Stress and Health

I am frequently asked if stress causes disease. Stress, I believe, has a huge psychological impact, and maladaptive behaviors in which we often engage in response to stress (such as smoking, overeating, excessive alcohol consumption, excessive rumination, etc...) can have extreme effects on one's physical health. Thus, potential treatment of stress may focus not only on reducing the stress-inducing events themselves, but also on one's response to such an event.

One of the organizations most interested in the physical and psychological impact of stress on the individual is the military. Military soldiers such as special operation forces who have a high probability of being behind enemy lines are often trained in intensely stressful situations with the hope of developing “stress inoculation.” Similar to vaccination theory, in which one is inoculated from a potential disease by vaccination with the virus and allowing one's immune system to fight it, stress inoculation hopes to build hardier soldiers to allow them to survive stressful situations associated with war.

One of the most stressful situations soldiers can experience is a course called Survival, Evasion, Resistance and Escape (SERE) at Fort Bragg's JFK Special Warfare Center. The SERE course is designed to simulate the evasion of an enemy, and if caught, to simulate a prisoner of war experience. Yale University's Dr Morgan, a researcher for the National Center for Post Traumatic Stress Disorder, studied 109 participants in the course.  Dr Morgan, et al. published their work with the title “Hormone Profiles in Humans Experiencing Military Survival Training” in 2000 in the Journal of Biological Psychiatry (2000:47: 891-901). They studied the salivary levels of cortisol and serum levels of testosterone at various stressful episodes of the training. Cortisol is a hormone released from the adrenal glands, which release carbohydrates for use by the brain. Testosterone is the primary male sex hormone.

In examining these individuals during stressful situations, researchers found that cortisol levels increased, while testosterone decreased. There was a change in the cortisol and testosterone during the escape and evasion, but the greatest changes in these hormones occurred when the soldiers were captured and underwent interrogation. During captivity and subsequent interrogation, testosterone levels could decrease to castration levels within 8 hours; the soldiers became effectively sterile during such episodes.

This study and others like it demonstrate that physical and psychological stress can have a profound biochemical effect on the body. It appears that this psychological impact is activated by a small walnut-sized organ in the middle of our brain called the amygdala. The amygdala analyzes for potential threats. If a threat is perceived, then messages are sent to the hypothalamus to release the fight or flight hormones.

From Wiki

It appears that there can be imprinting of a fearful event on the amygdala during a stressful situation. Thus, experiences that remind the amygdala (even unconsciously) of the stressful event can activate the amygdala to send a signal to the hypothalamus to release a cascade of fight/flight hormones. It is similar to someone who is having a panic attack. That person is convinced there is impending doom about to affect them. “Rationality” or “reason” are rarely effective during the acute attack, because one's body is currently being flooded by an activated amygdala subjecting oneself to a cascade of stress hormones.

People can respond to stressful events in different ways.  For instance, many smokers state that they smoke more in response to stress. Smoking releases dopamine, which is a “feel good” hormone. One can understand the desire for the cigarette in the effect that it has on dopamine release. However, when the dopamine wears off, the smoker often feels the need to smoke another cigarette to replenish the dopamine. This often creates a vicious cycle.

Are there other, more healthy means to decrease the impact of an activated amygdala? Actually, our frontal cortex is filled with inhibitory neurons, that, if activated, can calm an over-excited amygdala.  One activity that can help "turn down" the amygdala is meditation.  Meditation activates the inhibitory neurons from the prefrontal cortex and frontal cortex.  When functional MRIs (MRI scans that are performed with radioactive glucose that goes to areas of increased activity) are performed on skilled meditators, the activity in their frontal cortex and prefrontal cortex "light up."

There are various meditative techniques one can use to "silence the amygdala."  Often it is an attempt to decrease the constant inner voice chatter that occurs in our minds, most of which is negative, and allow a more contemplative, passive process.  Dr. Harold Benson, a cardiologist from Harvard, wrote The Relaxation Response in the mid-1970s and still has courses for physicians and other healthcare providers at Harvard.  His technique is at this website.  Christians may find Father Thomas Keating's Centering Prayer helpful; here is a website that offers PDFs that describe his process.  Thich Nhat Hanh, a Buddhist monk who has written extensively on meditation, has a short essay here on one of his simple, yet potentially powerful techniques.