Childhood stressors such as physical and sexual abuse, emotional and physical neglect, and as they grew older, bullying, cyber-victimization, and crime caused limited evidence of long-term epigenetic changes, according to a recent study published in the American Journal of Psychiatry.
Whole blood samples from sets of twins (n=1658) in the Environmental Risk Longitudinal Study in England were assessed for DNA methylation in response to childhood victimization at ages 5, 7, 10, 12, and 18 years of age. The sample socioeconomic parameters closely matched those of England as a whole.
Among adolescents, which is considered the peak age period for victimization, victimization represented <1% difference in DNA methylation, and no clinically significant changes were detected based on type of victimization. However, smoking in adolescents, which is known to affect DNA methylation, was significantly higher among those who were victimized.
Childhood victimization has been hypothesized to be especially potent, and the findings from this study showed childhood sexual victimization is associated with stable DNA methylation differences in whole blood. However, a low sample size and lack of methylation in adolescent samples highlight the need for caution in interpretation.
Overall, there is limited evidence that victimization leads to DNA methylation in peripheral blood, and the effects of victimization are outweighed by those of environmental stressors such as smoking.
The study authors wrote, “Observational studies using free-ranging humans, relying on peripheral tissue, and using currently available high-throughput technologies appear to yield weak and inconsistent evidence on the epigenetics of early-life stress.” They added, “We need to come to terms with the possibility that epigenetic epidemiology is not yet well matched to nonhuman experimental models in uncovering how stress gets under the skin in humans”.
Marzi SJ, Sugden K, Arseneault L, et al. Analysis of DNA methylation in young people: limited evidence for an association between victimization stress and epigenetic variation in blood [published online January 12, 2018]. Am J Psychiatry. doi:10.1176/appi.ajp.2017.17060693