A Review of Literature on Chronic Fatigue
Aggarwal et al (2005) highlights chronic as one of the health problems that are frequently unexplained for various reasons including a tendency to co-occur with other conditions. The etiology of chronic fatigue remains a quagmire with biological and environmental factors being mentioned as causal factors. Assessing the relationship between different environmental and psychological conditions remains one of the aspects that can be followed to explain chronic fatigue. Although important contributions of child trauma, harsh life experiences and somatosensory amplification to the development of chronic fatigue have been examined by several researchers, these studies are still lacking especially in the link between these factors. This review of literature examines the existing knowledge on chronic fatigue as contributed by somatosensory amplification, child trauma and threatening life experiences. The possible interrelationships are thereby described thus forming a strong basis for research into the role of the three variables in chronic fatigue.
Previous studies have concluded that certain traumatic events that an individual experiences during childhood increase the risk of developing a myriad of health conditions. Romans et al (2002) conducted a community-based study in New Zealand and identified a link between childhood traumatic disorders and several health conditions. In individuals who experienced at least one childhood adverse treatment, chronic fatigue was among the potential medical conditions that resulted. Despite this study highlighting the existence of a relationship between child trauma and chronic fatigue, the study does not highlight the causal relationship this provoking the need for research in this interplay. McCauley et al (2007) also reported physical and sexual abuse during childhood as a trigger of a number of health problems later in life. In this study, the authors highlighted that somatization scores were high in women who had been abused physically or sexually during childhood. The somatosensory amplification scale therefore proves an important tool for identifying increased somatization which can help identify the causal link between child trauma and chronic fatigue.
The etiology of chronic fatigue is not well characterized. Most studies have focused on the biological aspects of chronic fatigue while pay little attention to the environmental causes of the same. A few studies cite stress as a risk factor for development of chronic fatigue. For instance, a twin study conducted by Kato et al (2006) concluded that premorbid stress acts as a trigger for chronic fatigue and emotional instability is among the highest causal factor. This prospective study, just like many other studies, fails to highlight any the association between premorbid stress and chronic fatigue as a somatization process. However, the important question of intertwining chronic fatigue and earlier distressing experiences is highlighted from the finding that chronic fatigue tended to develop 25 years after an emotional instability.
From the view that child trauma has been mentioned in a number of studies as a risk factor for chronic fatigue syndrome (Heim et al, 2009; Yehuda, Halligan and Grossman, 2001), interest in the relationship between child trauma and chronic fatigue is raised. Since childhood illness is a form of physical trauma, it suggests a relationship between childhood trauma and chronic fatigue. In a twin study conducted by Roy-Byrne at al (2002), it was identified that chronic fatigue is mainly caused by environmental factors as opposed to biological factors. It is on this basis that there is need to explore some environmental factors such as child trauma and traumatic life experiences as causal factors in chronic fatigue.
Threatening life experiences are experiences can result into trauma regardless of the stage of life in which they occur. Such experiences have the possibility of causing physical as well as psychological harm. The psychological outcomes of stressful life events have been examined with anxiety and depression being the main areas of focus. The possibility of developing chronic fatigue has however been only slightly highlighted with authors such as Spinhoven and Verschuur (2006) indicating life disasters as causal to chronic fatigue. These authors present somatization as a possible though a minor pathway to development of chronic fatigue in rescue workers. In particular, Spinhoven and Verschuur noted that chronic fatigue is only slightly an outcome of somatosensory amplification. These findings tend to contradict Nakao & Barsky (2007) who highlight that somatosensory amplification is an important aspect of examining the etiology of chronic. It therefore follows that studying the levels of SSAS in individual suspected to suffer from CF would clear this matter.
Somatosensory amplification is the “the tendency to experience somatic and visceral sensations as usually intense, noxious, and disturbing” (Sayar, Barsky and Gulec, 2005, p. 340). ). The Somatosensory Amplification Scale (SSAS) is used to evaluate amplification and it has the ability to identify individuals who tend to magnify rather weak bodily sensations instead of normalizing them. Chronic fatigue is characterized by somatic symptoms, thus psychosomatic amplification can be used to assess the severity of chronic fatigue. Psychosomatic conditions such as chronic pain and psychiatric disorders can be monitored using SSAS thus laying a basis for establishing the severity of chronic fatigue. Psychiatric disorders such as posttraumatic stress disorder and major depression are mentioned as factors that increase risk of chronic fatigue. As such, there is a possibility of relating certain psychiatric disorders that are evaluated using SASS to chronic fatigue (Nakao & Barsky, 2007). In other conditions such as fibromyalgia, Geisser et al (2008) identified that somatosensory amplification can be used to identify comorbidity between chronic fatigue and fibromyalgia.
In view that somatosensory amplification is associated with chronic fatigue; there exists a complex interplay between likely causes of chronic fatigue and somatosensory amplification. It is expected that somatosensory amplification scores would be high in persons with a history of child trauma as well as persons who have experienced life threatening events. In specific, persons with child trauma may tend to exaggerate illness and view somatic sensations as disturbing thus raising somatization. The effect of these two variables would be to cause more risk factors for chronic fatigue. Traumatizing life events would also trigger somatization directly and indirectly. Directly, threatening life events tend to raise somatization since individuals perceive visceral sensations as intense. Indirectly, traumatizing events lead to trauma thus if they occur in childhood, they are considered as child trauma which heightens somatization. The overall effect is to increase chances of acquiring chronic fatigue.
Figure 1: A graphical model representing the complex interplay between somatosensory amplification, child trauma, life threatening experiences and chronic fatigue.
Persons suffering from chronic fatigue will have higher SA, LTE and CT scores compared to persons who do not suffer from chronic fatigue.
Individuals who suffer from fatigue but do not have CF will have lower SA, LTE and CT scores.
Individuals suffering from chronic fatigue will have a higher likelihood of developing chronic fatigue syndrome after a six months period compared to individuals who do not suffer from chronic fatigue.
Pearson correlation will be used to establish the relationship between chronic fatigue and SA, chronic fatigue and LTE and chronic fatigue and CT scores. It will also be used the scores in individuals who do not have chronic fatigue. To compare means scores for SA, LTE and CT in chronic fatigue patients and patients who do not have chronic fatigue, analysis of variance (ANOVA) analysis will be done. Multiple regression analyses will be utilized to analyze contribution of CT, SA and LTE in development of chronic fatigue syndrome. Dependent t-test will be used to test the significance of presence or absence of chronic fatigue in the development of chronic fatigue syndrome over a six months follow-up. All analyses will be performed at 95% confidence interval and p<.05 significance level.