Date sent: Wed, 23 Jan 2002 Chronic Fatigue Syndrome in Psychiatric Patients: Exposure to Potentially Toxic Substances J of Chronic Fatigue Syndrome, Vol. 10(1) 2002, pp. 37-53 Noble A. Endicott, MD Noble A. Endicott is Research Psychiatrist, Department of Research Assessment and Training, New York State Psychiatric Institute. Address correspondence to: Noble A. Endicott, 200 East 78th Street, Apartment 7C, New York, NY 10021. The author wishes to thank John Nee, PhD, for the statistical analysis, Jean Endicott, PhD, Claire Theroux, MPA, and Melissa Smith-Cockerham, MA, for making the ratings on the REPTSRS. ABSTRACT. Several investigators have suggested that environmental chemicals or "pollutants" play a significant role in the pathogenesis of chronic fatigue syndrome (CFS). This study compares the reported exposures to environmental chemicals and other potentially toxic environmental factors of psychiatric patients with CFS and two sets of controls from the same practice who did not meet the criteria for CFS. All comparisons found that CFS patients reported significantly more exposures to potentially toxic substances than any of the control groups. The extensive scientific literature on chemical intolerance and sensitization to generally non-toxic levels of potentially toxic substances, and its possible relevance to the investigation of CFS, is discussed. KEYWORDS. Chronic Fatigue Syndrome, toxic substances, chemical sensitization, chemical intolerance The etiology of chronic fatigue syndrome (CFS) remains unknown. However, a number of hypotheses regarding the pathogenesis of this condition have been advanced (1-4). Mechanic, in commenting on these issues in a discussion period during the Ciba Foundation Symposium on CFS, noted: ". . . If you took a group of people who met the criteria for major depression, and asked what proportion of such people also met the criteria for CFS, you would probably find a relatively small proportion. This would mean that your fatigued population is really a quite different population from the people with major depression, and one should know how they differ. Are they simply different because this particular group makes a different set of attributions about the nature of their illness, or are they different in other, fundamental ways?" (5). The present report is the fourth in a series of investigations of a group of psychiatric patients with CFS and controls from the same psychiatric practice, matched for psychiatric diagnosis (primarily major depression), which attempts to provide preliminary data relevant to Mechanic's question (6-8). A number of investigators have suggested that reactions to environmental chemicals, pesticides, or other "pollutants" may play a role in the pathogenesis of at least some cases of CFS (9-15). Buchwald and Garrity compared groups of 30 patients each with CFS, fibromyalgia, and multiple chemical sensitivities. The groups were similar in demographic characteristics and specific symptoms. For example, 60 to 90 percent of the groups were female, and all three groups had a large overlapping of symptomatology. Partially because of the striking similarities between these three conditions, the investigators noted: "Despite their different diagnostic labels, existing data, though limited, suggest that these illnesses may be similar, if not identical conditions ... In fact, the diagnoses assigned to patients with one of these illnesses may depend more on the chief complaint and the type of physician making the diagnosis than on the actual illness process" (9). Dunstan et al. compared serum organochlorine levels in 22 CFS patients, 17 patients with a syndrome similar to CFS and a history of exposure to organochlorine chemicals, and 34 matched non-CFS controls (11). Detectable hexachlorobenzene was present in the sera of 45 percent of the CFS patients (p < 0.05), 47 percent of the organochlorine chemicals exposure group (non-significant), and 21 percent of the controls. The CFS group also had significantly higher mean total organochlorine and DDE (a metabolite of DDT) levels than did the controls. The sera levels of these toxins were not significantly different in the patients with CFS and CFS-like patients with a history of exposure to organochlorine chemicals. On the basis of these findings, the authors suggest that these chemicals may play an etiological role in CFS. The present series of studies is being carried out both in response to Mechanic's question and in order to investigate, in a preliminary manner, the hypothesis that CFS is a multidetermined phenomena. While the author believes that exposure to environmental chemicals is a major contributing factor to the pathogenesis of CFS, this is not thought to be the sole "cause" of this disorder. While chemical exposure may be a primary etiological factor in some, perhaps most, cases of CFS, it is believed that hereditary (16) and/or other environmental (1-4), and/or central nervous system organizational factors (7) also contribute to the pathogenesis of CFS in the majority of cases. This presentation compares the extent of reported exposures to environmental chemicals, pesticides, medications, household cleaning agents (respiratory and/or oral ingestion), materials used by artists of a chemical nature (paints, solvents, paint thinners, etc.), and other potentially toxic environmental factors (mold, dust, cigarette smoke, etc.) of 46 psychiatric patients with CFS and 46 matched controls from the same psychiatric practice who did not meet the criteria for CFS. This control group (C-I) was chosen on the basis of good physical health. A second comparison was made between 33 CFS patients, 33 C-I controls and 33 C-II controls. The latter group was also matched with the CFS patients and were selected without regard to their physical health. © 2002 by The Haworth Press, Inc. All rights reserved. [Copies of the complete article are available for a fee from The Haworth Document Delivery Service: 1-800-342-9678. 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