Novel approaches for the management of depressive disorders

Major depressive disorder is a disabling psychiatric condition that causes a significant burden on individuals and society. There is still a lack of a clear understanding of the neuropathological changes associated with this illness and the efficacy of antidepressants is still far from optimal. Research into antidepressant therapies has evolved from serendipitous observation in human trials, but more than 60 years after the first monoaminergic antidepressants emerged they remain the mainstay for treating depression. However, glutamatergic modulators such as ketamine became the forefront of antidepressant exploration, especially for treatment-resistant depression and suicidal ideation. The glutamatergic hypothesis of depression is not new, however other NMDA receptor modulators do not seem to share the rapid and sustained effects of ketamine, suggesting that a unique combination of intracellular targets might be involved in its effect. Interestingly, inflammation can impact the glutamatergic system enhancing excitotoxicity and decreasing neuroplasticity. The points of convergence between the inflammatory and glutamatergic hypotheses of depression are not completely established, especially regarding the effects of fast-acting antidepressants. In this review, we discuss the most recent research surrounding glutamatergic fast-acting antidepressants, capable of modulating cellular plasticity and synaptogenesis and the potential of anti-inflammatory compounds evaluated from a different perspective. The combination of innovative ideas plus improvements on the discoveries made so far might lead to advances in antidepressant research with the promise of finding compounds that are both effective and fast-acting, even in patients who have tried other therapies with limited success.