This fact 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. The first author of the two papers, Nadine Provencal, was jointly supervised by professors Szyf and Tremblay.
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.
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.
Szyf, who specializes in epigenetics, said that methylation is an epigenetic modification-hence reversible-of DNA, in relation to parental imprinting. It plays a role in regulating gene expression.
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 aggressive pasts have one thing in common: the characteristics of their mothers.
The significant difficulties these mothers experienced during pregnancy and the early childhood of their child may have an impact on the expression of genes related to brain development, the immune system, and many other biological systems critical for the development of their child.
The study has been published in the journal PLOS ONE.