SAN FRANCISCO – Neurobiological effects of trauma persist for years and might help survivors better handle future trauma or increase their risk of cardiovascular disease and other problems, three studies suggest.
One study assessed 34 adult survivors of Hurricane Katrina who were relocated to Oklahoma 22 months after the hurricane, and compared them with 34 control participants in Oklahoma who matched the survivors’ characteristics. A second study assessed nine adolescent survivors who were relocated 22 months after Hurricane Katrina and nine matched controls. The third study compared 60 adults who directly experienced the Oklahoma City bombing (84% of whom were injured) with matched controls 7 years after the bombing.
Dr. Phebe M. Tucker
The results showed that autonomic, neuroendocrine, and immune system changes from trauma might last for years, even after emotional wounds have healed, Dr. Phebe M. Tucker reported in a press briefing and a poster presentation at the annual meeting of the American Psychiatric Association.
The survivors and controls differed in mean arterial blood pressure, heart rate, variability of heart rate, and levels of cortisol, a regulatory substance that promotes the fight-or-flight response; interleukin-2 (IL-2), which protects against infection; and interleukin 6 (IL-6), which promotes inflammation).
Some of these changes might enhance a person’s fight-or-flight response, and so could prepare survivors for future disasters, but the health implications are unclear, she said. Previous studies have linked trauma to increased cardiovascular and other health problems, such as a tripling in the myocardial infarction rate at Tulane University in New Orleans after Hurricane Katrina. The physiologic changes seen in the current studies might contribute to that.
The current studies also found more short-term and long-term neurobiological changes in survivors with depression or posttraumatic stress disorder (PTSD), compared with survivors without depression or PTSD or control participants.
In the study of adult survivors of Hurricane Katrina, 35% of survivors and 12% of controls had PTSD. Baseline heart rates were significantly higher among survivors (81 beats per minute), compared with controls (75 beats per minute). Survivors with or without PTSD had significantly higher levels of IL-6, compared with control participants who did not have PTSD, reported Dr. Tucker, chair of psychiatry at the University of Oklahoma Health Sciences Center, Oklahoma City. She conducted the studies with Dr. David H. Tiller, also of the university.
Survivors’ baseline sympathetic (fight-or-flight) heart rate variability was significantly higher – approximately double – that of the control group. The protective, parasympathetic heart rate variability at rest was significantly lower than in controls. When participants were exposed to reminders of the hurricane, the controls showed a significantly greater reaction in the parasympathetic heart rate variability, compared with a flat response among survivors, she said.
"Overall, the adult Katrina survivors’ higher heart rates, decreased protective heart rate variability, and increased inflammatory IL-6 may increase their risk for heart disease," Dr. Tucker said.
The pilot study of 18 adolescent survivors and controls (average age 15 years) found significantly higher rates of symptoms for PTSD or depression among survivors. As might be expected from previous studies of trauma and PTSD, the survivors had lower levels of cortisol, and IL-2 levels correlated with cortisol levels, suggesting that survivors might have reduced immune protection and could be more susceptible to infection, she reported.
In contrast with the adult findings, however, higher PTSD symptoms in the adolescents correlated with lower levels of the inflammatory cytokine IL-6. This might be because the youths lacked the inflammatory changes seen in adults after trauma or the youths were more resilient in some ways, she speculated.
In the third study of the bombing survivors, mean PTSD and depression symptom severity scores were below clinically relevant levels 7 years after the bombing. The handful of survivors who still had PTSD had significantly higher cortisol levels, compared with non–PTSD survivors and controls.
When exposed to reminders of the bombing, the survivors showed greater increases in heart rate, systolic and diastolic blood pressures, and mean arterial pressure. "Autonomic reactivity may be a generalized long-term response" to trauma that’s independent of PTSD, she said.
Dr. Tucker reported having no financial disclosures.
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