KEY POINTS:
A study provides strong evidence that being bullied can cause children to develop depression and anxiety.
Among identical twin pairs in which one experienced bullying between the ages of 7 and 9 and the other did not, the bullied twin was significantly more likely to have symptoms of
internalising problems at age 10, Dr Louise Arsenault of King's College, London, and her colleagues found.
Internalising problems are psychological problems in which negativity is directed inward towards the self, such as depression, as opposed to outwardly, such as conduct disorder.
This research "really supports the assumption or the belief that being bullied is bad for children's health", Dr Arsenault said.
And the fact that children were having these symptoms - which include frequent crying, fear of being alone, and stomach aches - at such a young age strongly suggested that they needed help, she added.
Bullied children are known to be more likely to have anxiety, depression and thoughts of suicide, as well as to experience social isolation, the team noted. But the question of whether bullying itself is the cause of these mental health problems remains open.
It's possible, the researchers explain, that bullying and mental health problems stem from the same risk factors, such as living in a poor neighbourhood or parental neglect, or even that a child with mental health problems is more likely to draw bullies' attention.
To investigate, Dr Arsenault and her team looked at 1116 twin pairs from a nationally representative sample of twins born in England and Wales between 1994 and 1995.
By looking at twins, Dr Arsenault said, they were able to account for the effect of family situation and environment, which could contribute to both bullying risk and the likelihood of having internalising problems, because the twins share the same family background and the same environment.
Among the 114 twin pairs in which one child was bullied and the other wasn't, according to reports from mothers and teachers, the bullied twin showed significantly more symptoms of internalising problems, such as worrying, being withdrawn, and feeling overly guilty.
Having such problems early in life increases a person's future risk of depression and anxiety disorders, Dr Arsenault and her team point out.
The findings show, she added, that efforts designed to fight bullying should not only address the bullies, but should also offer support to their victims.
"They need support," she said. "Their symptoms are to be taken seriously."
- REUTERS