Two studies published in the November 6, 2006, issue of the Archives of General Psychiatry associate trauma in early life with CFS and CFS-like illness. However, each study has important limitations to consider and the authors’ conclusions should not be overgeneralized.
Both new studies focused on a narrow set of adverse events and excluded others, such as infection, serious injury and malnutrition, shown to be important in other conditions, and that warrant further exploration in CFS as well.
Adverse events in early childhood have been shown to be predisposing factors in other serious conditions, including cardiovascular disease, diabetes and depression. A report compiled by the National Scientific Council on the Developing Child at http://www.developingchild.net/papers/excessive_stress.pdf summarizes this literature in layman’s terms. No broader discussion of this literature is included in either paper and thus is being overlooked by the media.
Studies like these that rely solely on unverified self-report of childhood experiences occurring 35-50 years earlier, particularly of people with later-life physical and psychological health issues, have many limitations that are well-documented in the medical literature. Although the mean age of subjects in the Heim study was 50.5 years and subjects in the Kato study were 42 years or older, this limitation is only acknowledged in the Kato paper, as described below.
Christine Heim, PhD, of Emory University is the lead author of a study titled, "Early Adverse Experience and Risk for CFS: Results from a Population-Based Study." She is no longer affiliated with the Centers for Disease Control and Prevention’s CFS Research Group. Dr. Heim describes the small study of 43 CFS patients as "exploratory" and states that results "should be considered as preliminary." The researchers found that CFS cases reported significantly higher levels of childhood trauma and psychopathology compared to healthy controls. Exposure to childhood trauma was associated with three-to eight-fold increased risk for CFS across the trauma types assessed. The authors state, "our results also clearly demonstrate that not all cases of CFS have a history of childhood trauma."
The second study, by Kenji Kato, PhD, et al., of the Karolinska Institutet, presents similar findings from a study nested within a Swedish Twin Registry of 19,192 twin pairs born between January 1, 1935, and December 31, 1958. All twins were screened for the symptoms of CFS by telephone, but investigators did not conduct thorough physical and mental status exams to confirm CFS diagnosis. Thus, conclusions are based on "CFS-like illness," and not CFS as strictly defined. In all, 447 subjects fit the description of "CFS-like illness." Study results indicate an association between "emotional instability" and self-reported stress and chronic fatigue/CFS-like illness. In examining differences between twin pairs, the researchers reported that, "certain genetic propensities may ameliorate or exacerbate the effect of stress. At the same time, genetic influences on emotional instability also contribute to the development of fatiguing symptoms." The authors state that "a number of cases might have been misclassified owing to recovery or recall bias by the time of the interview."
As the November 3, 2006, announcements by CDC director Dr. Julie Gerberding underscore, the important story about CFS is much larger than any single study or pair of studies. The media coverage over the last week, of which only a small fraction relates to these studies, reflects the bigger picture too. That said, all people, including the subset of CFS patients described by these studies, whose lives have been affected by trauma in their childhood years certainly deserve compassion and careful study so that the biological and psychological impact of these early-life events is better understood.