Part 2 - Emotionally Traumatic Events

     Emotionally traumatic events have long been considered a cause of Fibromyalgia Syndrome (FMS). However, it has been difficult to attempt to do research in this area primarily because of a statistical peculiarity called Berkson’s bias. If you have read some of the other short reports you may have remembered reading about the odds ratio. The odds ratio is a number that simply tells you about the odds of having a disease or medical condition compared to something else. For example, if you smoke the odds ratio of developing a particular type of cancer may be 6.8 compared to someone not smoking. This simply means you are at almost seven times the risk of developing that cancer by smoking, or it appears at a frequency in smokers that is 700% greater than non-smokers – the numbers mean the same thing.

     Berkson’s bias applies to people with two or more separate medical conditions – say heart disease and diabetes. People with heart disease and diabetes will see their doctor more than someone with just one of those diseases simply because having both diseases usually means they have more problems with both diseases than if they had just one. Berkson’s bias can either falsely elevate or lower an odds ratio depending on whether two medical conditions influence medical care for the other. In the case of FMS, patients who also have a history of physical or sexual abuse or post-traumatic stress disorder may disproportionately seek more medical care. If you are a researcher seeing FMS patients, you may see those FMS patients with a history of physical or sexual abuse more frequently than patients without such a history – this would inflate the odds ratio. Given that the independent consequences of trauma, such as musculoskeletal pain, fatigue, and mood and sleep disturbances overlap with the major core symptoms of FMS, this can be an important bias that confuses the picture when researchers try to separate out cause and effect.

     Stress has also been associated with imbalances in hormones and how the autonomic nervous system functions. Remember, the autonomic nervous system is largely responsible for all the unconscious actions of your body – breathing, heart rate, digestion, etc. A group of FMS researchers has shown that childhood physical abuse and sexual abuse both predicted abnormal cortisol responses in adult patients with FMS. Cortisol is the stress hormone of the body. Likewise, in adults studied immediately after trauma, disrupted cortisol levels are predictive of the later development of PTSD. These findings suggest there may be a neuroendocrine link between trauma, abuse, and dysruptions in the neuroendocrine axis affecting cortisol that could possibly begin in childhood – and that link may be tied to FMS.

     Three notable studies have provided support for an association of sexual and physical abuse and FMS, while two have not. FMS symptoms, if they are going to manifest, can develop up to 18 months after a traumatic event. A group of FMS researchers,  in 1997, compared FMS patients to those with rheumatoid arthritis and noted those with FMS had significantly higher lifetime prevalence rates of all forms of childhood and adult victimization as well as combinations of adult and childhood trauma. The strongest relationship was shown by FMS patients who had been physically assaulted in adulthood. It was also found that the severity of trauma could be correlated to measures of physical disability, psychiatric distress, the ability to adjust to illness, and the quality of sleep in FMS patients; but not to any of these characteristics in those patients with rheumatoid arthritis.  A psychiatrist specializing in FMS, Dr. Boudewijn Van Houdenhove, has found in FMS patients significantly higher prevalences of emotional neglect and abuse and physical abuse; he also identified a subgroup having experienced lifelong victimization. 

     Another group of FMS researchers has conducted the first community-based study of psychosocial trauma in FMS. The use of a community sample reduces the effects of something called reporting bias which is a significant factor when you try to study an issue this sensitive. Reporting bias means that people are reluctant to discuss certain aspects of their history with another individual because they are embarrassed, ashamed or otherwise uncomfortable but they will do so in an anonymous survey. They found that with the exception of actual rape, no self-reported sexual or physical abuse was associated with FMS; women who had been raped were 3.1 times more likely to be diagnosed with FMS.

     This was recently substantiated by a 2010 review that also found that two types of traumatic experiences, sexual assault and physical abuse, were associated with fibromyalgia. This study also looked at males with FMS.  Men with FMS experienced more life-threatening trauma while women had suffered more sexual assaults and abuse. No association was seen for other major life stresses, life threatening trauma, or emotional abuse and neglect.

     The first study examining post-traumatic stress disorder and FMS was published in 1997 and reported FMS in 21% of a group of 29 PTSD patients seen for care at a mental health clinic compared to normal control patients.  However, those PTSD patients with FMS were quite affected by the syndrome, much more so than other FMS patients, suffering pain, poorer quality of life, higher functional impairment, and psychological distress.

     In a 2000 study 56% of 93 FMS patients consecutively referred to a pain management center were found to have significant levels of PTSD-like symptoms.  As before, patients with both PTSD and FMS had significantly greater levels of pain, emotional distress, life interference, and disability with over 85% having significant disability. A separate study found PTSD symptoms in a similar percentage of patients – 57% of 77 FMS patients (40 women and 37 men).  In this study, FMS patients reported the single most important trauma to be the death of a loved one; this characteristic is similar to PTSD patients in general. 

     In regard to irritable bowel syndrome (IBS) and gastrointestinal reflux disease (GERD), both of which are frequently found in FMS patients, women with a history of sexual or physical abuse show a higher prevalence of gastrointestinal disorders. One study has shown abuse to be significantly more prevalent among those with GERD (92%) and IBS (82%). However, this study originated from an academic center and may reflect biases of more severe cases being sent to this center.

     Rather than PTSD being a risk factor for FMS, one FMS researcher, Dr. Karen Raphael and her group from the New Jersey Medical School, have proposed that women with FMS are at risk for PTSD not because they are exposed to more traumatic events compared to other women but because their biological nature makes them more susceptible to developing PTSD. They had the opportunity to test this hypothesis through a natural experiment that began with a community based study of family and psychiatric factors among women with FMS they conducted by telephone surveys. They contacted over 9,000 women in the Manhattan and nearby New Jersey area prior to September 11, 2001.

     After the attack, 2,026 of these participants were randomly contacted and assessed for pain and FMS like symptoms as well as PTSD symptoms. There was no significant increase in symptoms consistent with FMS.  However, after 9/11 the odds of probable PTSD were more than three times greater in women with FMS-like symptoms which were not reduced by controlling for FMS-like symptoms before 9/11. In other words, if a woman had FMS her risk of developing PTSD would be three times greater than a woman without FMS as a result of the 9/11 incident.

     Several studies have addressed the relationship between FMS and soldiers who served in the Gulf War but only two have shown an association. The Canadian Forces Personnel Health Study did not calculate prevalences but reported an odds ratio of 1.81.  The odds ratio of 1.81 means that Canadian soldiers who served in the Gulf War were almost twice as likely to develop FMS as those who did not.  The Iowa Persian Gulf Study found FMS prevalences of 19.2% in deployed veterans compared to 9.6% in non-deployed veterans using a telephone interview. Interestingly, PTSD was identified in only 1.9% of the combat veterans. Remember, the prevalence of FMS in the general population is about 3% - 4%; with 3% in females and 0.5% in males. You would say these numbers are exceptionally high and you would be correct. However, this was a telephone survey and did not include a physical exam. Consequently, there is a high risk for what are called, “false positives,” meaning individuals who test incorrectly positive for the criteria used over the phone for FMS.

     A much more extensive study was done by Dr. Bourdette and his group at the Portland Veteran Affairs Medical Center. They conducted a mail survey of 2022 veterans in the northwest U.S. From that mail survey they selected 443 individuals who agreed to come into their office for a clinic visit and then conducted a FMS examination on 241 patients randomly selected from this group. They calculated what are called minimum prevalence estimates, which means they assumed none of the control population would have FMS, so this would significantly underestimate their numbers. It would be like comparing a new anti-smoking product in a population that smoked to a reference population assuming none of that population smoked.

     Their minimum prevalence estimates of FMS, (remember - calculated assuming none of the non-responders would have FMS), were 2.47% total and 7.4% female and 1.8% male. These prevalence figures are similar to general community estimates of 2.8%.  A very large study conducted by physicians who worked for the Department of Defense looked at all hospitalizations in the Department of Defense medical facilities from October 1988 through July 1997. Gulf War veterans were found to be at a slightly greater risk for FMS, approximately 1.2 times greater. However, the researchers then looked at the conditions the soldiers had before they went into the war, which was possible because the Department of Defense keeps very good medical records on soldiers. Then there was no association. They did find the FMS was three times more common in females than males. Overall, it seems that even though studies show higher rates of PTSD in veterans there is no evidence of also having FMS.

     However, just like in non-soldiers, FMS exacerbates the symptoms of PTSD.  When the symptoms in individuals with both FMS and combat related PTSD were examined it was found those individuals with PTSD had more severe PTSD symptoms than veterans without FMS.  A recent 2010 study describes a chronic musculoskeletal pain syndrome in veterans where those afflicted, similar to FMS patients, reported naturally occurring exercised induced muscle pain as more intense. These individuals were also more sensitive to experimentally applied heat stimulation before and after acute exercise compared to normal control individuals.
The latter finding reflects a phenomenon termed exercised-induced hypoalgesia, in which exercise in healthy individuals renders them less sensitive to experimental pain. In other words, after people exercise heavily they tend to me more tolerant of painful stimulation. This is thought to be due to the natural release of endorphins. In patients with FMS, the opposite is found and patients become more sensitive to pain during and after exercise.

     Perhaps the ultimate test of PTSD is that of the Holocaust. A study by a group of FMS researchers has identified a significantly increased prevalence of FMS among Holocaust survivors who have now lived over six decades after the end of World War II. In survivors of the Nazi Holocaust 24% have developed FMS compared to age matched controls not exposed to Nazi occupation. A rather remarkable finding, and perhaps the best test to date regarding exposure to a traumatic situation and FMS.