Fatigue during acute systemic inflammation is associated with reduced mental effort expenditure while task accuracy...

Area of Science:

• Neuroscience
• Psychology
• Immunology

Background:

• Previous research indicated physical inflammation alters motivational prioritization and effort allocation.
• It remains unclear if a similar motivational framework explains mental fatigue and cognitive symptoms during sickness.

Purpose of the Study:

• To investigate the relationship between fatigue, cytokines, and mental effort-based decision-making during acute systemic inflammation.

Main Methods:

• Eighty-five participants underwent a mental effort task post-lipopolysaccharide (LPS) administration.
• Cytokine levels (IL-6, IL-8, TNF) and fatigue were measured.
• Decision-making acceptance rates were analyzed using generalized estimating equations (GEE).

Main Results:

• Cytokine concentrations and fatigue increased 2 hours post-LPS.
• Mental effort acceptance rates decreased for medium-difficulty tasks, despite preserved accuracy.
• Reduced acceptance was linked to fatigue, not cytokine levels.

Conclusions:

• Fatigue during acute inflammation alters mental effort allocation, mirroring physical effort changes.
• Willingness to exert mental effort is influenced by effort level, not reward, during sickness.
• Findings support a motivational account of inflammation extending to cognitive effort, affecting general allocation processes.