Children bullied by siblings three times more likely to develop psychotic disorder

Children who are bullied by their siblings are up to three times more likely to develop psychotic disorders such as schizophrenia when they become adults, according to new research.

The study by Warwick University is the first of its kind to explore the links between sibling bullying and the development of psychotic disorders.

Nearly 3,600 children from Avon Longitudinal Study of Parents and Children gave details of sibling bullying at the age of 12 and then filled in a clinical test assessing psychotic symptoms when they were eighteen years old.

At the age of 12, 664 had experienced sibling bullying, 486 children were bullies to their siblings and 771 children were bully-victims (victimized by siblings and bullied their siblings). Fifty-five of the total 3,600 children in the study had developed a psychotic disorder by the age of eighteen.

Senior author Professor Dieter Wolke from the University of Warwick’s Department of Psychology, said: “Bullying by siblings has been until recently widely ignored as a trauma that may lead to serious mental health problems such as psychotic disorder.

“Children spend substantial time with their siblings in the confinement of their family home and if bullied and excluded this can lead to social defeat and self-blame and serious mental health disorder as shown here for the first time.”

The researchers found that the more frequently children are involved in sibling bullying, either as bully, victim, or both, the more likely they were to develop a psychotic disorder. Those involved in sibling bulling, as bully or victim, several times a week or month are two to three times more likely to develop a psychotic disorder than other kids.

Children bullied both at home and by school peers are even worse off – being four times more likely to develop psychotic disorders than those not involved in bullying at all.

First author Slava Dantchev, from the University of Warwick, added: “If the bullying occurs at home and at school the risk for psychotic disorder are even higher. These adolescents have no safe place.

“Although we controlled for many pre-existing mental health and social factors it cannot be excluded that the social relationship problems may be early signs of developing serious mental health problems rather than their cause.”

The researchers want parents and health professionals to be made aware of the long-term mental health consequences that sibling bullying may have and wants to see interventions developed to reduce and even prevent this in families.

Psychotic disorders such as schizophrenia or bipolar disorder cause abnormal thoughts and perceptions, and often involve hallucinations or delusions. Sufferers experience severe distress and changes in behaviour and mood and have an increased risk of suicide and health problems.

The research, ‘Sibling bullying in middle childhood and psychotic disorder at 18 years: A prospective cohort study’ was published in Psychological Medicine.

The research was supported by the NIHR Bristol Biomedical Research Centre.