A new study has found that even if survivors’ physical and psychological scars have healed after experiencing trauma, their bodies can still carry a biological “imprint” of the event years into the future – the body doesn't forget.
The bombing of the Alfred P. Murrah Federal Building in downtown Oklahoma City (OKC) on April 19, 1995 – almost 30 years ago to the day – resulted in the deaths of 168 people and injured several hundred more. It’s regarded as the deadliest act of homegrown terrorism in US history.
We know that surviving such a traumatic event leaves physical and psychological scars, but what effect does it have on the body’s biology? New research led by the University of Oklahoma (OU) suggests that the body continues to “remember” trauma long after it’s happened, even if physical and psychological issues have been resolved.
“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,” said Phebe Tucker, MD, professor emeritus of psychiatry at OU’s College of Medicine and the study’s lead author. “It may remain on alert, waiting for the next thing to happen.
Seven years after the OKC bombing, 60 otherwise healthy survivors had biological stress measures, physiological parameters (heart rate, blood pressure) and psychological symptoms in response to trauma cues taken. The researchers looked at cortisol (a stress hormone) levels and levels of cytokines, signaling proteins that modulate the immune response, including inflammation.
Two cytokines were measured: interleukin 1-β (IL-1β) and interleukin 2-R (IL-2R). The first acts like an alarm bell for the immune system, starting the inflammatory process when the body detects an infection or injury. The second’s main job is to boost the immune response as needed, especially to fight infections or cancer. It acts as an ‘on-switch’ for T cells, directing them to multiply and get to work, so plays a more protective role.
Survivors’ measurements were compared to a control group of 23 healthy adults not exposed to the bombing. Survivors’ PTSD and depression symptoms didn’t differ from those of non-traumatized participants. Counterintuitively, cortisol levels were lower in people who survived the bombing. Normally, when a person is stressed, the body releases more cortisol into the bloodstream, which causes increased blood pressure, heart rate and muscle tension. It’s all part of the so-called ‘fight or flight’ response. Survivors also had higher blood pressure but a lower heart rate in response to trauma cues, suggesting that their trauma response had become blunted over the years. Average IL-1β levels were significantly higher in survivors compared to the control group, whereas average IL-2R was lower.
“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,” Tucker said. “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.”
It’s the first time researchers have revisited data collected seven years after the bombing to investigate the effect of the event on biological stress markers. The findings are important, say the researchers.
“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 Zetti, MD, clinical assistant professor in the Department of Psychiatry and Behavioral Sciences at the OU College of Medicine. “It’s not just our minds that remember trauma; our biological processes do, too. It changes your actual physical being.”
The study was published in the journal Prehospital and Disaster Medicine.
Source: The University of Oklahoma
