BDNF	Brain-Derived Neurotrophic Factor
CRP	C-Reactive Protein
HDRS	Hamilton Depression Rating Scale
HPA	Hypothalamic–Pituitary–Adrenal Axis
IFN-α	Interferon Alpha
IL	Interleukin
IL-1β	Interleukin-1 Beta
IL-2	Interleukin-2
IL-6	Interleukin-6
IL-10	Interleukin-10
JAK	Janus Kinase
KYN	Kynurenine
KP	Kynurenine Pathway
LPS	Lipopolysaccharide
MADRS	Montgomery–Åsberg Depression Rating Scale
MDD	Major Depressive Disorder
RCT	Randomized Controlled Trial
SSRI	Selective Serotonin Reuptake Inhibitor
tDCS	Transcranial Direct Current Stimulation
TNF-α	Tumor Necrosis Factor Alpha
TRD	Treatment-Resistant Depression