People who are bullied during adolescence are much more likely to suffer with depression in early adulthood, a new study has found.

While depression is on the increase and bullying has been suggested as one possible cause, previous studies have failed to find a definitive link, so UK researchers decided to assess this further.

They carried out one of the largest studies on the possible link between being bullied as a teenager and suffering with depression in early adulthood. Almost 4,000 people were involved.

The participants filled in a questionnaire about bullying when they were 13 years old. At 18 years, they were assessed for depression.

Almost 700 of the participants admitted to being bullied more than once a week when they were 13 years old. Among these, almost 15% were depressed by the age of 18 compared to just 5% of teens who were not bullied.

Among those who had been bullied between one and three times over a six-month period, just over 7% were depressed by the age of 18.

The study also noted that 10% of those who had been frequently bullied suffered with depression for more than two years compared with just 4% of those who were not bullied.

The researchers said that when they took into account other factors which may have influenced the results, such as family issues and stressful life events, those who were frequently bullied still had a two-fold increased risk of being depressed by the age of 18 compared to those who were not bullied.

This finding was the same for both males and females. The most common type of bullying was name calling and in this study, most teenagers never told a parent or a teacher about it. However, three in four did tell an adult if they were physically bullied, e.g. if they were beaten up by someone.

According to the researchers from the University of Oxford, if this was a causal relationship, up to 30% of depression cases in early adulthood could be attributed to bullying during adolescence.

They said that while this is an observational study and no definitive conclusions can be made about cause and effect, it appears that bullying could be making a substantial contribution to the overall burden of depression, and interventions to reduce bullying in schools could reduce depression later in life.

Details of these findings are published in the British Medical Journal.

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