SMPD1 and depressive disorder: ASMase is known to play a role in neural pathophysiology, as its activity has been linked to depression, BBB disruption, and ROS production, and it is activated by various stimuli such as lipopolysaccharides (LPS), oxidative stress, excessive cationic toxicity, lipid and tumor necrosis factor α (TNF-α), etc. [15,16,17].