In this Papers Podcast, Dr. Umar Toseeb discusses his JCPP paper ‘Genetic influences on sibling bullying and mental health difficulties’ (https://doi.org/10.1111/jcpp.13956).
There is an overview of the paper, methodology, key findings, and implications for practice.
Discussion points include:
- Insight into the dataset used in the study (Avon Longitudinal Study of Parents and Children).
- The reason behind the focus on sibling bullying and the prevalence rates of sibling bullying.
- Sibling bullying and genetic risk for mental health difficulties as additively associated with mental health difficulties.
- The lack of moderation effect of genetic risk for mental health difficulties on the relationship between sibling bullying and mental health difficulties.
- Insight into the ‘Diathesis stress model’.
- Sibling bullying and mental health difficulties as co-occurring, in part, due to shared genetic influences.
- Potential implications of the research.
In this series, we speak to authors of papers published in one of ACAMH’s three journals. These are The Journal of Child Psychology and Psychiatry (JCPP); The Child and Adolescent Mental Health (CAMH) journal; and JCPP Advances.
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Dr. Umar Toseeb is a Senior Lecturer in Psychology in Education at the Department of Education, University of York. Umar uses behavioural and genetic data from existing population based datasets to understand special educational needs and mental health in childhood and adolescence.
Transcript
[00:00:00.157] Mark Tebbs: Hello, and welcome to the Papers Podcast series for the Association for Child and Adolescent Mental Health, or ACAMH for short. I’m Mark Tebbs, a Freelance Consultant. In this series, we speak to the authors of papers published in one of ACAMH’s three journals. These are the Journal of Child Psychology and Psychiatry, commonly known as JCPP, the Journal of Child and Adolescent Mental Health, known as CAMH, and JCPP Advances.
If you’re one of our fans of our Papers Podcast 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.
Today, I’m delighted to be talking to Dr. Umar Toseeb, who is the lead author of the JCPP paper, “Genetic Influences on Sibling Bullying and Mental Health Difficulties.” Umar, delighted to be speaking to you, so if we can start with some introductions, maybe, could you tell us about yourself, your career to date?
[00:00:58.143] Dr. Umar Toseeb: Absolutely. Thank you, Mark, and thank you for having me. So, I’m a Senior Lecturer in Psychology in Education at the University of York. My background is psychology, so my undergraduate degree and my PhD are in psychology. And I’ve worked in various academic departments in the past, so psychiatry, psychology, language and communication sciences in – before joining the Education Department here at York about six years ago. And in terms of my research, I tend to use existing population-based datasets to understand special educational needs and mental health during childhood and adolescence.
[00:01:28.548] Mark Tebbs: Great stuff. Really looking forward to the podcast today. It’s an opportunity for you to give a little bit of a namecheck of the colleagues you worked with on the paper.
[00:01:35.783] Dr. Umar Toseeb: Oh, yeah, absolutely. So, the first one is John Vincent, who’s currently at King’s College London, at the moment, and a fantastic Behaviour Genetics Analyst. He did lots of the technical analysis, which I wouldn’t be able to have done, so fantastic to have him onboard with us. And, also, Kathryn Asbury, who’s at the University of York, friend and longtime collaborator, with lots of expertise in behaviour genetics. So, again, she’s a fantastic asset on this paper, so a great team all round.
[00:01:59.840] Mark Tebbs: Excellent. So, let’s turn to the paper, could you just give us a brief overview of the paper for our listeners?
[00:02:06.703] Dr. Umar Toseeb: Yeah, so we used data, so existing data, from the Avon longitudinal study of parents and children, ALSPAC, and I think that there’s lots of papers in JCPP where they’ve used ALSPAC data, so I’ll just go over it very quickly. It’s a longitudinal cohort study of children born in the early 90s, and then they were followed up through their life, and I think they are, I don’t know, late 20s, early 30s, at the moment.
So, as part of the study, the children provided genetic data, and then they answered questions around sibling bullying, when they were about 12 years old. These included questions around physical bullying, so hitting, verbal bullying, saying nasty things, and psychological bullying, being excluded from activities. And they were asked about being the victims of bullying, but, also, perpetrators of bullying against their siblings. And then their parents completed some scr – mental health difficulty screeners around the same age, so late childhood, early adolescence.
And then, using the children’s genetic data, we calculated two sets of polygenic risk scores, which are indices of genetic risk, which capture some, but not all, genetic propensities. So, we calculated one for depression and one for ADHD. We felt that those were reasonable indices of genetic risk, because they cover both emotional difficulties and social difficulties, and given that our outcome variables were emotional difficulties, conduct problems and hyperactivity, it just seemed like the right indices to use.
In terms of our findings, I’ll just go through them, and then we can talk a bit more about them as we progress. So, we found that being the victim or perpetrator of sibling bullying is associated with poorer mental health. That wasn’t surprising. We found that in previous research, and other Researchers have found that too. We also found that genetic risk for common mental health difficulties is associated with emotional problems, conduct problems and hyperactivity, and, again, we’d expect to find that. Other people have shown that in other research, and we’ve confirmed that here.
We found that the effects of sibling bullying and genetic risk on mental health difficulties were additive. Meaning that genetic risk explained some variation in mental health difficulties, and then sibling bullying explained some additional variation in mental health difficulties. So they both explain some unique variants.
What we didn’t find was that those with high genetic propensity for mental health difficulties who were also involved in sibling bullying, they didn’t fare any worse, compared to those who had lower genetic propensity for mental health difficulties and involved in sibling bullying. And we expected to find that, and we’ll go into some more details about why we expected to find that, and why some of the reasons are for not finding that. And, finally, we also found that genetic risk for mental health difficulties also predicted sibling bullying, meaning that the two might co-occur because they are influenced by a common set of genetic factors.
[00:04:39.708] Mark Tebbs: Okay, brilliant, thank you for the overview. So, we’ll unpack some of this in stages. So, let’s talk a little bit more about the reason that you wanted to study the genetic influences on sibling bullying and mental health difficulties. I’m just curious whether there was a, kind of, particular gap in the research literature that you were aiming to address?
[00:05:00.703] Dr. Umar Toseeb: Yes, there was. So, lots of my previous research has focused on sibling bullying and its relationship with mental health difficulties, particularly during childhood and adolescence. So, we’ve looked at the relationship on a phenotypic level in the Millenium Cohort Study, which is a nationally representative UK birth cohort study, and, also, the Children’s World Survey, which is a cross-national study of children’s lives. And I think the reason we were specifically interested in sibling bullying is ‘cause often it’s seen as harmless and just a normal part of growing up. But we’re interested in bullying, and not just conflict and disagreement, which means that those negative behaviours need to be persistent. So, we were interested in persistent conflict, disagreements, violence, and we defined that as about once a week or more, and that’s quite typical in the sibling bullying literature.
And what we found was that about one in four children report being bullied by their siblings, so being hit, kicked, etc., at least once a week. But one in five reported bullying their siblings, and then there was some overlap between the two, meaning about half of the children who were bullying their siblings were also being bullied by their siblings. And those prevalence rates vary, depending on country, depending on the characteristics of the child, so you might find that some children who are particularly vulnerable, like autistic children are more likely to be involved.
Now, to your question around why genetics? Well, when reading the literature on this, and I’m guilty of this too, I felt that lots of Researchers pushed the narrative that sibling bullying causes mental health difficulties. And that is one possibility, but there are other possibilities, as well, and we wanted to explore and investigate some of the other possibilities. So, it could be that experiencing mental health difficulties might make some children more susceptible to being bullied by their siblings, or bullying their siblings, or that sibling bullying and mental health difficulties are caused by, or influenced by, a third unmeasured factor.
Now, the third unmeasured factor that we were interested in, that could be influencing both sibling bullying and mental health difficulties, was genetics, and that’s what we looked at. But it could be other things as well, so poverty could be one, and we know that in some studies poverty is a predictor of sibling bullying, and we also know poverty is a predictor of poor mental health. So, the point that I’m trying to make is, sibling bullying and mental health difficulties might be related because they are influenced by this third factor, and we investigated genetics, and genetics was the way we tried to figure out the direction of some of these effects.
The idea is not novel, so I don’t want to sit here and be like, “I’m the genius who came up with this,” I’m not. It’s been tested previously, but it’s been tested in peer bullying, so we felt that it needed to be done in sibling bullying, because some of the predictors and the correlates and the environments, motivations, where sibling bullying happens is different, compared to peer bullying, so we needed to test that specifically.
[00:07:44.148] Mark Tebbs: Okay, right, yeah. So, how did you go about trying to test that? I imagine that there was some challenges to, kind of, get underneath that. So, how did you go about the study? Were there any methodological challenges? And are there, kind of, going through that explanation, are there any research limitations that you’d like to share with the listeners?
[00:08:05.779] Dr. Umar Toseeb: So, as I mentioned, it was a secondary analysis of existing data, so we’re somewhat limited by the data that was already collected. So, children were asked about sibling bullying experiences at the age of 12 years, and they self-reported those, and then the mental health difficulties were a parent measure, and one was taken at the age of 11 years, and one was taken at the age of 13 years.
And that’s slightly problematic, because we say that this study is cross-sectional, but, actually, the measure of mental health was not taken at the same time as the measure of sibling bullying. We just aggregated the year before with the year after, and then assumed that it’s, kind of, 12 years old and it’s the same as sibling bullying, but, actually, it’s not. And the reason that’s problematic is because it doesn’t actually tell us what the child was feeling or experiencing at the time they were being bullied or doing the bullying, but it was the best that we could do with the data that we had. So, I suppose that’s one of the drawbacks.
The other one is that polygenic scores are good, because they capture some genetic effects, but they’re not able to capture all genetic effects, and I don’t think anybody claims that they do. So, when we think about some of these genetic effects, we just have to bear in mind that we’re not able to capture all genetic effects with these polygenic scores, they only capture a limited amount of genetic effect.
And the final one I think that methodologically that is particularly relevant here, and I know that lots of people have done it before, where you talk about the limitations of your sample and it not being representative. And one of the problems with the ALSPAC sample is that it’s predominantly white and quite affluent. And this is particularly relevant for our study, because genetic effects are different for different populations. So, our findings might only really apply to a white, Northern European population, and might not hold if a similar study was done in an Asian population, or an African ancestry population. So, we’ve done the best we can with the dataset that we have, but we are aware that there are some limitations.
[00:09:55.788] Mark Tebbs: Yeah, brilliant, thank you for that. So, let’s turn to the findings then. So, the first finding was that both sibling bullying and genetic risk for mental health difficulties are additively associated with mental health difficulties. And then, secondly, that the genetic risk for mental health difficulties doesn’t moderate the relationship between sibling bullying and mental health difficulties. So, could you explain these and, kind of, what the implications of these findings are?
[00:10:23.663] Dr. Umar Toseeb: So, I’ll do the first one, which is additive effects. So, in terms of additive effects, I suppose at a group level, what it suggests is that if we want to understand mental health difficulties, in relation to sibling bullying, then we also need to consider genetic risk. And the reason why we need to test this specifically is because sometimes you might expect a genetic effect might be masked by an environmental effect. So if you don’t include genetic risk in your statistical models and then you find that an environmental stressor predicts mental health difficulties, but once you include genetic risk, that environmental stressor might not predict mental health difficulties.
Whereas, here, what we’re finding is even when you include a genetic risk factor and include the environmental stressor, which is sibling bullying, then sibling bullying is still associated with mental health difficulties, even after controlling for some genetic risk. And the reason that’s important is because within this context, it suggests that both genetic and environmental triggers, so sibling bullying, are associated with mental health difficulties, so they are both important.
Secondly, in terms of lack of moderation effect, this was surprising. We thought that children with high genetic risk for mental health difficulties who experienced sibling bullying would fare worse compared to those with low genetic risk for mental health difficulties who experienced sibling bullying. We expected this because how children respond to environmental stressors might differ based on their genetic propensities, specifically, the diathesis-stress model says that children’s responses to the environmental stressors, in our case, sibling bullying, is dependent on their predisposition, in our case, genetic risk. So, that’s why we expected to find an effect, a moderation effect, but we didn’t.
And I can think of probably three reasons why we didn’t find an effect. Firstly, it could just be because there isn’t an effect, and genetic risk for mental health difficulties just doesn’t moderate the relationship between sibling bullying and mental health difficulties. So that’s a real possibility, we didn’t find a moderation effect because there isn’t a moderation effect, and the theory that we were trying to test just doesn’t hold.
The alternative explanation is that polygenic scores in itself is not a great measure, and it doesn’t capture genetic risk adequately. And, again, I think that’s a real possibility, there’s been other research studies where polygenic scores have been used to test moderation effects with relation to environmental stressors and mental health difficulties and they don’t find effects. So, it might be that the measure of polygenic scores just isn’t great.
And the third one is that we were just underpowered. Like, we had a few thousand kids in the study, but maybe for genetic research, larger sample sizes would give you more power to find an effect, and I think in this instance, we might have been underpowered to find an effect. So, we didn’t find any moderation effect, and those are some of the reasons why.
[00:12:53.108] Mark Tebbs: Okay, thank you. So, you mentioned the diathesis-stress model, could you tell us a little bit more about that?
[00:12:59.120] Dr. Umar Toseeb: So, the diathesis-stress model, if you have a child with a high genetic propensity for mental health difficulties, you would expect, according to the model, that child to require less environmental stressors for the mental health difficulty to manifest, because they’ve already got high levels of genetic risk. But if a child has low levels of genetic propensity for mental health difficulties, then the environmental stressor would need to be higher, according to this model, but we didn’t find any support for that model in this study.
[00:13:27.188] Mark Tebbs: Okay, brilliant, thank you. So, you also found that sibling bullying and mental health difficulties co-occur, partly due to the shared genetic influences. So, could you explain that to us?
[00:13:40.783] Dr. Umar Toseeb: The reason we wanted to look at this was because, going back to the point I made earlier on, is I feel like, when I’m reading the literature, lots of people make this assumption that mental health difficulties are caused by bullying, whether that’s sibling bullying or whatever. And in this case, we wanted to explore other possibilities, and our findings suggest that there are three possible explanations. So, we don’t actually confirm which one it is, but our model suggests that it’s one of these three, or, more likely, a combination of the three.
And these are: genetic risk for mental health difficulties increases the risk of experiencing mental health difficulties, and then, when a child experiences mental health difficulties, they are more likely to be bullied by their siblings. The second explanation might be that genetic risk for mental health difficulties increases the risk of being bullied by siblings, or bullying siblings, which then leads to mental health difficulties. And the third explanation is that we know that genes are generalist, meaning that the same set of genetic variants might explain different phenotypic variable or outcomes.
So, part of the reason why sibling bullying and mental health difficulties co-occur is because the same set of genetic variants influence both sibling bullying and mental health difficulties, somewhat independently. So, I suppose what the findings show is that even after accounting for some genetic effect, sibling bullying and mental health difficulties are still related, leaving open the possibility that sibling bullying leads to mental health difficulties, or that mental health difficulties leads to sibling bullying.
[00:15:03.308] Mark Tebbs: Brilliant, that’s really clear, thank you. So, what are the potential implications of the research?
[00:15:09.223] Dr. Umar Toseeb: I think the potential implications of this piece of work are a few steps removed from practice. So, other Researchers need to build on these findings, and trying to figure out the three possible directions of these effects that I just mentioned. But I suppose once we’re at the point where the pathways between sibling bullying and mental health difficulties are clearer, it could inform interventions to reduce both types of difficulties.
So, for example, if it becomes clear that experiencing mental health difficulties does lead to higher rates of sibling bullying, then trying to alleviate mental health difficulties might also reduce the prevalence of sibling bullying. I think we’re a bit far from that, and a few steps removed, and I think more research is needed, but I imagine, ultimately, that’s probably what we’re aiming for.
[00:15:48.828] Mark Tebbs: Are you carrying on this research? Are you doing more research in the area?
[00:15:52.623] Dr. Umar Toseeb: Yeah, so I like doing research on sibling bullying, because it’s interesting, and, also, surprisingly, there aren’t that many Researchers who focus on it, so it gives me free rein, to some extent, to do what I want. But in terms of the specifics, I want to extend my research on sibling bullying on an international context, for some of the reasons I spoke about earlier, as in the genetic effects will differ depending on the context and the country and the cultural context, etc., and, also, the prevalence of sibling bullying differs, so the correlates will be different. So, I think I’m interested in trying to extend this into diverse world contexts, and we’ve already started some of that work.
I’m also interested in thinking about intergenerational transmission of sibling bullying. So, I’m planning a piece of work around how sibling bullying behaviours might be passed down and transmitted from parents to children, and trying to figure out how I could do that and who might fund that.
[00:16:41.508] Mark Tebbs: Wow, brilliant, it’s such a interesting, important area of research. Look, we’re coming to the end of the podcast, so is there a final take home message?
[00:16:51.063] Dr. Umar Toseeb: I think there’s a broader take home message around sibling bullying, which is that I hope that our work continues to highlight that sibling bullying is just not acceptable, and it’s not a normal part of growing up. So, for a child to be hit or called names or made fun of, etc., at least once a week by someone they live with is quite a serious problem. We wouldn’t tolerate it at school, or in a workplace, so it shouldn’t be acceptable at home.
[00:17:13.228] Mark Tebbs: Brilliant, thank you so much, it’s been a really interesting conversation. So, for more details on Dr. Umar Toseeb, please visit the ACAMH website, www.acamh.org, and follow us on Twitter @ACAMH. ACAMH is spelt A-C-A-M-H. Please don’t forget to follow us on your preferred streaming platform, let us know if you enjoy the podcast, with a rating or review, and do share with friends and colleagues.
