Moreover, several studies have investigated that ECT and different classes of antidepressants such as the serotonin selective reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), and tricyclic antidepressants (TCAs) have effects on the peripheral BDNF in MDD patients [15–18]. The gene discussed is BDNF; the disease is major depressive disorder.