It has been proposed that
major depressive disorder is near-identical with sickness behavior, so raising the possibility that it is a maladaptive manifestation of sickness behavior due to abnormalities in circulating cytokines.
[27][28][29] Moreover, chronic, but not acute, treatment with antidepressant drugs was found to attenuate sickness behavior symptoms in rodents.
[30] The mood effects caused by
interleukin-6 following an immune response have been linked to increased activity within the
subgenual anterior cingulate cortex,
[31] an area involved in the etiology of depression.
[32] Inflammation-associated mood change can also produce a reduction in the functional connectivity of this part of the brain to the
amygdala,
medial prefrontal cortex,
nucleus accumbens, and
superior temporal sulcus.
[31]