Researchers said the effects of bullying were as serious as sexual or physical abuse by an adult or childhood neglect.
A major long-term study found children who were bullied were more likely to experience depression, anxiety, suicidal thoughts and poor physical health when they were 50-years-old than those who had not been victimised.
Senior author, Professor Louise Arseneault, from the Institute of Psychiatry at King’s College London, said: “When we compared the effects to other childhood adversities such as being put in care, abuse by an adult or neglect, it is of the same scale. It is should be put in the same bracket.
“Some children will be set on a pathway towards problems for the rest of their lives. We need to take bullying seriously and do all we can to prevent it and help those children when it does happen.”
The British National Child Development Study includes data on all children born in England, Scotland and Wales during one week in 1958.
A team at King’s College London examined data on 7,771 children whose parents provided information on their child’s bullying when they were aged seven and 11.
More than one in four had been bullied occasionally and around one in seven frequently.
They then underwent several tests throughout their lives and gave feedback on their own health.
At age 50 they were less likely to have qualifications, less likely to live with a spouse or partner and have less social support.
Those who had been bullied had lower scores on a word memory test designed to measure cognitive IQ even when their childhood intelligence levels were taken into account.
Prof Arseneault said: “Previous studies have shown that bullying really gets under the skin and affects the biology at a cellular level. The word recall test indicates bullying victims were showing signs of early ageing. We are conducting further research to push this finding further.”
It was also found people who were bullied as children were more likely to report that they had poor health.
The study said that due to the techniques used to measure mental and physical health it is likely their findings are an underestimate of the long-term effects of bullying.
Dr Ryu Takizawa, lead author of the paper from the Institute of Psychiatry at King’s College London, says: “Our study shows that the effects of bullying are still visible nearly four decades later.
“The impact of bullying is persistent and pervasive, with health, social and economic consequences lasting well into adulthood.”
The researchers said in the American Journal of Psychiatry that bullying may trigger a cycle of victimisation that lasts a lifetime.
Barbara Macintosh, of the Mental Health Foundation and the Children and Young People’s Mental Health Coalition, said we know what can help children but it is not happening in practice.
She said: “This is a shocking report, it shows how really serious the effects of bullying are It is so unnecessary for adults to be suffering in their 50s from events in school.
“We hope this will be a catalyst to spur action.
“We would like to see all schools and children’s organisations have a much clearer and more systematic approach to dealing with bullying.”
Prof Dieter Wolke, Professor of Developmental Psychology at the University of Warwick Department of Psychology, this was an important study which should be taken seriously by schools, communities and the health service.
He said: “By the time a child turns 18 they will have spent many more hours with peers than with their parents yet peers are often overlooked when someone is in distress, they are always asked about their relationship with their parents.
“Children don’t dress like their parents or listen to the same music as them – their peers are a much more important influence than has been realised. It is a terrible thing to be excluded by your peers.”
He said parents should be alert to bullying between siblings as this often translates to school and not be too harsh in their parenting or to overprotective as this discourages children from reporting bullying.
Health professionals must also be alert to physical signs of distress that could have their roots in bullying, such as persistent headaches or stomachaches which children often report when they are anxious.
He said: “Parents should always talk to their child before they go running to the school. And help your child make friends, let them have sleepovers and things like that, because having friends protects against victimisation.”
Emma-Jane Cross, chief executive and founder of BeatBullying, said: “With current generations facing even greater threats from cyberbullying and trolling than those in the study, we can only assume that the consequences of bullying could be even more damaging for future generations.
“We need an urgent review of how bullying and cyberbullying is tackled in this country led by an anti-bullying tsar – covering the role of industry, schools and Government, and ensuring that children who are bullied receive the counselling support they desperately need.”