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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Psychiatry | doi: 10.3389/fpsyt.2019.00696

Frequent bullying involvement and brain morphology in children

 Ryan L. Muetzel1*,  Rosa H. Mulder1, 2,  Sander Lamballais3, Andrea P. Cortes1, Pauline Jansen4,  Berna Güroğlu5,  Meike Vernooij6,  Manon H. Hillegers1, Tonya White1,  Hanan El Marroun1, 7 and Henning Tiemeier8
  • 1Department of Child and Adolescent Psychiatry/Psychology, Erasmus Medical Center, Netherlands
  • 2Department of Family Social Sciences, Leiden University, Netherlands
  • 3Department of Epidemiology, Erasmus Medical Center, Netherlands
  • 4Department of Psychology, Education and Child Studies, Erasmus University Rotterdam, Netherlands
  • 5Institute of Psychology, Leiden University, Netherlands
  • 6Department of Radiology, Erasmus Medical Center, Netherlands
  • 7Erasmus University Rotterdam, Netherlands
  • 8School of Public Health, Harvard University, United States

Background
Over the past few decades, bullying has been recognized as a considerable public health concern. Involvement in bullying is associated with poor long-term social and psychiatric outcomes for both perpetrators and targets of bullying. Despite this concerning prognosis, few studies have investigated possible neurobiological correlates of bullying involvement that may explain the long-term impact of bullying. Cortical thickness is ideally suited for examining deviations in typical brain development, as it has been shown to detect subtle differences in children with psychopathology. We tested associations between bullying involvement and cortical thickness using a large, population-based cohort.
Methods
The study sample consisted of 2,602 participants from the Generation R Study. When children were 8 years old, parents and teachers reported on common forms of child bullying involvement (physical, verbal, and relational). Questions ascertained whether a child was involved as a perpetrator (n=82), a target of bullying (n=92), as a combined perpetrator and target of bullying (n=47) or uninvolved in frequent bullying (n=2,381). High-resolution structural magnetic resonance imaging was conducted when children were 10 years of age. Cortical thickness estimates across the cortical mantle were compared amongst groups.
Results
Children classified as frequent targets of bullying showed thicker cortex in the fusiform gyrus compared to those uninvolved in bullying (B = 0.108, pcorrected < 0.001). Results remained consistent when adjusted for socioeconomic factors, general intelligence, and psychiatric symptoms. Children classified as frequent perpetrators showed thinner cortex in the cuneus region, however this association did not survive stringent correction for multiple testing. Lastly, no differences in cortical thickness were observed in perpetrator-targets.
Discussion
Bullying involvement in young children was associated with differential cortical morphology. Specifically, the fusiform gyrus, often involved in facial processing, showed thicker cortex in targets of frequent bullying. Longitudinal data are necessary to demonstrate the temporality of the underlying neurobiology associated with bullying involvement.

Keywords: cortical thickness, Victimization, Vertex-wise analysis, population-based, fusiform

Received: 13 Apr 2019; Accepted: 28 Aug 2019.

Copyright: © 2019 Muetzel, Mulder, Lamballais, Cortes, Jansen, Güroğlu, Vernooij, Hillegers, White, El Marroun and Tiemeier. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Ryan L. Muetzel, Erasmus Medical Center, Department of Child and Adolescent Psychiatry/Psychology, Rotterdam, Netherlands, r.muetzel@erasmusmc.nl