Predicting response: serotonin reuptake inhibition.

The introduction of selective serotonin reuptake inhibitors (SSRIs) has helped clarify our understanding of the actions of serotonin in depression. The serotonergic network of the central and peripheral nervous systems comprises many different pathways and at least 14 distinct serotonin receptors. By using our knowledge of neuroanatomy and the pharmacology of SSRIs, it is possible to predict many of the therapeutic and non-therapeutic effects of modulating serotonin levels. The efficacy of SSRIs in mild to moderate depression is well established but their efficacy in severe depression varies, compared with tricyclic antidepressants. The SSRIs also have predictable effects in a range of other affective disorders including obsessive-compulsive disorder, anxiety and bulimia, the efficacy varying between the different SSRIs. The adverse event profile is different from that of the tricyclic antidepressants and again is predictable through an understanding of the different serotonergic pathways.