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The Biology of War-Zone Stress Effects

In Odysseus in America:  Combat Trauma and the Trials of Homecoming, Jonathan Shay wrote that “The symptoms caused by psychological injury that the American Psychiatric Association calls PTSD in its Diagnostic and Statistical Manual of Mental Disorders (DSM) can be understood in one clear and simple concept:  persistence of valid adaptations to danger into a time of safety afterward” (Shay, 2002, p. 149).

In the war zone, the Service Member’s body and brain adapt to danger, remaining on high alert night and day, even when no attack is taking place.  As more than one veteran has said in interviews and presentations, “Even when it’s safe, it’s not safe.”The amygdala is in its element, issuing a standing order for the body’s stress systems to pump out sympathetic (“fight or flight”) and parasympathetic (“shut down, numb out, freeze”) chemicals.

Both “real-time” experience and the frequent triggering of the amygdala’s stored fragments of intense memory set off or “kindle” powerful sympathetic chemical reactions, which burn the message of threat into the brain, over and over again.  The more intense this process grows, the more it can seal the amygdala’s emotional memory fragments—sights, sounds, smells, feelings—into the unconscious.  And the more anxiety and insomnia this produces, the stronger the urges may be to seek sedation in alcohol, depressants, or marijuana.

On the parasympathetic side, these chemicals can:

  • Shut down and “numb off” important emotions
  • Create a sense of unreality, separation, and alienation
  • Keep the hippocampus from storing conscious memories of intense experiences, including traumatic events
  • Create patterns of avoiding any thoughts, feelings, or situations that might set off the chemical stress responses
  • Create an overpowering desire for substances that will provide any sort of stimulation or mood elevation

However, at least one parasympathetic chemical, gamma-aminobutyric acid (GABA), may protect people from developing chronic PTSD and help them recover from trauma (Vaiva et al., 2006).

Many service members and veterans have used the metaphor of having “one foot on the gas and the other on the brake.”  This makes perfect sense in light of the amygdala’s tendency to trigger and sustain overloads of both the sympathetic and the parasympathetic chemicals.

Of course, these basic survival-related processes and chemical reactions are by no means the whole picture.  Researchers will probably never even be able to describe, much less to quantify, the role of the many other overwhelmingly powerful emotions of war—exhilaration, satisfaction, love of comrades, love of the mission, empathy, rage, grief, and guilt, to name a few.

To what extent these emotions may “feed into” the human stress system cannot be measured as long as everything is happening all at once, with threats to the organism’s survival living in the same body with the natural and intense responses of the mind, the heart, and the spirit.  For example, if you were collecting human remains from a roadside blast, how would your anger, grief, and other emotions mix in with your body’s natural revulsion to death—and the role of this experience in triggering the amygdala’s survival responses?  And how would your experience change if your body was in the habit of pumping high levels of sympathetic “fight-or-flight” chemicals, numbing parasympathetic chemicals, or both?

A number of things—bonding within the Unit, inspiring leadership, opportunities to talk about experiences, trips away from the war zone where they can “rest and reset”—can in some cases help slow down some of the runaway chemical processes.  But intense experiences, vulnerable stress systems, and the many powerful effects of long-term exposure to the war zone can still overwhelm all these mitigating factors.

Next: The Onset of War-Zone Stress Effects


The material on all of the Clinical Pages is taken directly from the draft version of Finding Balance After the War Zone:  Considerations in the Treatment of Post-Deployment Stress Effects, a manual under development for the Great Lakes Addiction Technology Transfer Center and Human Priorities.  This draft is copyright © 2008, Pamela Woll.  Reprint permission is universally granted, but attribution is requested.
Click here for References and Other Resources.
Click here to link to a PDF file of the current version of the clinician’s manual draft.
Click here to link to a PDF file of the accompanying booklet for veterans.

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