Parents’ abusive behaviour can change children’s genes: researchers

It has been long known that domestic violence and child abuse to children, even infants, can lead to permanent alteration of the brain.

Non-genetic family factors, including a history of abuse or neglect during childhood, are risk factors for suicidal behavior: see here, and here. Child abuse and neglect involving children is associated with an increased risk for psychiatric conditions: see here and here and changes in brain development: see here. For a summary, click here.

Now researchers in the United States working with rats have concluded that through a complex process called methylation of the brain, those who are abused or severly stressed as infants can not only have their brains altered by the abuse and stress, but pass on the damaged genes to their offspring.

The research, published in Biological Psychiatry, led by Tania Roth, used 14 rat pups for their first experiment. Half were exposed to a stressed, abusive mother for 30 minutes daily during the first postnatal week, and the other half to a positive caregiving mother during the first postnatal week. The first group was roughly handled or actively rejected by their mothers, whereas the second group was licked, nursed, carried around, or otherwise positively handled.

After the rat pups became adults, the researchers conducted postmortem examinations to see whether there were any differences between the brains of the maltreated rats and the brains of the control rats as far as the expression of a brain-derived gene was concerned. This gene makes a protein that stimulates nerve development in the brain, and it seems to be involved in a number of mental illnesses.

The researchers found changes in the methylation of the gene and in turn changes in the gene expression in the brain of the maltreated animals but not in the control animals.

The researchers then focused on five of the female rats that had been maltreated as infants and looked to see whether they maltreated their own offspring. They did. The researchers also discovered that these offspring had the same gene methylation in the brain that their mothers had had. The alteration of the offspring’s behaviour to that of abusers may have been both genetic and learned behaviours.

“Our results highlight a molecular mechanism that helps explain the far-reaching effects of child abuse and neglect on brain function and behavior,” Roth told Psychiatric News. “This offers a possible explanation for why adolescents and adults who were maltreated as children have higher rates of behavioral problems, substance abuse, and mental illnesses. Furthermore, [the results] give us a framework to help explain why children who have experienced abuse often become abusers themselves.”