HTR5A and major depressive disorder: This is perhaps unsurprising, as these drugs have abysmal clinical success in treating non-trauma elicited major depressive disorder and further act to indiscriminately increase synaptic levels of 5-HT by blocking the synaptic clearance of 5-HT, thereby increasing 5-HT receptor activation in an unbiased manner (Alex and Pehek, 2007; Jakobsen et al., 2017).