The impact of inflammation on mood and brain function is still not yet entirely understood, but here’s what we do know. When we’re sick, our immune cells produce pro-inflammatory cytokines that affect the brain and our behavior through metabolic and molecular pathways that influence neurotransmitter systems. These systems can impact neurocircuits that regulate behavior, mainly through decreased motivation, avoidance, and alarm (anxiety).
During an unabated immune response, the pro-inflammatory cytokines IL-1β and tumor necrosis factor (TNF) begin to reduce the availability of serotonin, dopamine, and noradrenaline. These neurotransmitters are especially important for our mood regulation, playing an important role in anxiety modulation.