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Chronic Fatigue: Literature Review and Hypotheses

Aggarwal et al (2005) highlight 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 individuals 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 childhood 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 childhood 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 paying little attention to the environmental causes of the same. A few studies cite stress as a risk factor for the 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 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 emotional instability.

From the view that childhood 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 childhood 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 et 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 a need to explore some environmental factors such as childhood trauma and traumatic life experiences as causal factors in chronic fatigue.

Threatening life experiences are experiences that can result in 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 minor pathway to the 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 individuals suspected to suffer from CF would clear this matter.

Somatosensory amplification is “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 the 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 childhood 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 the chances of acquiring chronic fatigue.

A graphical model representing the complex interplay between somatosensory amplification, child trauma, life-threatening experiences, and chronic fatigue.
Figure 1: A graphical model representing the complex interplay between somatosensory amplification, child trauma, life-threatening experiences, and chronic fatigue.


  1. Persons suffering from chronic fatigue will have higher SA, LTE, and CT scores compared to persons who do not suffer from chronic fatigue.
  2. Individuals who suffer from fatigue but do not have CF will have lower SA, LTE, and CT scores.
  3. 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.

Statistical analysis

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, an analysis of variance (ANOVA) analysis will be done. Multiple regression analyses will be utilized to analyze the contribution of CT, SA, and LTE in the development of chronic fatigue syndrome. A dependent t-test will be used to test the significance of the 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 a 95% confidence interval and p<.05 significance level.


Aggarwal, V. R., McBeth, J. Zakrszewska, J. M., Lunt, M. and Macfarlane, G. J. (2005). The epidemiology of chronic syndromes that are frequently unexplained: do they have common associated factors? Int. J. Epidemiol., 35 (2): 468-476. Web.

Geisser, M. E., Donnell, C. S., Petzke, F., Gracely, R. H. and Clauw, D. J. et al. (2008). Comorbid somatic symptoms and functional status inpatients with fibromyalgia and chronic fatigue syndrome: sensory amplification as a common mechanism. Psychosomatics, 49: 235-242.

Heim, C., Nater, U. M., Maloney, E., Boneva, R. and Jones, J. F. et al (2009). Childhood Trauma and Risk for Chronic Fatigue Syndrome. Arch Gen Psychiatry, 66(1):72-80.

Kato, K., Sullivan, P. F., Evengard, B. and Pedersen, N. L. (2006). Premorbid predictors of chronic fatigue. Arch Gen Psychiatry, 63:1267-1272

Sayar, K., Barsky, A. J. and Gulec, H. (2005). Does somatosensory amplification decrease with antidepressant treatment? Psychomatics, 46: 340-344.

McCauley, J., Kern, D. E., Kolodner, K., Schroeder, A. F. and DeChant, H. K. et al. (1997). Clinical characteristics of women with a history of childhood abuse. JAMA, 277(17):1362-1368.

Nakao, M. and Barsky, A. J. (2007). Clinical application of somatosensory amplification in psychosomatic medicine. BioPsychoSocial Medicine, 1:17. Web.

Romans, S., Belaise, C., Martin, J. Morris, E. and Raffi, A. (2002). Childhood Abuse and Later Medical Disorders in Women: An Epidemiological Study. Psychother Psychosom, 71:141-150.

Roy-Byrne, P., Afari, N., Ashton, S., Fischer, M. and Goldberg, J. et al (2002). Chronic fatigue and anxiety/depression: a twin study. British Journal of Psychiatry, 180, 29-34.

Spinhoven, P. and Verschuur, M. (2006). Predictors of Fatigue in Rescue Workers and Residents in the Aftermath of an Aviation Disaster: A Longitudinal Study. Psychosomatic Medicine 68:605-612.

Yehuda, R., Halligan, S. L. and Grossman, R. (2001). Childhood trauma and risk for PSTD: Relationship to intergenerational effects of trauma, parental PSTD, and cortisol excretion. Development and psychopathology, 13: 733-753.


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