The diagnostic basis of depression, also known as diagnostic criteria, is derived from psychiatric examination and observation of the patient’s mental activity. The diagnostic criteria of depression include the following: first, general criteria, that is, when depressive symptoms persist for more than two weeks and there are no manic or hypomanic episodes, in addition to excluding depression due to psychoactive substances and organic brain diseases. Second, the core symptoms of depression, including depressed mood, lack of interest, loss of pleasure, lack of energy, and excessive fatigue. Third, additional symptoms of depression, including low self-confidence and low self-esteem, self-blame or self-guilt, suicidal thoughts or behaviors, slowed thinking, inattention, unresponsiveness, inefficiency, and possibly excessive focus on one thing, sleep disorders, sexual dysfunction, appetite changes and corresponding changes in weight. Depression is diagnosed by meeting the general criteria, two core symptoms and two additional symptoms.