Summary: Survivors of the 1995 Oklahoma City bombing continue to carry hidden biological imprints of trauma, even decades after the event and in the absence of visible mental health issues. A new study reveals subtle yet significant changes in stress biomarkers, including cortisol levels, heart rate, blood pressure, and inflammatory interleukins.
While survivors report resilience and low PTSD or depression scores, their physiological responses show heightened alertness and immune system changes. These findings underscore the lasting physical impact of trauma, even when emotional recovery appears complete.
Key Facts:
- Biological Residue of Trauma: Survivors had lower cortisol, higher blood pressure, and altered heart rate—indicating lasting stress system changes.
- Inflammatory Markers: Elevated interleukin 1B and reduced interleukin 2R suggest ongoing immune system imbalance in trauma survivors.
- Disconnect Between Mind and Body: Psychological symptoms did not correlate with the altered biological stress responses.
Source: University of Oklahoma
Recent research from the University of Oklahoma suggests that survivors of the 1995 Oklahoma City bombing carry physiological traces of the trauma, even though study participants have gone on to lead healthy and resilient lives.
Essentially, their bodies “remember” the trauma even if they don’t have physical or mental health problems.
Previous studies have examined biological stress and psychological symptoms in terrorism survivors, but the recently published research is thought to be the first of its kind to study three different biological systems in medically healthy people who survived the same traumatic event: cortisol, which plays a crucial role in the body’s stress response; heart rate and blood pressure; and interleukins, which are inflammatory substances that play a role in the body’s immune system.
Research participants included 60 heavily impacted direct survivors of the Oklahoma City bombing, compared to a control group of local people who were not affected by the bombing. People in both groups were healthy.
The study found that, counterintuitively, cortisol levels were lower in people who survived the bombing. Survivors had higher blood pressure but a lower heart rate in response to trauma cues, suggesting their response may have become blunted over time.
Two interleukins were measured. Interleukin 1B, which is linked with inflammation, was significantly higher in survivors, and interleukin 2R, which plays a protective role, was lower.
“The main takeaway from the study is that the mind may be resilient and be able to put things behind it, but the body doesn’t forget. It may remain on alert, waiting for the next thing to happen,” said Phebe Tucker, M.D., lead author of the study and professor emeritus of psychiatry at the OU College of Medicine.
“We thought there would be a correlation between these biomarkers and the research participants’ psychological symptoms, but their PTSD and depression scores were not elevated and did not correlate with stress biomarkers,” she added.
“That tells us there is a stress response in the body that is not present in the emotions they express. In addition, the elevated interleukin 1B is typically seen in people with illnesses and inflammation, but this group was pretty healthy. However, it raises concerns about potential long-term health problems.”
Tucker and her colleagues have regularly conducted studies involving bombing survivors beginning soon after the event occurred. In this new paper, they are using data obtained seven years after the bombing. At the time, they did not study the same biomarkers, making this new study unique.
“Basically, what this paper shows is that after you’ve experienced severe trauma, your biological systems may not be at a typical baseline any longer; things have changed,” said study co-author Rachel Zettl, M.D., clinical assistant professor in the Department of Psychiatry and Behavioral Sciences, OU College of Medicine.
“It’s not just our minds that remember trauma; our biological processes do, too. It changes your actual physical being.”
Other authors of this paper were Betty Pfefferbaum, M.D., professor emeritus in the Department of Psychiatry and Behavioral Sciences, OU College of Medicine; Carol North, M.D., adjunct professor, University of Texas Southwestern Medical Center; Yan Daniel Zhao, Ph.D., professor, OU Hudson College of Public Health; Pascal Nitiema, Ph.D., Arizona State University; and Haekyung Jeon-Slaughter, Ph.D., University of Texas Southwestern Medical Center.
About this PTSD and neuroscience research news
Author: April Wilkerson
Source: University of Oklahoma
Contact: April Wilkerson – University of Oklahoma
Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Learning from Hindsight: Examining Autonomic, Inflammatory, and Endocrine Stress Biomarkers and Mental Health in Healthy Terrorism Survivors Many Years Later” by Phebe Tucker et al. Prehospital and Disaster Medicine
Abstract
Learning from Hindsight: Examining Autonomic, Inflammatory, and Endocrine Stress Biomarkers and Mental Health in Healthy Terrorism Survivors Many Years Later
Study Objective:
This unprecedented retrospective study explores long-term stress biomarkers in three systems in terrorism survivors.
Methods:
Sixty healthy, direct terrorism survivors were compared to non-exposed community members for cardiovascular reactivity to a trauma script, morning salivary cortisol, interleukin 1-β (IL-1β), and interleukin 2-R (IL-2R).
Survivors’ biomarkers were correlated with psychiatric symptoms and diagnoses and reported functioning and well-being seven years after the Oklahoma City (OKC) bombing.
Main outcome measures were the Diagnostic Interview Schedule (DIS) Disaster Supplement for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) diagnoses, Impact of Events Scale-Revised (IES-R), Beck Depression Inventory-II (BDI-II), Distress and Functioning Scale (DAF), and General Physical Well-Being Scale.
Results:
Survivors had higher inflammatory IL-1β, lower anti-inflammatory IL-2R, lower cortisol, higher resting diastolic blood pressure (BP), and less cardiovascular reactivity to a trauma script than comparisons.
Survivors’ mean posttraumatic stress (PTS) symptom levels did not differ from comparisons, but survivors reported worse well-being. None of survivors’ biomarkers correlated with PTS or depressive symptoms or diagnoses or reported functioning.
Conclusions:
Alterations of biological stress measures in cardiovascular, inflammatory, and cortisol systems coexisted as an apparent generalized long-term response to terrorism rather than related to specific gauges of mental health. Potential interactions of biomarkers long after trauma exposure is discussed considering relevant research.
Longer-term follow-up could determine whether biomarkers continue to differ or correlate with subjective measures, or if they accompany health problems over time. Given recent international terrorism, understanding long-term sequelae among direct survivors is increasingly relevant.