Sticks and stones may break your bones, but name-calling could actually change the structure of your brain.
A new study has found that persistent bullying in high school is not just psychologically traumatising, it could also cause real and lasting damage to the developing brain.
The findings are drawn from a long-term study on teenage brain development and mental health, which collected brain scans and mental health questionnaires from European teenagers between the ages of 14 and 19.
Following 682 young people in England, Ireland, France and Germany, the researchers tallied 36 in total who reported experiencing chronic bullying during these years.
When the researchers compared the bullied participants to those who had experienced less intense bullying, they noticed that their brains looked different.
Across the length of the study, in certain regions, the brains of the bullied participants appeared to have actually shrunk in size.
In particular, the pattern of shrinking was observed in two parts of the brain called the putamen and the caudate, a change oddly reminiscent of adults who have experienced early life stress, such as childhood maltreatment.
Sure enough, the researchers found that they could partly explain these changes using the relationship between extreme bullying and higher levels of general anxiety at age 19. And this was true even when controlling for other types of stress and co-morbid depressive symptoms.
The connection is further supported by previous functional MRI studies that found differences in the connectivity and activation of the caudate and putamen activation in those with anxiety.
"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 lead author Erin Burke Quinlan from King's College London.
In other words, the authors think all of this shrinking could be a mark of mental illness, or at least help explain why these 19-year-olds are experiencing such unusually high anxiety.
But while numerous past studies have already linked childhood and adolescent bullying to mental illness, this is the very first study to show that unrelenting victimisation could impact a teenager's mental health by actually reshaping their brain.
The results are cause for worry. During adolescence, a young person's brain is absolutely exploding with growth, expanding at an incredible place.
And even though it's normal for the brain to prune back some of this overabundance, in the brains of those who experienced chronic bullying, the whole pruning process appears to have spiralled out of control.
The teenage years are an extremely important and formative period in a person's life, and these sorts of significant changes do not bode well. The authors suspect that as these children age, they might even begin to experience greater shrinkage in the brain.
But an even longer long-term study will need to be done if we want to verify that hunch. In the meantime, the authors are recommending that every effort be made to limit bullying before it can cause damage to a teenager's brain and their mental health.
This study has been published in Molecular Psychiatry.