Researchers at the University of Wisconsin-Madison and Georgia State University have uncovered the neurological impact of early childhood stress on the human brain. From these results, it may be possible to determine why some individuals who are exposed to these stressors later go on to develop mental health problems.
This study was published in the scientific journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.
Scientists and clinicians have long recognized that early childhood stress can increase the risk of a person later developing mental illness. Many children who experience these same stressors, however, go on to live happy and healthy lives. Why?
Marilyn J. Essex, Ph.D., a professor of psychiatry at the University of Wisconsin, sought to determine how the brain adapts to childhood adversity and whether or not this ability to adapt differed between healthy children and children who would ultimately develop mental illness.
Dr. Essex and colleagues followed 132 children from infancy until late adolescence (age 18) and measured whether or not they experienced one of the more common forms of childhood adversity (e.g., negative parenting, parental conflict or financial stress) before the age of 12.
Once the participants reached adolescence, the researchers examined their behavior for symptoms of anxiety and depression. Children who had experienced childhood adversity but DID NOT demonstrate symptoms of depression or anxiety were considered to have emotionally adapted to their situation.
The researchers then used neuroimaging (specifically functional magnetic resonance imaging, or fMRI) to determine how childhood adversity — and the emotional adaptation to that adversity — influenced the brain.
When the researchers showed participants images designed to evoke negative emotions, children who had experienced childhood adversity demonstrated greater-than-usual activity in the amygdala, a brain region involved in emotional processing.
“Childhood adversity may sensitize the amygdala to negative emotional content, but this appears to be a normative, adaptive response that could allow better detection of threat for kids growing up in stressful environments,” explained Ryan J. Herringa, M.D., Ph.D., the first author of the study and an assistant professor of child and adolescent psychiatry at the University of Wisconsin-Madison.
The researchers also looked at functional connectivity, or how frequently two or more brain regions are active at the same time. Although functional connectivity does not measure the physical connection between two brain regions, it can help researchers identify neural networks that may be working together.
Individuals who had experienced early childhood adversity demonstrated a stronger functional connection between the amygdala and prefrontal cortex, a neural circuit that has been previously associated with emotional regulation. Adolescents who had difficulties adjusting to childhood adversity, however, had a much weaker connection between these two brain regions.
“These findings point to a neural circuit that may be involved in emotional resilience and could be used as a potential treatment target for individuals suffering from anxiety and depression in the wake of adversity,” said Dr. Herringa.
What does this mean?
From these results, it seems as though childhood adversity can influence activity within the amygdala, one of the brain regions engaged in emotional processing. It also seems as though individuals who later go on to develop symptoms of depression and anxiety have a weaker functional connection between the amygdala and the prefrontal cortex, a neural circuit that helps regulate emotions. This weaker connection may be why these children later go on to develop mental illness.
“The study shows us how experience changes the brain and how resilience reflects healthy emotion regulation,” explained Cameron S. Carter, M.D., editor of Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.
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About the author
Courtney Lopresti, M.S., is a senior staff writer, where she uses her scientific background to write online blogs and articles for a general audience. At the University of Pittsburgh, where she earned her master’s in neuroscience, she used functional neuroimaging to study how the human cerebellum contributes to language processing. In her spare time, she writes fiction, reads Oliver Sacks and spends time with her two cats and bird. Courtney is currently located in Minneapolis.