Monday April 27 2015
Children may 'learn' anxious behaviour from their parents
The Mail Online has given stressed-out parents one more thing to worry about, saying: "Anxiety is 'catching' and can be passed on to children", adding that, "Attitudes of over-anxious parents can severely affect children's behaviour".
The study that prompted these headlines used an interesting "children of twins" study design intended to filter out the influence of genetics, which is known to have an effect on anxiety.
To do this, researchers studied patterns of anxiety in families of identical twins, who are genetically identical, and in families of non-identical twins.
They found there was some link between anxiety and neuroticism (a tendency to have negative thought patterns) in parents and their adolescent children.
There was no evidence that genetics was playing a significant role, but modest evidence that non-genetic factors were. This suggested that anxiety, far from being hardwired into DNA, might be passed on in other ways, such as through learned or mimicked behaviour.
In the Mail Online, journal editor Dr Robert Freedman said: "Parents who are anxious can now be counselled and educated on ways to minimise the impact of their anxiety on the child's development."
This suggestion seems a touch premature – as noted by the researchers, there is a chicken and egg situation here that has not been resolved. Do children worry because they sense their parents are worried, or do parents worry because they see their children are worried about something?
Family life is not always easy, but one way to boost your physical and mental health is to make the time to do activities as a family.
Where did the story come from?
The study was carried out by researchers from universities based in London, Sweden and the US. It was funded by the Leverhulme Trust, the US National Institute of Mental Health, and the National Institute for Health Research.
The study was published in The American Journal of Psychiatry, a peer-reviewed medical journal. It has been made available online on an open-access basis, so it is free to read or download as a PDF.
Generally, the Mail Online reported the story accurately, but hardly mentioned the study's limitations. The quote from journal editor Dr Robert Freedman saying that, "Parents who are anxious can now be counselled and educated on ways to minimise the impact of their anxiety on the child's development", seems a little premature, based on the relatively weak associations found in this research.
What kind of research was this?
This twin study investigated the relative role of genetic factors (nature) and non-genetic factors (nurture) in the transmission of anxiety from parent to child.
Non-genetic factors might be, for example, the children observing their parents' anxious behaviours and mimicking them, or the parenting style of anxious parents.
The researchers say it is well recognised that anxiety can run in families, but the underlying processes are poorly understood. This study wanted to find out whether genetics or environment was more important in the transmission of anxiety, by observing identical twins.
This type of study is commonly used for this type of question. It does not aim to pinpoint exact genes or non-genetic factors that play a role in a trait.
What did the research involve?
The team gathered self-reported anxiety ratings from parents and their adolescent children. They compared the results between identical twin families and non-identical twin families to see to what extent non-genetic factors were driving anxiety transmission, in contrast to genetics.
Data came from the Twin and Offspring Study of Sweden, which has information on 387 identical (monozygotic) twin families and 489 non-identical (dizygotic) twin families. A twin family comprised a twin pair where both twins were parents, each twin's spouse, and one of each of their adolescent children.
In families where the twins were identical, the cousins would share, on average, 50% of the same DNA with their (blood) aunt or uncle. In families where the twins were not identical, the cousins would share less of their DNA, on average, with their aunt or uncle.
If cousins whose parents are identical twins are more similar to their aunt or uncle for a trait than cousins whose parents are non-identical twins, this suggests that genes are playing a role.
Only same-sex twin pairs were used. Twin offspring were selected, so cousins were the same sex as one another and did not differ in age by more than four years, so they were as similar as possible. The average age of the twin offspring was 15.7 years.
This type of study design, known as a "children of twins" study, is intended to dampen down the potential influence that family genetics could have on the outcomes being investigated.
Anxious parental personality was self-reported using a 20-item personality scale. They rated phrases such as, "I often feel uncertain when I meet people I don't know very well", and, "Sometimes my heart beats hard or irregularly for no particular reason".
Each item was ranked between 0 (not at all true) and 3 (very true), covering social and physical signs of anxiety, as well as general worry. There was a similar self-reported scale to measure neuroticism.
Offspring anxiety symptoms – social, physical and general worry – were measured in a similar way, using questions from a Child Behaviour Checklist.
Both parents and offspring rated their anxiety and neuroticism over the last six months. The researchers used computer modelling of the relationships between individuals and their traits to estimate the contribution of genetic and non-genetic factors.
What were the basic results?
Analysis of the data suggested genetic factors were largely not driving the transmission of anxiety or neuroticism from parent to adolescent. Ratings of anxiety and neuroticism within and between twin families were only very weakly linked.
However, there was "modest evidence" that non-genetic transmission of both anxiety and neuroticism was happening. Although still a relatively weak relationship, it was statistically significant, unlike the genetic finding.
How did the researchers interpret the results?
The research team said their results supported the theory that direct, environmentally mediated transmission of anxiety from parents to their adolescent offspring was the main driver, and not genetics.
This study tentatively shows that environmental factors, as opposed to genetics, play a more important role in the transmission of anxiety from parents to their adolescent children.
However, it used self-reported anxiety ratings over a six-month period, so this tells us very little about any potential longer-term effects of anxiety transmission while growing up.
The correlations in the main results were quite weak. This means that not every adolescent with an anxious parent will "catch" or "take on" their parents' anxiety. This suggests that it's a more complex issue.
The results showed non-genetic (environmental) factors were more important than genetic, but precisely what these environmental factors were is not something this study can tell us.
The study used a clever and unique sample of twins and their families to drill down into the age-old debate about the influence of nature versus nurture. However, it doesn't prove that environmental factors are the main driver overall.
That notwithstanding, the authors suggest two main contrasting explanations for the results:
- parental anxiety causes their children to be more anxious – this could happen through different learning and mirroring behaviours known to occur when children and adolescents grow and develop; for example, an adolescent witnessing repeated examples of parental anxiety may learn that the world is an unsafe place that should be feared
- anxiety in the offspring influences the parenting they receive – the flipside is that a teenager showing anxious behaviour may cause their parents to worry; the research team add that this might in turn worsen the anxiety in the teenager, creating a negative feedback loop
This twin study doesn't bring us any closer to knowing which explanation might be true, or to what extent this can be impacted by changes in behaviour.
Despite these limitations, the hypothesis that children are sensitive to their parents' attitudes and mood seems plausible. So, learning more about how to manage your stress and feelings of anxiety could be good for both you and your children.
For more information and advice, visit the NHS Choices Moodzone.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.