Trauma suffered in childhood echoes across generations, study finds

Trauma in childhood echoes through generations, according to new research that could have implications for thousands of migrant children recently separated from parents at the U.S. border.

The study, conducted by researchers at the University of California at Los Angeles and published today in Pediatrics, finds that traumatic events in childhood increase the risk of mental health and behavioral problems not just for that person but also for their children.

“Early-life experiences -- stressful or traumatic ones in particular -- have intergenerational consequences for child behavior and mental health," the lead author, Adam Schickedanz, clinical instructor in pediatrics at the David Geffen School of Medicine at UCLA, told ABC News. "This demonstrates one way in which all of us carry our histories with us, which our study shows has implications for our parenting and our children's health.”

Asked by ABC News how the research may relate to the more than 2,000 children recently separated from their families after crossing the U.S. border, Schickedanz said all families who participated in the study were from the U.S. but that evidence suggests the effects of adverse childhood events "take a toll in large part as a result of toxic stress responses that appear to be universal, since they have been demonstrated across families from diverse backgrounds."

The researchers looked at the effects over a generation when a child grows up in an unstable environment, suffers neglect or has absent parents. "Based on the available evidence, one would expect that the stresses and trauma children are experiencing due to family separation at the border will have intergenerational behavioral health consequences," Schickedanz said.

The study used a national sample of families from previous research -- parents who had participated in a 2014 Child Development Supplement and 2,529 of their children who had complete data in the 2014 Childhood Retrospective Circumstances Study.

The severity of a child's behavioral issues was measured through a scale called the behavior problems index. Researchers gave the primary caregivers of children ages 3 to 17 years old a series of questions to assess present problems, including with anxiety, depression, dependency, hyperactivity, and aggression.

The study found a link between children with a high rate of behavioral problems and parents who had experienced a greater number of adverse childhood events, ACEs.

Parents who growing up suffered four or more adverse events before they were 18 -- including neglect, abuse and household dysfunction -- were more likely to have children with behavioral issues, such as being hyperactive or having problems regulating their emotions, the research found.

Among the group studied, one-fifth of the parents had four or more traumatic experiences as children.

The researchers also found that a parent's gender was a factor in the outcome of the child. Children's outcomes were more negatively affected when it was their mothers, rather than fathers, who suffered trauma as children. Researchers explained this by noting that mothers are more often the primary caregivers.

This is the first study showing a correlation between adverse events in childhood and outcomes for the children of those who suffered the original trauma, and the researchers don’t want to stop there.

“Right now, we are exploring whether these intergenerational [adverse event] associations persist across more than one generation. In fact our study team's next step is to examine whether grandparents' [adverse childhood events] can be linked to their grandchildren's behavioral health.”

While this study focused on the behavioral consequences of traumatic childhood experiences, other research has shown that adverse childhood events affect physical health, increasing the risk of chronic disease and premature mortality later in life.

Denise Powell, M.D. candidate, is a student from Jackson, Mississippi, working in the ABC News Medical Unit.