The finding was published in the journal Psychological Medicine and came from Isabelle Ouellet-Morin, a scientist at the Centre for Studies on Human Stress (CSHS) at the Hôpital Louis-H. Lafontaine and professor at the Université de Montréal.
Bullying is a serious problem that can affect all people, not just children. A recent study from BMJ showed that adult victims of bullying at work, or even just witnesses of bullying, are more likely to be prescribed antidepressants, tranquilizers or sleeping pills.
Previous research has also observed the long-term effects of bullying, such as behavioral problems, alcohol use, smoking, eating disorders, and mental health issues.
The current study was set out to closely examine the mechanisms that explain how people's responses to stressful situations become altered due to tough events they experienced.
"Many people think that our genes are immutable; however this study suggests that environment, even the social environment, can affect their functioning. This is particularly the case for victimization experiences in childhood, which change not only our stress response but also the functioning of genes involved in mood regulation."
Prior research, conducted by the same author at the Institute of Psychiatry in London (UK), demonstrated that kids who are bullied produce less of the stress hormone, cortisol. However, they behaved more aggressively and had trouble interacting with others.
Ouellet-Morin's current research shows that when a victim is 10 years old, the structure surrounding a gene called SERT, responsible for controlling serotonin - a neurotransmitter which plays a part in adjusting mood and depression, may be the reason why the child experiences a decrease of cortisol at about age 12.
The researcher made this discovery after evaluating 28 pairs of identical twins who were 10 years old on average. One twin was a victim of bullying at school and the other twin was not bullied by peers.
"Since they were identical twins living in the same conditions, changes in the chemical structure surrounding the gene cannot be explained by genetics or family environment. Our results suggest that victimization experiences are the source of these changes."
The author suggests that experts should now look into the possibility of helping bullied kids change the psychological impact, potentially through interventions at school and by providing comfort and support to victims.
Written by Sarah Glynn