Childhood adversity may increase the risk of neurodevelopmental conditions, including ADHD

Experiencing adverse events in childhood, such as parental death or divorce, family violence, or poverty, is associated with an increased risk for common neurodevelopmental conditions, including autism, attention deficit hyperactivity disorder (ADHD), and learning disability, according to a recent University of Iowa study.

The study, led by Lane Strathearn, MD, PhD, professor of pediatrics-developmental and behavioral pediatrics at the UI Carver College of Medicine, adds to evidence that childhood adversity can increase the risk for many chronic physical and mental health problems that last into adulthood and are difficult and costly to treat. But the new study also suggests that multiple Adverse Childhood Events (ACEs) can have a cumulative effect on the risk for developing these conditions.

The new findings, published in the journal Children, raise the possibility that providing resources or support to families dealing with these stressors might help lower the risk for some of these life-long conditions.

“This study suggests that we should focus our attention on prevention, where we can intervene and potentially change the trajectory for these medical conditions,” says Strathearn, who also is co-director of the newly established Hawkeye Intellectual and Developmental Disabilities Research Center (Hawk-IDDRC) and physician director of the Center for Disabilities and Development. “If we understand the connection between these adverse experiences and development, then that helps us to prioritize prevention rather than cure and intervention.”

A spectrum of effect – ACEs, neurodevelopment and behavior

Strathearn and his colleagues tracked seven adverse childhood events (ACEs) known as household challenges: death of a parent, incarceration, divorce or separation, family violence, mental illness, substance abuse, and poverty, and analyzed if they were associated with an increased risk for 15 different neurodevelopmental and behavioral health conditions.

The researchers used data from the 2016–2019 National Survey of Children’s Health, a well-established nationwide, population-based survey, which provides data on 130,000 children from across the United States.

Some of the findings were expected based on previous research on the genetic basis for some conditions. For example, the researchers found that Down Syndrome, which is a genetic condition, was not at all associated with household challenge ACEs.  At the other end of the spectrum, the study found that conduct problems, depression, and substance abuse were very strongly associated with ACEs – the risk of developing these conditions was six to nine times higher among children who experienced ACEs, which matched previous findings.

More surprising was the finding that other neurodevelopmental conditions not traditionally linked with childhood adversity showed moderate yet robust associations with ACEs, including autism, epilepsy, and speech disorder. Even stronger associations were seen for intellectual disability, headaches or migraine, developmental delay, learning disability, anxiety problems and ADHD.

“ADHD, for example, is an extremely common developmental condition that affects millions of children in the United States, and the rates of diagnosis are increasing,” Strathearn says. “This study suggests that early childhood experiences may contribute to these symptoms later in life.”

Moreover, the team found a “dose-response” to the effect; as the number of reported ACEs increased, the risk for having one of these neurodevelopmental disorders also increased.

Supporting families may impact developmental and behavioral issues

Strathearn says that the research really highlights the impact environmental factors can have on neurodevelopment and behavior and suggests that interventions aimed at alleviating some of these stressors might have a significant impact on the outcomes themselves.

“I think we need to focus on a broader, societal impact—on the factors that contribute to the greatest parental stress, such as financial issues, mental health challenges, unemployment,­ as well as providing education to parents so that they can better understand how to respond to their child during those first few years of life,” he says. “I think we should do more to provide education and support for families, working on a community level.”

Strathearn notes that the one of the goals of the Intellectual and Developmental Disabilities Research Center (IDDRC) is to broaden the research base to look at other environmental factors that may contribute to neurodevelopmental conditions, and how these factors may intersect with genetic risk factors.

“Over recent years, there has been a greater awareness of how experiences in childhood can impact development and behavior later in life. But I think we've got a long way to go to fully understand the mechanisms,” he says.

In addition to Strathearn, the UI research team included co-first authors Kasra Zarei, and Guifeng Xu, as well as Bridget Zimmerman and Michele Giannotti.

The study was funded in part by grants from the National Institutes of Health. Zarei was a trainee of the Leadership Education in Neurodevelopmental and Related Disabilities (LEND) program, a national interdisciplinary leadership training program for graduate students. The Iowa LEND program is affiliated with the University of Iowa Stead Family Children’s Hospital and is located within the Center for Disabilities and Development.