Imagine if we could discover which children are most at risk of developing debilitating mental disorders—and even detect these illnesses before the appearance of a single symptom. Think how that knowledge could help parents, schools, nonprofits, and health services organizations design more appropriate, targeted interventions. Well, thanks to recent research breakthroughs in the field of epigenetics (external modifications to DNA that switch genes “on” and “off”), we are one step closer being able to do this.

Michael Meaney, professor of medicine in McGill University’s Douglas Mental Health Institute and the 2014 $1M Klaus J. Jacobs Research Prize recipient, is the driving force behind this research. His work is based on the knowledge that childhood adversity such as poverty or abuse—and even adversity experienced by a child’s ancestors—can affect how cells read genes, preventing children from developing healthy responses to stress and leaving them vulnerable to mental illnesses. These biological effects, Meaney has found, leave behind chemical markers that scientists can measure using a simple swab to collect saliva and a few cells from inside a person’s cheek.

Importantly, not all children who face adversity have the marker, says Anne Petersen, a behavioral scientist and research professor at the University of Michigan. So some children exposed to adversity are more vulnerable than others.

Discovering those who are most at risk is critical, argues Meaney. “We need to treat individual children and not conditions,” he says. “The point is to try to discern vulnerability at the level of the individual child and not to simply rely on the global conditions that predict increased risk.”

The Social Investment Perspective

While it rarely makes headlines, mental illness affects millions of children and adolescents. In fact, globally about 20 percent of young people have mental disorders, according to the World Health Organization, with about half appearing before the age of 14. Mental illness can derail children at a critical stage in their lives, preventing them from becoming healthy, engaged members of society, and potentially placing great emotional and financial burdens on their families.

“It’s extremely important from a social investment perspective to get this right,” says Petersen. “It’s so costly to have these damaged children who go on to become damaged adults.”

A New World of Treatment

Pioneering health practitioners have made great strides in developing increasingly effective programs to target the effects of youth poverty and other specific types of adversity. But these may not be effective for all vulnerable children at all ages. For families, health practitioners, and others, the application of science to the problem of childhood mental illness opens up a new world of treatment. In the same way that scientists are developing customized treatments for cancer, epigenetics will allow them to create tailored interventions for individuals or specific groups.

“Grounded in science, we can develop new ideas and take those to practitioners who are facing problems with children for whom current interventions aren’t working,” says Jack Shonkoff, professor of child health and development at Harvard University’s Center on the Developing Child. Shonkoff’s Frontiers of Innovation initiative is working to understand the consequences of early trauma and determine what prompts changes in a child’s development. “The science can help us be more precise about why we’re doing the things we’re doing,” he says.

Interventions like the Nurse-Family Partnership home visitation program will also benefit from epigenetic advances. Founded on the work of David Olds—professor of pediatrics, psychiatry, and preventive medicine at the University of Colorado and one of Meaney’s partners—the organization helps low-income, first-time mothers cope better with pregnancy, and provides them with training and support focused on their child’s health and development that continues until the child is two years old.

“Let’s say you find individuals who have particular configuration of genetic vulnerability and you know that certain types of experiences are likely to lead to compromised development,” says Olds. “Then you might focus on that segment of the population.”

Shonkoff cites maternal depression as an example of how, in the future, traditional interventions could look radically different. When a mother is depressed, she may be consistently unresponsive to her child, something that can eventually affect the child’s behavior and emotional state. And today, since behavioral research tells us it’s the mother’s depression affecting the child’s behavior, a standard intervention might be to treat her depression.

“But a deeper dive into science could tease out which children are most sensitive to a mother’s poor responsiveness,” says Shonkoff. “That would allow us to develop different treatments for children based on their genetic predispositions to adversity and their individual levels of resilience.”

Meaney stresses that biological testing needs to be seen as part of a range of vulnerability measures. “It doesn’t have to be uniquely at the biological level,” he says. “But it has to be at the level of the individual. And what I can contribute is the biology—that’s my piece of the puzzle.”

As with any closely targeted interventions, ethical questions will emerge. “When you reduce this to the biological level, you would want to make sure that potential risks for stigmatization are thought through very carefully,” says Olds. “This is a general issue for all of us to think about.”

However, better knowledge will pave the way for more effective solutions. Knowing when their children are at risk will empower parents to act. And if biological tests can highlight vulnerability, they could also confirm when certain parenting techniques are successfully strengthening a child’s mental resilience. Meanwhile, for health practitioners, epigenetic insights could help reduce unnecessary pharmacological treatments.

Perhaps most importantly, knowing which children are most at risk will allow us to focus limited resources where they matters most. Doing so means making more progress in the battle to prevent children from developing debilitating life-long mental conditions. And, ultimately, we will increase the pool of individuals who go on to lead healthier, more productive lives.