Terrorism causes ‘bodily memories,’ long-term impact on biological stress

Key takeaways:

• Survivors had higher baseline diastolic blood pressure than controls but lower reactivity to trauma cues.
• Survivors had higher interleukin-1 levels vs. controls but lower interleukin 2-R and cortisol levels.

Medically healthy survivors of the 1995 Oklahoma City bombing had significantly different biological stress measures compared with adults who did not experience the bombing, years after it occurred, according to study results.

The study was published in Prehospital and Disaster Medicine.

“Clinicians should remember that individuals directly impacted by terrorism or trauma may have ‘bodily’ memories in stress measures despite being emotionally and physically healthy,” Phebe Tucker, MD, DLFAPA, professor emeritus and volunteer faculty for the department of psychiatry at University of Oklahoma Health Sciences Center, editor-in-chief of The Journal of the Oklahoma State Medical Association and medical director of the Oklahoma County Medical Society’s Physician Wellness Program, told Healio.

Previous studies show that terrorism and trauma survivors experience changes in autonomic, inflammatory and hypothalamic-pituitary-adrenal (HPA) axis biomarkers. Researchers have proposed that interactions between the central nervous system, immune system and endocrine system are crucial to the chronic stress response but have not examined these three systems in medically healthy people who experienced the same traumatic event, according to a related press release.

This inspired Tucker and colleagues to perform a novel long-term retrospective study of adults 7 years after they experienced the 1995 Oklahoma City (OKC) bombing, evaluating their cardiovascular reactivity to a trauma script and additional biomarkers including morning salivary cortisol, interleukin 1- (IL-1) and interleukin 2-R (IL-2R).

The researchers also assessed psychological stress symptoms via a revised version of the Impact of Events Scale-Revised (IMPOK), the Beck Depression Inventory-II (BDI-II) and a general physical well-being scale.

The analysis included 60 adult OKC bombing survivors (54.7% male; 86.8% white; mean age, 47 years) who participated in an earlier study of emotional and psychological functioning and 23 controls (46.1% male; 79.5% white; mean age, 42 years) recruited from the community.

Results showed that the survivors had significantly higher baseline diastolic blood pressure than controls (75.56 mm Hg vs. 68.26 mm Hg; P = .003). However, when exposed to trauma cues, survivors showed a significantly lower reactivity score in terms of heart rate (difference, 5.45 vs. 8.91; P = .017) and systolic (difference, 14.38 vs. 20.13; P = .036) and diastolic (difference, 8.28 vs. 11.26; P = .028) blood pressure. This “blunted” response may be due to the survivors’ higher baseline measures preventing a robust increase during testing, the researchers wrote.

Further, compared with controls, survivors had significantly lower mean morning cortisol levels (0.27 vs. 0.87; P = .022).

According to a multivariable liner model adjusted for gender, age, ethnicity and psychiatric diagnosis, survivors had greater average IL-1 than controls (116.76 vs. 98.3; P <.001) but lower IL-2R levels (435.7 vs. 503.17; P = .021).

Also, the researchers found that survivors viewed themselves as “significantly less well” than unexposed participants (4.3 vs. 4.93; P = .018), according to the general physical wellness scale. Difference in median BDI-II and IMPOK between survivors and controls did not reach significance.

Finally, Tucker and colleagues found that none of the biological stress measures correlated with psychological symptoms, including PTSD and depression, according to Spearman correlations and the Kruskal-Wallis test.

The researchers noted several limitations to this study, including the lack of periodic assessment of biomarkers after the OKC bombing.

Tucker was surprised at the lasting biological impact of the bombing on the survivors.

“We don’t know if this will be linked with later health problems or if it is part of the body’s being on ‘ready alert’ for future disasters,” Tucker told Healio.

Future studies should include survivors and controls with health problems, although this may lead to difficulties in interpreting cardiovascular reactivity measures, she added.

“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,” Tucker said in the release.

For more information:

Phebe Tucker, MD, DLFAPA, can be reached at phebe-tucker@ouhsc.edu.

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