Update on the pharmacological treatment of resistant depression

Resistance to major depressive disorder treatment causes distress to patients and their relatives, increases the number of hospital admissions, outpatient consultations, use of psychoactive drugs, and treatment costs. We review the concept and definition of treatment-resistant depression (TRD), different treatment methods, and comparative studies on treatment strategies. Despite its serious medical and psychosocial implications, the pharmacological treatment of TRD continues to be non-standardized and controversial. More research and comparative controlled studies on different treatments for resistant depression, which include neurobiological evaluations, need to be done.