Consistently, high CYP2C19 enzymatic capacity has been associated with higher suicidality in individuals with depression who attempt suicide [34], whereas its absence was associated with lower levels in state markers of suicide, such as lower depressive symptoms [35], a lower prevalence of major depressive disorder and depression severity and increased bilateral hippocampal volume in healthy cohorts [34]. This evidence concerns the gene CYP2C19 and major depressive disorder.