The effects of constantly being bullied are more than just psychological. Research now shows that there may be physical structural differences in the brains of adolescents who are regularly victimized, and this could increase the chance that they suffer from mental illness. This is the conclusion of a study in the journal Molecular Psychiatry which is published by Springer Nature. The research was led by Erin Burke Quinlan of King's College London in the UK and is the first to show that chronic peer victimization during adolescence impacts mental health via structural brain changes.

Burke Quinlan and her colleagues analyzed data, questionnaires and brain scans of 682 participants from England, Ireland, France and Germany. These participants were part of the IMAGEN long-term project that assessed the brain development and mental health of adolescents. As part of this project, high resolution brain scans of participants were taken when they were 14 and 19 years old.

At the ages of 14, 16 and 19 these participants also had to complete questionnaires about whether they had been bullied, and to what extent. Overall, the results showed that 36 of the 682 young people were found to have experienced chronic bullying. The data of these participants were compared with those of the others who had experienced less chronic/severe bullying. Changes in brain volume as well as the levels of depression, anxiety and hyperactivity at age 19 were taken into account.

The subsequent findings validate and extend the literature linking peer victimization with mental health problems. But the novel finding is that bullying is linked to decreases in the volume of parts of the brain called the caudate and putamen. These changes were found to partly explain the relationship between high peer victimization and higher levels of general anxiety at age 19.

"Although not classically considered relevant to anxiety, the importance of structural changes in the putamen and caudate to the development of anxiety most likely lies in their contribution to related behaviours such as reward sensitivity, motivation, conditioning, attention, and emotional processing," explains Burke Quinlan.

She says it is worrying that as much as 30 per cent of young people could be victimized in one way or another by their peers, with some having to endure such treatment on an almost daily basis. Burke Quinlan emphasizes that adolescence is not only a time of new experiences and stresses, but also a period of extensive brain development. Therefore, she recommends that every effort should be made to limit bullying before it becomes a severe problem that might lead to changes in a young person's brain and the development of mental health issues.

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Reference: Burke Quinlan, E. et al (2018). Peer victimization and its impact on adolescent brain development and Psychopathology, Molecular Psychiatry DOI: 10.1038/s41380-018-0297-9