Chronic aggressive behaviour exhibited by some boys from disadvantaged families may be due to epigenetic changes during pregnancy and early childhood. This is highlighted by two studies conducted by a team led by Richard E. Tremblay, professor emeritus at the University of Montreal and Moshe Szyf, professor at McGill University, published in the journal PLOS ONE. The first author of the two papers, Nadine Provenal, was jointly supervised by professors Szyf and Tremblay.
Epigenetic changes possibly related to the prenatal environment
In the first study, published in July, the team found that among men who had chronic aggressive behaviour during childhood and adolescence, blood levels of four biomarkers of inflammation were lower than in men who exhibited average levels of aggressive behaviour in their youth, from 6 to 15 years of age. "This means that using four specific biomarkers of inflammation, called cytokines, we were able to distinguish men with chronic physical aggression histories from those without," says Tremblay, a researcher specializing in developmental psychology. In the second study, it was observed in the same men with aggressive pasts, that the DNA encoding the cytokines showed methylation patterns different from those of the comparison group.
"Methylation is an epigenetic modificationhence reversibleof DNA, in relation to parental imprinting. It plays a role in regulating gene expression", says Szyf, who specializes in epigenetics.
The pre- and postnatal environment could cause these differences in biomarkers associated with chronic aggression," Szyf added. Various studies conducted with animals show that hostile environments during pregnancy and early childhood have an impact on gene methylation and gene programming leading to problems with brain development, particularly in regard to the control of aggressive behaviour.
Previous work by Tremblay's team suggest that men with aggressiv
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University of Montreal