The increased risk of suicidality in patients with MDD has been associated with inflammatory changes such as lowered BDNF or increased interleukin 1ß (IL-1ß), interleukin-6 (IL-6), interleukin-13 (IL-13), tumor necrosis factor α (TNF-α), C reactive protein (CRP) and C-C motif chemokine ligand 2 (CCL2), dysfunctions of the HPA-axis, with overproduction of CRH and elevated glucocorticoid production, and structural and functional brain changes [36,41,42] (Figure 1). Here, BDNF is linked to major depressive disorder.