Childhood maltreatment and adversity have been shown to affect cortisol reactivity and stress responses. That means people who have experienced negative life events in childhood, such as childhood sexual abuse or neglect, are likely to have disrupted stress responses and reactivity. Moreover, children with a history of maltreatment are more likely to exhibit internalizing or externalizing problems than those with no history of maltreatment.
But are people genetically predisposed to victimization? Isabelle Ouellet-Morin, PhD, of the Social, Genetic, and Developmental Psychiatry Centre at the Institute of Psychiatry at King’s College London, wanted to explore whether some people are genetically predisposed to stress reactivity via a unique serotonin transporter gene (SERT) promoter that affects cortisol response. Using a sample of 28 pairs of twin children, Ouellet-Morin evaluated their SERT DNA and assessed how it differed between one person in the twin set who was bullied, and the other, who had not been bullied.
She found that the children who were bullied at age 10 had higher levels of SERT DNA changes that reduced cortisol responses. When she looked at these same levels prior to victimization, she found that these levels increased more in the twins who would later be bullied when compared to those who did not report subsequent bullying. This suggests that the bullied children may have had a genetic predisposition to stress reactivity that could have made them more vulnerable to bullying.
Existing research on SERT DNA and cortisol responses shows that similar patterns are evident in adults with a history of abuse and that this hormonal process is associated with antisocial behavior, posttraumatic stress, and depression. Ouellet-Morin believes that these results support the existing data on SERT DNA, and demonstrate that even in early childhood, prior to reported victimization, genetic risk factors may exist in some people.
She added, “This epigenetic mechanism may serve as an interface between childhood victimization, later vulnerability to stress and psychopathology.” Although these results are significant, the sample sized used in this study is small and future work should examine larger samples and explore other factors that could influence these outcomes.
Ouellet-Morin, I., et al. (2013). Increased serotonin transporter gene (SERT) DNA methylation is associated with bullying victimization and blunted cortisol response to stress in childhood: A longitudinal study of discordant monozygotic twins. Psychological Medicine 43.9 (2013): 1813-23. ProQuest. Web.
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