Mental health

Bullied children more likely to self-harm

“Children bullied during their early years are up to three times more likely to self harm than their classmates,” BBC News has reported.

The news is based on a study that assessed whether children were bullied at several points during childhood, as well as whether they had self-harmed in the months before their 12th birthday. The research followed over 1,000 pairs of twins from the ages of 5 to 12, and interviews with their mothers suggested that 3% of the children (62 children) had self-harmed by age 12. Just over half of these (35 children) had experienced frequent bullying, according to accounts by the children or their mothers. The researchers calculated from this that children who were frequently bullied had around double the risk of self-harming as those who had not reported bullying.

Although this study has identified an association between bullying and self-harm, it is difficult to prove that bullying directly causes self-harm. For example, it is not certain that the bullying definitely preceded self-harming behaviour. The relationship between bullying and self-harm is likely to be complex and could involve other factors, some of which the researchers attempted to take into account.

Although the study cannot tell us the exact nature of the relationship between bullying and self-harm, it does highlight the importance of giving victims of bullying care and support to cope with the possible emotional and psychological effects.

Where did the story come from?

The study was carried out by researchers from King’s College London and other institutions in the UK and US. It was funded by a number of organisations, including the Medical Research Council. The study was published in the peer-reviewed British Medical Journal.

This study was briefly reported in the Metro, whose headline – “Bullies ‘make children self-harm’” – suggests the study’s results were more conclusive than they really were.

What kind of research was this?

The authors of this research say that 25% of UK children report being bullied. They wanted to see whether bullying was associated with an increased risk of self-harm during adolescence. To examine the issue, the researchers analysed data from a cohort study, called the Environmental Risk (E-Risk) study, which was designed to look at how genetic and environmental factors affect childhood behaviour. This analysis of the E-risk looked at the development of 1,116 same-sex twin pairs (2,232 children) who were born in England between 1994 and 1995. Half of the twin pairs in the study were identical.

A cohort study is the best way to examine whether a particular exposure (in this case bullying) increases an individual’s risk of a particular outcome (self-harm). In this particular study, the mothers were questioned about whether their child had been bullied at ages 7 and 10, and the children were asked at age 12 whether they had been bullied. Mothers were asked whether their children had self-harmed by the time they were 12. Therefore, it is difficult to say that bullying (the exposure) definitely preceded self-harm (the outcome). This is particularly the case when looking at how self-harm related to the children's own report of bullying (rather than the mothers'), as both measures were assessed only at age 12. Self-harm could be a sign of low self-esteem or unhappiness, which in turn may make a person a target for bullies.

What did the research involve?

The E-Risk study started in 1999-2000, so carried out its first assessment when the children in the cohort were five years old. They were next followed up at the ages of 7, 10 and 12 years. The follow-up rates were very high for all children in the cohort at all assessment stages.

Bullying was assessed by interviewing mothers when the children were 7 or 10, and interviewing the children themselves at age 12. The researchers explained to the mother or child that:

“Someone is being bullied when another child says mean and hurtful things, makes fun, or calls a person mean and hurtful names; completely ignores or excludes someone from their group of friends or leaves them out of things on purpose; hits, kicks, or shoves a person, or locks them in a room; tells lies or spreads rumours about them; or does other hurtful things like these. We call it bullying when these things happen often and it is difficult for the person being bullied to stop it happening. We do not call it bullying when it is done in a friendly or playful way.”

When bullying was reported, the interviewer asked the mother or child to describe what happened. An independent reviewer verified that the experiences documented related to instances of bullying. Mothers’ and children’s narratives of bullying experiences were coded as “never”, “yes but isolated incidents”, or “frequently”. Children were also asked directly if they had been bullied “a lot”.

When the children were 12, mothers were asked at an interview whether each twin had deliberately harmed themselves or attempted suicide in the previous six months. Mothers who responded yes to this question were asked to provide a description of what took place. The researchers say they only asked mothers and not children because of ethical considerations.

Other possible confounding factors that were taken into account during the researchers’ analyses were mothers’ reports that their children had been exposed to maltreatment (physical or sexual harm by an adult before age 12), behavioural problems at age five, and child’s IQ at age five. They also looked at socioeconomic factors.

What were the basic results?

Of the cohort, 16.5% (350 children) were reported by their mothers to have been “frequently” bullied before age 10, and 11.2% of children (237 children) reported that they had been bullied “a lot” before age 12. Of the cohort, 2.9% (62 children) were reported by their mothers to have self-harmed in the previous six months by age 12, of which 56% (35 children) were victims of frequent bullying.

After adjustment for confounders:

  • Frequent bullying by age 10 (as reported by mothers) was associated with an almost double chance of a mother reporting that her child had self-harmed by age 12 (relative risk [RR] 1.92, 95% confidence interval [CI] 1.18 to 3.12).
  • Frequent bullying (as reported by the child) by age 12 was associated with a more than double chance of their mother reporting that the child had self-harmed by age 12 (RR 2.44, 95% CI 1.36 to 4.40).

Looking at children who were bullied, the researchers also found that those who self-harmed were more likely than those who had not self-harmed to have a family history of attempted or completed suicide, to have experienced physical maltreatment by an adult, or to have other mental health problems.

How did the researchers interpret the results?

The researchers concluded that prevention of self-harm in young adolescents “should focus on helping bullied children to cope more appropriately with their distress”. They also said that particular focus should be given to children who have additional mental health problems, have a family history of attempted or completed suicide, or have been maltreated by an adult.


This valuable study found that over half of children who had reportedly self-harmed at age 12 had also reportedly been exposed to frequent bullying in the past. Its strengths include the fact that children were only selected from those born between 1994 and 1995, so it representated the UK population with newborns at that time, and that children were followed over a period of time. However, although this study shows an association between bullying and self-harm, it is difficult to prove that bullying directly causes self-harm:

  • Past bullying was asked about at ages 7, 10 and 12, and mothers were asked whether the child had self-harmed in the past six months at age 12 but not about whether self-harm had happened before this. Therefore, it is difficult to say whether bullying definitely preceded self-harm in all cases or that a child had never self-harmed before they were bullied.
  • Though the researchers attempted to adjust for factors that could be associated with both the risk of bullying and risk of self-harm (such as maltreatment and behavioural problems), the relationship between these experiences is likely to be complex. Many other factors could be inter-related, and it is difficult to tease these factors apart. The study found that bullied children who self-harmed were more likely to have been maltreated, to have a history of suicide in their family, or to have current mental health problems.
  • Bullying was reported by interviewing mothers at two of the three assessments, and self-harm was reported by mothers only. Many children may be reluctant to report either of these occurrences, to their mothers or to researchers. Therefore, the responses in these interviews may not fully reflect the prevalence of bullying or self-harm.
  • Bullying may mean different things to different people. It can take many forms, such as physical, emotional, financial or discriminatory, and some children or mothers may not define bullying in the same way. For example, what they consider to be “done in a friendly or playful way” may differ, and some people may not consider isolating someone to be bullying in the way that violence or teasing might be.
  • Only 62 of the entire cohort reported self-harming and 35 reported being frequently bullied. Calculating risk associations from such small numbers may make the risk figures less reliable. The researchers note that their findings need to be replicated in larger groups of children.
  • This study only looked at an association between self-harm and bullying. It cannot tell us whether there is also an association between self-harm and children who bully others.
  • The study included only twins, and the results may not be representative of non-twins.

Despite its limitations, this study highlights an association between self-harm and bullying in children, both serious concerns that need to be addressed. Further research will help confirm whether this association holds true in larger groups, and whether this information can help identify children at risk of self-harm and target them for support.

NHS Attribution