The Neurobiology of Stress and Emotions
By: Emeran A. Mayer, M.D., UCLA Mind Body Collaborative Research Center, UCLA School of Medicine, California
"What does this have to do with IBS
Converging evidence from different laboratories and research groups are consistent with the concept of an "enhanced stress responsiveness" as a major vulnerability factor in many IBS patients. As outlined above, such an enhanced stress responsiveness may not be obvious to the affected individual, until he or she is exposed to a period of sustained threatening stressors (financial or employment problems, divorce, aftermath of a major disaster with consequences on daily life), repeated mild to moderate stressors, or a one time severe (life threatening) type stressor (robbery or physical assault). Under these circumstances the mechanisms that normally turn off the stress response are overwhelmed, and attempts of the nervous system at adaptation or habituation fail. Many of the vulnerability factors for such enhanced stress responsiveness have been identified and many of them occur in a particular vulnerable period of the developing brain (before age 10). Some of the best-studied factors include loss of the primary care giver, distant mother-child relationship, emotional neglect, and physical and verbal or sexual abuse.
In order to understand how a chronically enhanced stress response can produce the cardinal symptoms of IBS (abdominal pain and discomfort associated with altered bowel habits) we have to go back to the earlier section on the emotional motor system: activation of the stress system will stimulate contractions and secretion in the sigmoid colon and rectum. Depending on the specific emotional context (fear vs. anger), the upper GI tract will be either inhibited (fear) or stimulated (anger). In addition, recent research in animals has demonstrated a phenomenon referred to as stress-induced visceral hyperalgesia. What this means is that in vulnerable animals, exposure to an acute moderate stressor will make the colon more sensitive to distension (and the perception of discomfort or pain).
"Perceptions of pain, muscle tensions, and other somatic symptoms can cause stress levels to spiral upward. Self-regulation strategies that reduce unpleasant symptoms offer both physical and psychological relief."
Why do the symptoms go away after one stressful situation has resolved and persist in another? Amongst many factors, anxiety and fear generated by IBSsymptoms themselves are sufficient in many patients to maintain the stress responsiveness in a chronically enhanced state. Some of the more common symptom related anxieties include: Am I close enough to a bathroom when my symptoms come on? Will I be OK for the rest of the day, unless I completely empty my colon in the morning before leaving the house? "
My website on IBS is www.ibshealth.com