DUKE (US)/KING’S COLLEGE LONDON (UK)—A genetic variation may moderate whether victims of bullying will go on to develop emotional problems, a new study finds.

A growing body of evidence from studies of gene and environment interactions demonstrates that children who are victims of bullying are at risk for developing emotional problems—including depression. However, not all children who are bullied go on to develop such problems.

A team of researchers from Duke University and King’s College London tried to assess whether a genetic variant could contribute to emotional disturbance in children who are bullied. Their findings appear in the Journal of the American Academy of Child and Adolescent Psychiatry (JAACAP).

They looked at a sample of 2,232 same-sex twins. Assessments were conducted in 1999-2000 when the children were 5 years old, and follow-up assessments were made at age 12.

The children were evaluated for emotional problems reported by their mothers and teachers using the Child Behavior Checklist and the Teacher’s Report Form. In addition to interviews, DNA samples acquired via cheek swabs were evaluated to determine the presence or absence of variation in the 5-HTTLPR gene.

The researchers observed that genetic differences, specifically the SS genotype, seem to interact with bullying victimization to exacerbate emotional problems.

They also found that the strength of this genetically influenced response is related to the frequency of the bullying experience (i.e., the gene and environment interaction was strongest for frequently bullied children).

“This genetic moderation persists after controlling for children’s pre-victimization emotional problems and for other risk factors shared by children growing up within the same family environment,” the authors write.

The present findings are consistent with a 2009 study that found that adolescent girls with the SS genotype who were victims of relational aggression are more prone to depression.

The current study is one of several articles to be published in the August and September issues of JAACAP that explore the intersection of genetics and mental health disorders in children and adolescents.

“These (study) designs have moved us well beyond the fiery but misguided debates about nature versus nurture,” according to an accompanying editorial in JAACAP by James Hudziak and Stephen Faraone. “We have learned that both domains affect psychopathology, exerting effects that sometimes act independently of one another and sometimes interactively, as when risk DNA variants make some children more susceptible to the onset of illness.

“Twin studies show that gene action can be complex, with DNA variants at a gene locus sometimes acting additively (in a dose-response manner) and sometimes with classic dominant or recessive modes of inheritance.”

“Candidate gene studies such as these could lead to public health interventions (e.g. greater efforts to decrease bullying) that may lower the prevalence of child psychopathology,” Hudziak and Faraone wrote.

This study was supported by the UK Medical Research Council and U.S. National Institutes of Health.

More news from Duke: www.duke.edu/today/
More news from King’s College London: www.kcl.ac.uk/news