Chronic aggressive behavior exhibited by some boys may be due to epigenetic changes during pregnancy and early childhood, according to two studies published in the journal PLOS ONE.
In the first study, the researchers found that among men who had chronic aggressive behavior during childhood and adolescence, blood levels of four biomarkers of inflammation were lower than in men who exhibited average levels of aggressive behavior in their youth. "Using four specific biomarkers of inflammation, called cytokines, we were able to distinguish men with chronic physical aggression histories from those without," explained Richard E. Tremblay, from the University of Montreal.
In the second study, it was observed in the same men that the DNA encoding the cytokines showed altered methylation patterns. "Methylation is an epigenetic modification - hence reversible - of DNA, in relation to parental imprinting. It plays a role in regulating gene expression", noted McGill University's Moshe Szyf, lead researcher on the second study.
Szyf adds that the pre- and postnatal environment could cause these differences in biomarkers associated with chronic aggression. 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 behavior.
Tremblay says that previous studies have suggested that men with aggressive pasts have one thing in common: the characteristics of their mothers. "They are usually young mothers at the birth of their first child, with low education, often suffering from mental health problems, and with substance abuse problems," he explained. "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."
Both Tremblay and Szyf are optimistic that their work could lead to effective early interventions. "If our results show that behavioral problems originate from as far back as pregnancy, it means that we can reduce violence through preventive intervention from as early as pregnancy," says Tremblay. "We have already shown that support given to families of aggressive boys in kindergarten prevents school dropout and crime in adulthood."
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Source: University of Montreal