Joshua Schrock

JOSHUA M. SCHROCK, then a graduate student at University of Oregon, Eugene, Oregon, was awarded funding in October 2017 to aid research on “Parasitic Infection, Sickness Behavior, and Immune Function among Shuar Forager-horticulturalists of Amazonian Ecuador,” supervised by Dr. J. Josh Snodgrass. Humans often experience low mood (e.g., fatigue, sadness) when sick. During infection, low mood may help the sick host prioritize immune function by reducing the energy spent on physical activity, thereby leaving more metabolic resources available for immune function. Inflammation-related immune pathways play a key role in generating changes in mood and behavior during infection. Experimental studies have demonstrated that acute inflammation can induce low mood. Previous studies have reported that individuals with chronic systemic inflammation are more likely to exhibit depressive symptoms (including low mood), though other studies have been unable to detect associations between inflammation and depressive symptoms. These inconsistent findings raise questions about the dose and chronicity of inflammation needed to induce low mood in real-world environments. This study tests whether greater systemic inflammation is associated with stronger feelings of fatigue, sadness, and sickness in a sample of Shuar forager horticulturalists in the Northern Amazon. Adjusting for key covariates, greater systemic inflammation was associated with stronger feelings of sickness but not fatigue or sadness. These findings suggest that systemic inflammation may generate internally detectable cues (i.e., feelings of sickness), even when the dose and chronicity of inflammation is insufficient to generate low mood.