At a young age, children depend on their caregivers for love and support. Those who have that love and support replaced with abuse and neglect, however, grow up in fear, unsure of who they can trust. Some aspects of life become particularly difficult for them, and their risk of partaking in harmful behaviors increases. According to a new study published in the journal Child Development, the increased risk of these behaviors, such as aggression and alcohol abuse, may stem from the biological processes the body goes through after abuse, especially among the genes.

Researchers from the University of Wisconsin, Madison, recently discovered that children who had been abused or neglected showed signs of a biochemical process called methylation in certain genes. Scientifically, methylation is the addition of a methyl group (CH3) to a molecule. When that molecule is DNA, methylation occurs, and subsequently controls whether certain genes are activated or become inactive.

For the kids who were neglected or abused, methylation occurred in parts of the gene known as the glucocorticoid receptor gene, or NR3C1, which is responsible for the brain’s response to stress, as well as other immune functions. Specifically, it affected the way their brains secreted a protein called nerve growth factor, which is critical for healthy brain development. “This link between early life stress and changes in genes may uncover how early childhood experiences get under the skin and confer lifelong risk,” said Seth Pollak, a professor of psychology and pediatrics at the university, in a press release.

Scientists have long hypothesized that the effects of abuse and neglect on children were severe enough to cause a chemical breaking point in their bodies, which manifests through abnormal behavior and psychological disorders. A study from last year found that middle-aged African-Americans who experienced abuse as children and had gone on to develop post-traumatic stress disorder also exhibited methylation in stress-related genes. According to the National Child Abuse Hotline, more than three million reports of abuse are made every year involving over six million kids. Many kids who are abused go on to develop mood disorders and other psychiatric conditions, while also being more prone to criminal and risky sexual behavior.

For the current study, the researchers analyzed blood samples of 56 children aged 11 to 14, of whom half had been abused at some point in their life. All of the children who had been abused showed excess methylation in the NR3C1 genes. Disruptions in this gene have been associated with difficulty handling emotions and stress, as well as problems with the immune system, causing a higher likeliness of falling ill.

“Our finding that children who were physically maltreated display a specific change to the glucocorticoid receptor gene could explain why abused children have more emotional difficulties as they age,” Pollak said. “They may have fewer glucocorticoid receptors in their brains, which would impair the brain’s stress-response system and result in problems regulating stress.”

The researchers said that the findings could help with developing interventions for children, which would be aimed at improving caregiving and reversing methylation. Based on a study out just this week, these interventions would be helpful. The study found that a parent-child intervention, which taught better parenting and communication skills, among other things, was effective at reducing inflammation in kids. If they can improve the kids’ immune responses, it should be safe to assume they can improve mental health, too.

Source: Pollak SD, Romens SE, McDonald J, Svaren J. Associations Between Early Life Stress and Gene Methylation in Children. Child Development. 2014.