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Trauma-related disorders are some of the most common mental health conditions in the United States. Trauma includes any event that creates an actual or perceived threat to a person’s life, as well as experiencing or witnessing emotional, physical, or sexual abuse. What happens in our environment can change the way our bodies and brains develop and respond to situations in the future. Clinically, trauma-related symptoms are measured through one-to-one interviews and surveys. These interviews can be helpful in determining the patient’s perception of their traumatic experience and their subjective feelings associated with the situation. However, these subjective self-report methods may not fully capture the severity and impact of the trauma on a person due to factors such as stigma, memory bias, or the survivor’s inability to explain their traumatic experiences. Our lab is interested in combining these subjective reports of trauma with objective measures, such as physiological processes, to better capture the full impact of trauma on the brain and body. In this case, we studied traumatic experiences in children whose brains are developing rapidly and for whom trauma may have long lasting neural and psychological effects.
To measure how trauma might affect our body’s response, we had two types of physiological measures: skin conductance and resting heart rate. Skin conductance measures the level of sweating on your palms, and heart rate measures the number of times your heart beats in a minute. We found some very interesting results with both measures and were able to publish them in peer-reviewed scientific journals.
Below is a summary of our results:
Skin conductance response predicts vulnerability for future post-traumatic stress disorder (PTSD) symptoms
Link to full article: HERE
We used an app called eSense to capture skin conductance response on an iPad while our participants were recalling their traumatic experiences. Participants were asked about their experience of community violence, personal injuries, natural disasters, verbal and sexual abuse. If the participant said yes to any of these traumatic experiences, then they would be asked to provide further details of the event. An example of how we measured skin conductance is shown in the picture below.
Our results showed that talking about their traumatic experiences increased how much children’s hands were sweating. This suggests that skin conductance can be a biomarker for measuring the “fight or flight” system of the body that is responsible for involuntary stress reactions following trauma. Importantly, the size of this reaction was related to how many PTSD symptoms the children had two years later. This predictive association was true only for children who did not have high levels of traumatic exposures, possibly because the children with severe trauma were more likely to have future PTSD regardless of how their body responded to the questions. But many children with low to moderate exposure were resilient, and only those who showed this increased sweat response might have been more vulnerable. These findings might point us to biological factors that are related to increased risk, i.e. biomarkers. These results can also be viewed in the more descriptive infographic below.
Resting heart rate variability is associated with increased PTSD severity for girls, but not boys, in trauma-exposed children
Link to full article: HERE
Alongside skin conductance, we wanted to also look at the association between heart rate and PTSD symptoms. Heart rate is another measure of the “fight or flight” system that may be altered following exposure to prolonged stress. We measured children’s heart rate while they were resting in a comfortable position and later asked questions to measure their PTSD severity. In this study, we found that 9-year-old girls with lower resting heart rate had higher PTSD symptoms. We did not find this same association in boys. Lower heart rate is more like what we see in adults, so one possible explanation is that the girls with more PTSD symptoms showed faster aging in how their hearts beat. This might put them at greater risk for heart disease in the future. However, if we are able to see these changes early in life, we might be able to prevent some of these negative health consequences later.
Summary: When looking at how trauma impacts the biology of the brain and body, there are many variables that we need to consider. Both of the examples above show that there is no clear-cut association between biomarkers and PTSD severity. Other factors such as the severity of trauma exposure and biological sex add complexity to how PTSD develops in children. Our findings show that greater skin conductance is associated with higher PTSD symptoms in children with less severe trauma and that lower heart rate may be associated with earlier aging specifically in girls. Future studies should take into account other variables such as parenting behavior, other environmental factors, and brain connectivity to better understand how trauma leads to risk for PTSD and other stress-related disorders.
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