Abstract # 1713 Predictors of bodily sickness symptoms during experimental endotoxemia

Abstract

Patients with inflammatory conditions commonly suffer from non-specific bodily symptoms such as fatigue, widespread pain, and malaise. However, it remains unclear if these symptoms are driven by cytokines and/or psychological factors. Experimental administration of endotoxin (LPS) is an established model to induce a wide spectrum of behavioral and physical sickness symptoms. The aim of the present study was to identify predictors of LPS-induced physical sickness symptoms using multivariate regression analyses. Healthy volunteers (N = 128) were randomized to LPS (0.4 or 0.8 ng/kg) or placebo in published studies with identical protocols. Psychological state (state anxiety, positive mood) and trait variables (depression symptoms, trait anxiety, neuroticism, extraversion, coping skills) were measured along with plasma concentrations of IL-6, TNF-alpha, and cortisol. Non-specific sickness symptoms experienced during the acute (0–6 h post-injection) and late inflammatory (6–24 h post-injection) phases were assessed with the validated Generic Assessment of Side Effects (GASE). Results showed that LPS-treated subjects reported significantly more physical sickness symptoms. Symptoms during the early phase were predicted by decreases in positive mood and increases in IL-6 plasma levels, explaining 28.5% of variance in GASE scores. During the late phase, increases in cortisol, IL-6 and baseline depression were significant predictors, explaining 38.5% of variance. Hence, mood alterations may constitute a risk factor for physical sickness symptoms in inflammatory conditions.