The main reason for depression is that depressed patients will have slow reaction time, which is clinically manifested by the feeling that the brain is like a paste, like rust, and the reaction is particularly slow, and it takes a long time to think about a certain problem before getting an answer. In addition, patients will have a lack of concentration, which often shows that the brain becomes dumber and less flexible than before. Patients with depression also show clinical manifestations such as low mood, low self-esteem, no plans for the future, reduced interest in fun, feelings of uselessness, incompetence, powerlessness, despair, self-guilt, self-blame, suicide and self-injury. Therefore, patients with depression should be observed in many aspects, especially for the symptoms of depressed mood, delayed thinking response and reduced volitional activity, which are still the core symptoms of depressed patients and should be paid special attention. For depression, once diagnosed, early diagnosis and treatment are recommended and clinical cure can often be achieved.