognitive development: follow-up of a randomised controlled trial’ (doi.org/10.1111/jcpp.13482).
Mark is the lead author of this paper and sets the scene by providing insight into what prompted his interest in both young people’s mental health and, in particular, the impact of maternal depression on infant and child development.
Mark talks us through what his paper looks at, why he decided to research this area, highlights the methodology used in the paper, and shares his findings.
Mark then provides further insight into the finding that, although the paper describes how caregivers who received a home visiting intervention during their pregnancies and postpartum did show lasting improvements in depressed mood, and that the intervention was also associated with mothers being more sensitive and less intrusive in their interactions with their infants and to a higher rate of secure infant attachment at 18 months, there was a lack of long-term developmental benefit for the children.
Furthermore, Mark also discusses what message professionals, researchers, and policymakers should take from his findings, and provides additional information with regard to follow up research.
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Professor Mark Tomlinson is the Co-Director of the Institute for Life Course Health Research in the Department of Global Health at Stellenbosch University. His scholarly work has involved a diverse range of topics that have in common an interest in factors that contribute to compromised maternal health, to understanding infant and child development in contexts of high adversity, to understand the impact of maternal depression on infant and child health and development, and how to develop community based interventions to improve health and development across the life course. He has been a consultant for the World Health Organization, USAID, and Conrad N Hilton Foundation. He was one of the co-ordinating writers of the World Health Organization document – ‘Nurturing Care for Early Childhood Development: A Framework for Helping Children Survive and Thrive to Transform Health and Human Potential. He is on the Editorial Board of PLoS Medicine; is an Associate Editor of Infant Mental Health Journal, and is also on the Editorial Board of Psychology, Health and Medicine. (Bio. from Queen’s University Belfast, pic. from ILCHR)
[00:00:00.370] – Jo Carlowe: Welcome to a different type of In-conversation podcast from the Association for Child and Adolescent Mental Health, ACAMH where we will look at the paper, ‘First 1,000 days: enough for mothers but not for children? Long-term outcomes of an early intervention on maternal depressed mood and child cognitive development: follow-up of a randomised controlled trial’ published in the Journal of Child Psychology and Psychiatry, the JCPP. I’m Jo Carlowe, a freelance journalist with a specialism in psychology, and I have with me Professor Mark Tomlinson of the Department of Global Health, Institute for Life Course Health Research, Stellenbosch University in Stellenbosch, South Africa.
[00:00:40.510] Mark is the lead author of the paper we’ll be discussing today. If you’re a fan of our In-conversation Series, please subscribe on your preferred streaming platform. Let us know how we did with a rating or review and do share with friends and colleagues. Hi, Mark, thank you so much for joining me. Can you start with a brief introduction about yourself?
[00:00:58.500] – Professor Mark Tomlinson: Thank you, Jo. Great to be here. I am the Co-director of the Institute for Life Course Health Research, which is based in the Department of Global Health at Stellenbosch University in Cape Town, and my research basically has over the years mostly been around child and adolescent mental health, tracking cohorts of children across time to track development, understand mechanisms, pathways of development. I always had a particular interest in maternal mental health as well as early child development.
[00:01:28.950] – Jo Carlowe: Can you say what prompted your interest in both young people’s mental health, but in particular, the impact of maternal depression on infant and child development?
[00:01:38.150] – Professor Mark Tomlinson: Actually, I had no intention of ever being a researcher when I was at University. Initially my intention was to become a clinical psychologist, which I eventually did become after a long and winding road, but initially after my first four years of University I went and I worked in a child and youth care agency. A residential child care setting where children had been removed from their caregivers, parents for one reason or another, and that’s really what sparked the interest in young children’s development. How in some cases it goes off track and what can be done to bring the development back on track?
[00:02:16.790] – Jo Carlowe: Mark, let’s turn to the paper. Can you set the scene for us? What did you look at and why?
[00:02:21.980] – Professor Mark Tomlinson: This was a very interesting study in that we had completed an early intervention, a randomised control trial some decade and a half prior to the study, and that study initially was funded by the Wellcome Trust and then Grand Challenges Canada put out a call for very interesting, sort of, set of studies of follow up, and intervention in the first 1000 days, and they were now interested in tracking what happened to those children in terms of their cognitive development. There were lots of other things they were interested in, but cognitive development was their primary focus and this was quite unique.
[00:02:58.030] People, you tend to do a randomised control trial, you follow up a year later, and in most cases that’s where the study ends and where there’s some, but there’s not enough these long-term follow up to understand whether early effects maintain, whether we can still see them down the line. So we were successful and with this funding we were now able to follow them up in their early adolescence.
[00:03:21.080] – Jo Carlowe: Can you say something about the methodology you used?
[00:03:24.550] – Professor Mark Tomlinson: As I mentioned, the original study was an individual randomised control trial, fairly small. There was a total of 450 pregnant women, initially half in the intervention group, half in control, and then in this early adolescence, when we followed these children up it was just trying to find as many of these caregivers and their children as we could, and where the original study had taken place there’s quite a high level of migration of people moving in and out, back to the Eastern Cape, rural Eastern Cape, where many families come from or to other parts of South Africa.
[00:03:58.730] And in fact we hired a full-time recruiter who all they did basically for 18 months was tracked down participants because we’d had no contact with them for close to a decade, and we found them in over 30-35 towns around South Africa. We basically, either if they’ve in Cape Town we picked them up or if they were elsewhere we paid for the caregiver and a child to travel down to our research site in Khayelitsha, which is just outside of Cape Town.
[00:04:21.900] – Jo Carlowe: And how successful were you in terms of recruiting?
[00:04:24.920] – Professor Mark Tomlinson: Well, I think we were hugely successful. We managed to find just under 80% of the participants, which is quite remarkable given that when we started the study there weren’t even mobile phones. The contact details that we had for people in their ten-year time were often landlines. So before mobile phones were available. So people had landlines, and even when they migrated to a mobile phone because people in the sample, the caregivers were very poor. They often shared phones with other relatives who then kept that phone and they were without a phone.
[00:05:02.550] So it involved many, many reference points and phoning the neighbour, the neighbour knowing a friend, the friend knowing someone in Johannesburg. It was quite a lot of detective work, but we managed to get close to 80% which we were very happy about.
[00:05:16.480] – Jo Carlowe: Mark, what can you share of the findings?
[00:05:19.100] – Professor Mark Tomlinson: We were very interested from the point of view of the funder that funded us in cognitive development. So that was the primary outcome that we were interested in from the point of view of the funders, but given that our early intervention had really been about focusing on the infant relationship, on mother-infant attachment, for example. We were quite interested in also looking at a whole range of emotional measures in terms of child development, and in the early trial that we’d done we weren’t focusing on maternal mental health or maternal depression at all.
[00:05:52.740] But at six months and again at 18 months there was the signal that something was happening in that regard. Even though we didn’t focus on it, there appeared to be a little bit less depression in the one group it wasn’t significant. So we made very little of it at the time, but we were also interested in following that up. So when we followed these children, their caregivers, up at 13 years, we found that there were no differences in child cognitive development. So that early intervention didn’t impact on cognitive development which was, of course, disappointing.
[00:06:24.230] But having said that, it wasn’t an intervention focusing specifically on the technical aspects as it were in terms of stimulation, for example. In terms of particular executive function tasks that you might include in an intervention if you were focusing on cognitive development. So it was disappointing, but it wasn’t too much of a surprise. Where we were surprised was that in fact there was an effect, a very small one, which is important to say, on maternal mental health. So at age 13, which we found quite remarkable, that sort of 13 years after having received an intervention, that those caregivers who had received this intervention, focusing on them, of course, but them and their relationship with their infant had an impact on their mood that long after.
[00:07:06.140] Now, it is also important to say we didn’t diagnose maternal depression, for example. It wasn’t a diagnosis. It was a screening tool. So it really was women at risk of depression but we were quite heartened by that, because we know from a wealth of research, both that we’ve done in South Africa, but in many other parts of the world that maternal mental health is implicated in a number of difficulties in child and adolescent development. Whether it’s behaviour, in some cases, cognitive development. So it was heartening that this early intervention had had some effect over a decade later.
[00:07:40.450] – Jo Carlowe: I just want to go into that in a bit more detail. So the study finds no overall intervention effect on child cognitive development at follow up when the children were 13. Although in the paper it describes how caregivers who received a home visiting intervention during their pregnancies and postpartum did show lasting improvements in depressed mood. The intervention was also associated with mothers being more sensitive and less intrusive in their interactions with their infants and to a higher rate of secure infant attachment at 18 months. So given this, how do you account for the lack of long-term developmental benefit for the children?
[00:08:23.150] – Professor Mark Tomlinson: I think one of the reasons we called the paper, around ‘the first thousand days’ is because there’s been a very important focus in the last, probably, I suppose ten years on this period of the first 1000 days, and it emerged because of very substantial research into how the brains of infants are just markedly growing. It’s quite remarkable the rate of growth, the size of the growth of the brain, and everything in those early years and the importance then of this foundational period, these first thousand days, and with that has come a lot of absolutely fantastic things.
[00:09:03.390] There’s much more of a focus on how early development is so important. Then if you intervene early you’re setting up the foundations for later development, and it’s absolutely foundational, and it’s absolutely vital, but one of the consequences of that focus has also been this idea that if you get it right early, that if you put all the right things in place, that then this has this amazing impact all the way through life, and this has been supported by a very well-known study in Jamaica, where they did a very early intervention, and they’ve been showing impacts of that intervention up to now.
[00:09:40.800] I think the latest study is looking at those children who received that early intervention in their 30s. So a real long-term follow up, and there have been a couple of two or three studies in the United States which have done very early intervention does maintains this long-term benefit, but in my mind, in many of the studies we’ve done and a lot of other studies is that it hasn’t always proved to be the case. That you can have these very strong early effects, but that at some point they appear across the life of the child, the family, to disappear.
[00:10:13.070] And some people call this fade out. That the results fade out, and there are many studies, in fact, even in the United States and Europe where this fade out has also happened. So trying to understand why is it that in some of these studies the children seem to be doing markedly better, they have higher wages, less divorce or 20 years down the line, and in other studies by two years later or five years later it appears as if all the benefits have now washed out and disappeared.
[00:10:43.220] One of the reasons why I think Grand Challenges were so visionary in fact, in putting this funding together was I think they eventually funded 12 or 13 studies, and if you look at those studies you’ll see exactly what I’m saying. You’ll find one study, for example, the very original Kangaroo Mother Care study that was done in Colombia. They followed those original Kangaroo mother babies up to when they were in their 20s, and they found some really important impact still in 20 years’ time and then other studies that showed no effects.
[00:11:14.940] So trying to now tease this apart, work out what it is. There are obviously many reasons for it, but one of the conversations I had with someone called Natalie Charpak, she in fact was the one who led the Kangaroo Mother Care Study. She said that she thinks the reason for the long term effects were less about the actual kangaroo mother care, although she said, we obviously know that that was really important for survival and infant growth, but she said that what it did at the time was brought the family together, brought support systems together around the baby that was premature and extremely low birth weight and that that connections and bringing them together that she said they could track over time and that maintained.
[00:11:59.050] And she said at the time, I remember when she was presenting her results, she felt that was the reason for the long term growth, not necessarily the actual mechanics of the early intervention. Now, I don’t think we have data for that, but I think her input thoughts on that are quite important. That’s where we came in and trying to understand some of the mechanisms of this, and again remember that in any original randomised control trial or any follow up, to some extent, all you’re doing is you’re analysing the difference in the mean.
[00:12:30.540] You’re always going to have even an intervention group where it’s benefiting. There’s some families and children there who aren’t benefiting at all, and some that are in fact benefiting much more. So again, we also in the study looked at some genetic factors that may play a part in what’s known as differential susceptibility. We also looked at, for example, cortisol in this very same, in the Tulasana follow up study. So, for example, we found that even though there were no group differences in cortisol at the follow up based on intervention or not, we found that you could quite reliably predict cortisol in these children at age 13, when they were put in a stressful situation, like a laboratory task where they had to give an unexpected presentation to a whole lot of rather glum looking people in a doctor’s coat.
[00:13:20.180] And we measured their cortisol and we found that we could predict the levels of children whose cortisol levels didn’t return to baseline as quickly as others by how sensitive their mothers had been in interaction with them ten years before. The picture is a very complicated one. We definitely don’t have anything close to all the answers, but there’s something about certain groups of children which seem to really benefit from an intervention, others that seem not to. That some the benefits disappear very quickly and others not. So that really is sort of the real thinking behind the study.
[00:13:57.950] – Jo Carlowe: The mothers appear to benefit though, because in the paper you state that the improvements in maternal mood are important. Can you say something about that? Why is that important?
[00:14:11.670] – Professor Mark Tomlinson: Maternal depression had never been the specific focus. We’ve done epidemiological work in the same community, and we’ve shown that the rates of depression and at that time it was, in fact, a diagnosis of depression were very high, and it’s a context of very high levels of poverty, of violence, of adversity. Many of the women are single. The father isn’t around in many, many cases. We know the role that paternal care in those context plays initially even to the point of obviously infant survival, but after that in terms of child development and a caregiver that is struggling with mental health difficulties tends to, and again this is a gross simplification, but there are sort of two ways.
[00:14:55.010] There’s a kind of a bit of withdrawal, a remoteness that can happen, which is what one would sort of, in a common sense way imagine happens in depression. That they become remote from the child, but another way is that they become overly intrusive. Don’t allow the child its own space and we know that that can have, if it’s again one episode that’s dealt with well where the caregiver gets support and treatment, if necessary, the impact on the child can be minimal.
[00:15:22.960] But if it’s chronic, if there are many episodes that does have important implications for child development. So we know again, from studies throughout the world that children of depressed caregivers are, and just to say, I should have perhaps said this at the beginning, all the participants in this study were the mothers, but the same is true for fathers. So that’s why sometimes slip into a caregiver. You know, you could be cared for by your grandmother. It’s not your biological mother, but if she’s depressed it’s equally not optimal for the infant.
[00:15:53.180] So trying to understand impacts of maternal mental health difficulties across time has been a particularly interest of mine, and in fact we have another cohort of children we’ve been following for about eight to ten years now, and we’ve also shown there that basically one episode say, for example, of maternal mental health struggles when the child’s age two, for example, can have an impact, but it’s much worse if it is more episodes, chronic episodes, and that can have implications from child growth to, as I said, cognitive development.
[00:16:26.050] And then as you move into adolescence, and that’s why we are also quite interested with this particular group of children, because they were in the early adolescence, is that if there’s maternal mental health difficulties then that can have implications for children then obviously as they move into high school, but equally in terms of peer relationships, of getting involved with substances, potentially getting involved with gangs. I’m not saying that a caregiver with a mental health difficulty is causing a child to end up in a gang. It’s much more complicated than that.
[00:16:56.880] But in context of adversity, when there’s lots of adversities, what we try and do obviously is to what extent can we reduce the number of adversities because that we know can then also assist a child as it goes through its life.
[00:17:09.700] – Jo Carlowe: And this impact later in adolescence is this related to fade out of early intervention, because if I’ve understood it correctly, early intervention does benefit the mother, her maternal mood changes. She might become less intrusive. She might become more attuned to her child in that early period and yet the long term developmental benefits for the child that might not translate into that. So do you mind returning to the concept of fade out? Why does it happen and more to the point what could be done about it?
[00:17:42.150] – Professor Mark Tomlinson: Right. That’s like a spot on question. I think the most important point for me almost of the paper is to say is that in conditions of high adversity you must intervene as early as possible. That’s a given. We know that there are lots of impacts of those early interventions. If they are a sufficient length, are of sufficient quality, we know they can have massive benefits for both the caregiver and for the child, but the mistake that often is made is that then, in a way now, because you’ve got the foundations right.
[00:18:16.030] Somehow the rest of the house to use a rather overused metaphor is now going to build itself. It’s not, although in some context it might be. There might be a family that is struggling at a point early on. They get the support from a community health worker who goes in. It’s a revelation for them at the time. They connect with other support mechanisms and actually their child now and themselves in their relationships with the child and with others it’s now sort of in a way, just put it back on the right track and we can leave them to thrive as it were.
[00:18:49.790] But in context of adversity for many children early is not enough, and that’s my most important point is if you imagine that you can just do that and now you’ve done your job and that a lot of families aren’t going to need more intervention across the life course, then you’re making a big mistake because then in a sense you’re having the short term benefits, but if there’s no long term benefits, is that really worth it? I don’t know. I don’t have an answer for that. It might be, but in fact, what we need to do is we need to work out in a better way which families, in fact, need to be targeted. There’s a sort of a famous, a well-known public health triangle of what we would call universal approaches, targeted approaches and indicated approaches.
[00:19:31.320] The idea of universal is that everybody needs it. It doesn’t matter who you are. If you’re in London right now and you’re pregnant, you go to antenatal care. Every pregnant woman goes to antenatal care. That is a universal service. We know it’s a universal good, and everyone gets it. In context where they’re low resources such as ours or many, many even poorer countries in Africa and elsewhere there may be universal services such as antenatal care, but then the few resources are in a way we often try to give them to as many people as possible obviously, because the need is so high and a slightly different take.
[00:20:07.790] And again, this doesn’t mean I’m saying deprive some people from that, but let’s determine what’s universal. So in our case this early intervention of community health workers visiting women at home for the first visiting pregnancy in the first six months of life is a good thing, and everyone should get that. The question now is can we then work out in the course of that which families now are going to need something in a year’s time, which ones will need because of availability of caregiver things will they need a very particular kind of preschool to go to. The kinds of things that would probably happen routinely in many high income countries where children are assessed continually in an ongoing way. They work out what they need, they get a sense of remediation.
[00:20:51.570] So we need better to work out which families need a little bit more and then which families, in fact, need a whole lot more? That for me, is my main conclusion from that paper is that if we just stop at 18 months or stop intervening at six months you may have a very small effect on maternal mental health down the line, but you’re not substantively impacting child development. Whereas I would propose that had we then had the resources to then deliver, for example, when those children, because we did stop when they were six months, so they were still babies.
[00:21:25.650] But when they were, say, 16 months or so, we’ve done a lot of very successful work on shared reading also in a group context, using shared reading with caregivers and their 16 months old. So if you have this early intervention and then you build on that at preschool and you make sure when they go to grade R, the reception year in South Africa that they’re getting stimulation. If you build those on top of that early foundation then you’re likely to be able to avoid that fade out and that wash out of impact.
[00:21:58.620] – Jo Carlowe: So it’s something about continuous intervention and how it’s targeted, because it strikes me that one could look at the outcomes highlighted in your study and conclude that there is little benefit to funding early intervention programmes of the sort described, and I would imagine that that is not the conclusion that you want people to draw. So, Mark, what message should professionals, researchers, and policymakers take from your findings?
[00:22:27.120] – Professor Mark Tomlinson: Firstly, and thank you for putting it like that, because that’s absolutely not the conclusion that somehow now we must stop investing in early intervention, because that’s absolutely what we were able to show is that even in a context of such adversity we were able to really change some really important factors, such as attachment, which we know has implications down the line. Mother and infant response of care giving. So we did have impact. So the early intervention is important. What we’re always trying to do, I suppose in any interventions, we’re trying to create an enabling environment that allows children and caregivers and families to meet their potential.
[00:23:04.590] And no one thing I would contend makes children meet their potential, and anyone whose, even if you live in a high income country, knows that it’s not one thing that’s successful because there’s lots of bumps and traumas along the way, and it’s a whole series of things, stability, good schools across a life course that really contribute to optimal development. For example, if I go back and I think of that Jamaica study that had such good impacts in a similar context to South Africa, but one of the things, for example, in Jamaica at the time, and I don’t know the exact figure, but they have near universal preschool education.
[00:23:45.260] So children received that early invention. Most of them would have ended up going through preschool. In our context, sometimes less than 50% of children will go to preschool. So again, one could argue, it doesn’t necessarily have to be a separate intervention, like somehow us going to community health workers and delivering another intervention. It’s just making sure that the institutions, the services that come later in the child’s life are optimal, are of good quality and that they can then build on that early benefit from early intervention.
[00:24:20.930] So that would be my main conclusion. The other one that we need much more research on and every researcher says that at the end of every paper, you know, more research is needed. I know, but we don’t know enough about the mechanisms of this across time. About why is it that some families and some caregivers seem to benefit so much from interventions and others seem to benefit perhaps a little, but not really very much, and others not at all. What are the factors, and to try and understand those cross time, because one of the problems we have is that so many of the studies that we do, the early intervention studies, if you’re lucky you get funded to twelve months to follow up twelve months post the intervention.
[00:25:02.760] Tracking across time is incredibly expensive and time consuming and funders on the whole aren’t interested in that kind of investment across that period of time when they’re not quite sure even what the result is going to be. So we need more funding of what’s called longitudinal intervention cohorts, because the UK, I mean, you’re the leader in the world on cohort studies, birth cohort studies. You’ve got more than anybody and well-funded and the government has funded those since post-World War II. Massive knowledge about child development has come from those cohorts.
[00:25:38.610] But one of the limitations of those is that there wasn’t intervention. It’s just tracking development, and that is important. We need some of those where you have a very big intervention, big numbers of an intervention and then perhaps re-randomise along the way and target families and give them a different kind of intervention later and see what happens across time.
[00:26:01.070] – Jo Carlowe: Well talking about the need for more research, are you planning some follow up research that you can reveal to us?
[00:26:07.540] – Professor Mark Tomlinson: Yes. Well, actually this study we were also then with the same cohort lucky enough a couple of years ago to get some funding to follow up the cohort again at age 17 years old. So at the moment we’re in the process of, I don’t have any results as yet, but we managed to then be funded for another follow up. So watch the space and we’ll be able to hopefully give more data around, for example, does the impact of maternal mental health maintain, for example, or there is another interesting aspect to some of these longitudinal intervention studies.
[00:26:41.590] And there was quite a well-known study many, many years ago. Early nutrition study. I think it was in Guatemala where they found very strong early impacts because of their nutritional intervention. When they followed those children and caregivers up at age 15, I think, all the benefits had disappeared. Then they managed to get funding at age 25. And what had happened and this is another term that gets used is called like there’s fade out and there’s something called resurrection, where all of a sudden the early benefits seem to re-emerge much later.
[00:27:12.500] Maybe that’ll happen, and that would be lovely, but again just trying to understand the complexities of these pathways and whether it’s fade out, it’s resurrection or findings all the way along the line. It does feel like it’s an important agenda to further.
[00:27:29.130] – Jo Carlowe: It would be great to see how it pans out. Mark, is there anything else in the pipeline for you that you’d like to mention.
[00:27:36.690] – Professor Mark Tomlinson: As you’ve probably gathered from what I’ve been saying, and I’m the Co-director of the Institute for Life Course Health Research, we’re really trying to understand the complexities of these pathways. Also in this other cohort I mentioned, we just submitted a grant again to follow them up when they’re age 12 and 14, and to try and understand how potentially the massive early adversities of these children and their lives could potentially if you follow them into early adolescence, we know that adolescence is often quite an important second chance where if caregivers are able to be with their children in their relationship and monitor them and be responsive and not engage in harsh discipline, that that can actually improve the resilience of those children quite enormously, even if you weren’t seeing that very early on.
[00:28:32.780] So we’re trying to get some funding too, to have a look at that in another sample. So again, just to try and understand some of the complexities of these pathways.
[00:28:42.930] – Jo Carlowe: Really interesting and potential cause for optimism. Mark, finally, what’s your takeaway message for those listening to our conversation today?
[00:28:52.770] – Professor Mark Tomlinson: I think it probably goes from one of your previous questions is that early intervention is an absolutely necessary condition, but it’s not a sufficient one and we need to think about what we need to do later to build on what we achieve early.
[00:29:08.590] – Jo Carlowe: Brilliant. Mark, thank you so much. For more details on Professor Mark Tomlinson please visit the ACAMH website, www.acamh.org and Twitter at @acamh. ACAMH is spelt A-C-A-M-H and don’t forget to follow us on your preferred streaming platform. Let us know if you enjoyed the podcast with a rating or review and do share with friends and colleagues.