Obese Children as Young as 7 At Risk of Developing Depression: ECO 2019

Dr Charlotte Hardman


April 30, 2019

My name is Dr Charlotte Hardman. I'm a senior lecturer in psychology from the University of Liverpool in the UK. And I'm here at the European Congress on Obesity in Glasgow to present our latest research on childhood obesity and mental health symptoms.

How did you go about your study?

We used data from the Millennium Cohort Study. This is a large population based cohort from the United Kingdom. It's children who were born between 2000 and 2002, and they've been followed up ever since. So this provides a very rich source of data. We used data from just over 17,000 children from this cohort, and we looked at assessments between the ages of 3 right up through to 14. And what we were interested in was their levels of obesity, and also their levels of mental health symptoms, which we call internalising symptoms - that's basically mental health, anxiety, depression and withdrawal symptoms.

We were interested in the extent to which obesity and internalising symptoms might occur and develop together. Because we know that mental health problems and obesity are increasing in children and adolescents, but we don't know very much about how they might be associated with each other, and how they might develop together.

So that was the overarching aim of our study was to answer that question, and also look at the temporal precedents of these two health outcomes over childhood and adolescence.

So here we were trying to answer the question, what comes first? Is it obesity preceding mental health, or is it the other way around?

What were your findings?

The key finding was that we didn't find a great deal of association between mental health and obesity before the age of 7. Once the children got to the age of 7, here we saw that obesity and internalising symptoms were more likely to occur together, and there was also an association in their rate of development. So increases in one over time was associated with an increase in the other. And what we also saw emerging from the age of 7 was a bi-directional association. So that we found that obesity predicted later risk of developing high internalising symptoms, but high internalising symptoms were also a risk factor for later obesity.

So this indicates that what we're seeing here is a bi-directional association where one is associated with the other.

Were you expecting children to be affected at such a young age?

That was quite surprising. We know that obesity levels do increase as children get older and into adolescence. And that's also the same for mental health. There has been one previous study, which similar to what we found, suggested that associations did start to emerge in later childhood.

And there’s quite a lot reasons why that might be. We weren't able to tell that from our study. But it could be that perhaps as children are getting older, they're becoming a bit more aware about body weight. Unfortunately, having a higher body weight is highly stigmatised in our society. And there is some evidence from other studies that as children get older, they become more aware of this. And they start to internalise this, this bias about weight and this can affect self-esteem, and can potentially lead to depressive symptoms. So you can see how potentially they could be linked by that particular mechanism.

Were some groups of children at a higher risk than others?

That’s a really interesting question. What we did do with the data is we looked at factors which could explain the association and one obvious one is socio-economic position.

We know from previous research that children from disadvantaged backgrounds are more likely to have obesity, and they're also more likely to have mental health problems.

So it's possible actually socio-economic position could explain, and in fact confound, any relationships that we might find. So that's an important part of our study, was that we controlled the socio-economic position. And when we did this, we saw that the associations between obesity and internalising symptoms did become a bit weaker.

But we did still find that there were unique associations, even after we'd controlled for socio-economic position. And that's important because it suggests that there are other factors at play here. And these might be psychological, social, or physiological factors. So, essentially socio-economic position partly explained some of the association, but it wasn't the only factor.

How might your findings be used in practice?

So I think what our study does is highlight the complexity of obesity. So I think some people might think that obesity, it’s just about eating less and doing more exercise, and what could be simpler. And I think our study really challenges that and shows that there is this link with mental health.

And this link starts to develop from the age of 7 onwards. And I think that's very important for anybody who's working with children who have obesity to really understand this, this link with mental health. So if a child is struggling with their weight, it's also increasingly likely they'll be struggling with their mental health. And that does have implications for the sorts of treatment approaches we might employ, and I think really emphasises that weight needs to be treated extremely sensitively, when we're working with young people.


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