Pre-existent anxiety symptoms is associated with modified behavioral response during endotoxemia

Abstract

Experimental endotoxin administration is a well-established model to analyze the effect of inflammation on the development of mood impairments. However, it remains unknown from previous studies in comparatively small samples whether pre-existing inter-individual differences modulate the behavioral response during endotoxemia. We addressed this question in the present study using a merged database combining data from multiple studies performed at two study sites. In 286 healthy volunteers who either received low-dose intravenous injection of lipopolysaccharide (LPS, 0.4–0.8 ng/kg, n = 168) or saline ( n = 118), plasma concentrations of TNF-alpha and IL-6 were analyzed before and 2, 3.5 and 6 hours post injection together with state anxiety symptoms (STAI). Pre-existent symptoms of anxiety and depression (HADS) were assessed before injection. LPS administration induced an increase in state anxiety 2 hours post injection that was positively correlated with increases in TNF-alpha and IL-6, but not with pre-existent HADS scores (when adjusted for age, sex, BMI, LPS dose, and study design). However, higher levels of pre-existent HADS anxiety symptoms predicted a stronger subsequent reduction in state anxiety at 3.5 and 6 hours post LPS injection. Taken together, these data suggest that although inter-individual differences in anxiety or depression symptoms do not appear to explain the extent of mood impairments during endotoxemia, at least in non-patient samples, they still lead to a modified mood response with a faster and stronger decline.