Childhood Adversity Stalls Brain Region’s Growth, Raises Psychosis Odds

In a new study, a University of Texas at Dallas researcher has shown that adverse childhood experiences and their associated stress are linked to reduced development of a crucial region of the brain and increase the risk for psychotic-like experiences (PLE) during the transition from childhood to adolescence.

Dr. Katherine Damme, assistant professor of psychology in the School of Behavioral and Brain Sciences, is corresponding author of the study published in the November print edition of Psychoneuroendocrinology.

"This paper shows how early-life stress drives the reduction in size of the hippocampus in 8- to 11-year-olds and links those factors to the frequency and severity of psychotic-like experiences," she said.

Stress has been linked to increased vulnerability to psychosis in adults, but the mechanisms behind that link are poorly understood. Similarly, reduced hippocampal volume in adults has previously been tied to both psychosis risk and early-life stress.

"The novelty of our research is that it suggests that childhood neurodevelopment impaired by stress could be an early risk factor for future psychosis," Damme said.

Adverse childhood experiences (ACE) are defined by the Centers for Disease Control and Prevention (CDC) as potentially traumatic events that adversely affect health and well-being. The CDC categorizes these into 10 groups (see box).

Damme and her colleagues used a dataset from the Adolescent Brain Cognitive Development Study, the largest long-term study of brain development and child health in the U.S. that includes data collected from more than 11,000 demographically diverse children at 21 U.S. sites. They were assessed for ACE exposure, hippocampal volume and PLE severity.

"We've taken this data-driven, objective measure and applied it to the conversation about stress and early psychosis," she said. "These findings are consistent with a hippocampal vulnerability model of psychosis risk."

In their analysis, the researchers found that the relationship between the severity of psychotic-like experiences and hippocampal volume varied depending on the level of adverse events in childhood.

"Individuals with high PLE severity and high ACE exposure showed significantly lower hippocampal volume compared to peers with no ACE exposure or low PLE severity," Damme said. "Unexpectedly, we also found that individuals with high PLE severity and no ACE exposure showed an increase in hippocampal volume compared to peers with lower PLE severity."

While researchers concluded that high stress levels were demonstrably connected to hippocampus vulnerability, they also concede there might be other undetected factors at play.

"There may be a genetic vulnerability for psychosis at work, interacting with stress levels - but the study didn't produce evidence of that," Damme said. "There are many pathways that increase the risk of psychosis. This highlights one unique pathway: adverse childhood events, smaller hippocampus and high stress levels."

"There are many pathways that increase the risk of psychosis. This highlights one unique pathway: adverse childhood events, smaller hippocampus and high stress levels."

Dr. Katherine Damme, assistant professor of psychology in the School of Behavioral and Brain Sciences

Damme said that while there are no clear interventions to mitigate the risk of children developing psychotic-like experiences, nurturing hippocampus growth could be beneficial.

"What can be done to counteract this is to positively impact hippocampal volume via high levels of physical activity and good sleep hygiene," she said. "However, the circumstances of many children make exercise and sleep interventions impractical due to environmental factors, with outsized effects on those with lower socioeconomic status - air pollution, lack of space for exercise, difficult sleeping environments and more.

"With other interventions, like giving children antipsychotics, there can be many side effects in a lot of systems. Engaging in regular, moderate physical activity and having better sleep hygiene are very unlikely to do anyone harm."

Additional contributors from Northwestern University, where Damme began this research as a postdoctoral fellow before joining UTD this year, are senior author Dr. Vijay Mittal, department chair of psychology, and clinical psychology doctoral student Ivanka Ristanovic. Damme's research is supported by grant R21MH136408 from the National Institute of Mental Health (NIMH), a component of the National Institutes of Health. Mittal is supported by four additional NIMH grants.

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