Abstract
Depression is one of the most common psychiatric diseases among people. In 2023 World Health Organization reports that 280 million people were diagnosed with depressive disorder which is 3.8% of the world population. It is believed that depression diagnoses will increase in the next few years. Moreover, it will be the most common disease in the world by 2030. Despite many studies, the pathomechanism of depression is not fully understood yet. Limitations in depression treatment include side effects and different response to treatment among patients. Proceeding in treatment-resistant depression is a challenge nowadays due to lack of definition, diagnosis criteria or therapeutic procedures. The deficit of guidelines for management of treatment-resistant depression results in decreased quality of health care and treatment efficiency.