A Controlled Comparison of Multiple Chemical Sensitivities and Chronic Fatigue Syndrome

Abstract

The present study had two objectives: 1) to determine the characteristics that differentiated subjects with multiple chemical sensitivities (MCS), chemical sensitivities (CS), and chronic fatigue syndrome (CFS); and 2) to evaluate the psychiatric and neuropsychological complaints of these groups relative to normal controls. A cross-sectional comparison was made of the following groups matched for age, sex, and education: 1) patients whose sensitivities to multiple low level chemical exposures began with a defined exposure (MCS; N = 23); 2) patients with sensitivities to multiple chemicals without a clear date of onset (CS; N = 13); 3) patients meeting CDC criteria for Chronic Fatigue Syndrome (CFS; N = 18); and 4) normal controls (N = 18). Subjects with sensitivities to chemicals (MCS and CS) reported significantly more lifestyle changes due to chemical sensitivities and significantly more chemical substances that made them ill compared with chronic fatigue and normal controls. MCS, CS, and CFS patients had significantly higher rates of current psychiatric disorders than normal controls and reported significantly more physical symptoms with no medical explanation. Seventy-four percent of MCS and 61% of CFS did not qualify for any current Axis I psychiatric diagnosis. Chemically sensitive subjects without a defined date of onset (CS) had the highest rate of Axis I psychiatric disorders (69%). On the MMPI-2, 44% of MCS, 42% of CS, 53% of CFS, and none of the controls achieved clinically significant elevations on scales associated with somatoform disorders. With the exception of one complex test of visual memory, no significant differences were noted among the groups on tests of neuropsychological function. Standardized measures of psychiatric and neuropsychological function did not differentiate subjects with sensitivities to chemicals from those with chronic fatigue. Subjects with sensitivities to chemicals and no clear date of onset had the highest rate of psychiatric morbidity. Standardized neuropsychological tests did not substantiate the cognitive impairment reported symptomatically. Cognitive deficits may become apparent under controlled exposure conditions.

Multiple Chemical Sensitivity: A Test of the Olfactory-Limbic Model

“…The trend for the MCS group to report more anxiety and depression than asthmatic controls was not statistically significant The increase in anxiety and depressive symptomatology in the MCS group was consistent with case-series reports (Stewart & Raskin, 1985) and case-control studies (Black et al, 1990;Fiedler et al, 1996;Simon et al, 1990;1993).…”

Neuropsychological approaches for the detection and evaluation of toxic symptoms.

“…While some tests appear to be more sensitive than others, it is difficult to develop a clear picture due to the large variability in the demographic profiles of the subject groups evaluated, the range of different substances to which these groups were exposed, and the lack of clarity regarding duration and intensity of exposures. Despite these factors, several attempts have been made to develop batteries of tests that can be coordinated across studies [e.g., WHO battery (31), NES battery (16) (49,50). This is in contrast to the literature on the neuropsychological effects of neurotoxicants, which is based largely on men.…”

“…The challenge is to develop methodologies to measure these changes. Second, MCS patients have a higher rate of psychiatric disorder (e.g., depression, anxiety) concurrent with and before the onset of MCS (49,50). Many use this information to suggest that MCS is not a unique susceptibility but simply a psychiatric condition that is attributed to chemicals.…”

“…Only two studies to date have used standardized neuropsychological tests to evaluate the cognitive complaints of MCS patients (50,56 (57,58). These patients are similar to MCS patients in that they are otherwise healthy individuals who report sensitivities in response to indoor air mixtures that other individuals apparently tolerate.…”

“…This finding is consistent with the observation of hyperactive children of Weiss et (Figure 2). Health concerns measures a range of somatic symptoms, some of which can be related to neurologic conditions and some to somatization (69 (50,56). Little is known about how depression may interact with the effects of neurotoxicants in producing behavioral performance decrements.…”