Research has shown that approximately two-thirds of the population have experienced some form of childhood adversity by the age of 18. So why do so many people emerge from difficult childhoods seemingly unscathed, while others develop various forms of mental illness? And are there any evident brain differences between the two types?
Researchers at the University of Wisconsin may have discovered some of the answers to these questions. In a new study, they found a thicker connection between the amygdala and the prefrontal cortex in people who had experienced an adverse childhood but had never developed any symptoms of depression or anxiety. However, in people with similar childhoods who later developed depression and/or anxiety, this connection was notably weaker.
The findings could help explain how the brain adapts to childhood adversity and may also predict which kids may be vulnerable to developing later psychopathology.
For the study, senior author Dr. Marilyn Essex, Professor of Psychiatry at the University of Wisconsin, and colleagues followed 132 kids from infancy to 18 years old to search for a neurobiological mechanism of emotional adaptation.
The researchers focused on common types of childhood adversity, such as negative parenting, parental conflict, and financial stress that occurred between infancy and 11 years of age. When the subjects were 15 to 18 years old, the researchers studied their behavior to look for symptoms of anxiety and depression — they defined emotional adaptation as an absence of these symptoms.
Using functional magnetic resonance imaging, the researchers also studied the subjects’ brain responses during emotional processing in order to observe any associations between brain activity, childhood adversity, and emotional adaption.
They found that when the teens viewed images that evoked negative emotions, those who experienced childhood adversity had a more reactive amygdala, a region of the brain involved in emotion 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,” said first author of the study Dr. Ryan Herringa, Assistant Professor of Child and Adolescent Psychiatry at the University of Wisconsin-Madison.
The researchers also found that childhood adversity was associated with a stronger connection between the amygdala and the prefrontal cortex, an important circuit for regulating emotion, but this was reduced in adolescents with high anxiety and depressive symptoms.
Herringa explained this could mean that the ability of the brain to strengthen the connection between the amygdala and prefrontal cortex strengthens emotional adaptation.
“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,” Herringa said.
The findings are published in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.