Key psychological processes associated with the fibromyalgia phenotype exist on a continuous spectrum with asymptomatic people.

Abstract

Background/Purpose: The core features of the fibromyalgia phenotype, the widespread pain and widespread tenderness, represent one extreme of a continuous spectrum with asymptomatic people at one end and those meeting criteria for fibromyalgia at the other. A number of key central processes associate with fibromyalgia, such as personality [neuroticism and Type A] and psychological characteristics, including attitude, control, coping, catastrophizing and stress-reactivity.We hypothesized that these psychologically linked processes also exist on a single continuous spectrum from normal in asymptomatic people to abnormal in fibromyalgia, and that increasing the "gain" of these processes will increase the features contributing to the fibromyalgia phenotype. Method(s): We identified 98 women with fibromyalgia diagnosed according to standard ACR criteria. Applied questionnaires included the Big 5 Personality Inventory, Type A scale, Fibromyalgia Impact Questionnaire, Perceived Control of Internal States, Mastery scale, the Coping Scale and Perceived Stress scale and the depression, anxiety, confusion and optimism scales of the Profile of Mood States questionnaire. Normallity assessment using Shapiro-Wilk test and correlations and regression modelling and comparisons between smallest and largest tertileswere used to explore the relationships between personality and psychological variables in both the healthy controls and in the patients with fibromyalgia. Result(s): There was a significant relationship between lower and higher tertiles of neuroticism, internal and external control, attitude, coping and stress and the characteristic fibromyalgia phenotype features of fatigue, sleep and confusion, in both the healthy control and the fibromyalgia groups [p all <0.001]. Pain was also significantly different in the healthy controls [p<0.001] but showed a non-significant ceiling effect between lowest and highest tertiles in the fibromyalgia group. Personality and psychological variables also correlated significantly in both healthy controls and fibromyalgia with depression and anxiety [p<0.001]. The absolute levels of all characteristics in healthy controls and fibromyalgia patients differed significantly [p<0.001].Normality plots indicated that the psychological characteristics examined existed on a spectrum with healthy controls at one end and fibromyalgia patients at the other. Conclusion(s): The personality and psychological variables that associate with fibromyalgia exist on a continuous spectrum, linking normal asymptomatic persons to the fibromyalgia phenotype.Increasing certain centrally important psychological variables will increase fibromyalgia clinical features. This is suggestive of a key role for central psychological factors in the pathogenesis of fibromyalgia.