Concomitant environmental chemical intolerance modifies the neurobehavioral presentation of women with fibromyalgia

Background: This study compared personality, dietary, and psychophysiological characteristics of 3 groups of women: fibromyalgia (FM) with illness from low levels of environmental chemicals (chemical intolerance, CI), FM alone without CI, and normal controls. CI may be a marker for enhanced central nervous system response amplification (sensitization) in limbic and mesolimbic pathways, which play a role in hedonic responses to food and drugs and in pain. Method: Fibromyalgic women with (FM/CI, n = 11) and without CI (FM, n = 10) and normals (NORM, n = 10) participated in the study. Measures included psychological trait questionnaires, a food frequency questionnaire, a taste test for hedonic and sweetness ratings of different sucrose concentrations, pain self-ratings, and resting spectral electroencephalographic alpha over midline sites, averaged over four separate days. Results: FM with CI had the highest scores on the Harm Avoidance dimension of the Tridimensional Personality Questionnaire, Carbohydrate Addicts Test, Limbic Symptom sensory and behavior subscales, and SCL-90-R somatization and obsessiveness subscales. FM groups both had the highest mean pain ratings for 21 tender point sites. Groups did not differ for macronutrient intake or for sweetness and hedonic ratings for sucrose. The combined FM groups had greater EEG alpha activity towards posterior midline sites than did normals. Conclusion: The pattern of findings may reflect impaired serotonergic function and/or elevated dopaminergic receptor activation by endogenous and/or exogenous agents. The data could have implications for pharmacological and dietary interventions in different subsets of FM patients.