Depression is a common mood disorder that can be caused by a variety of reasons, with significant and persistent depression as the main clinical feature, and the depression is not proportional to its situation, and in severe cases, suicidal thoughts and behaviors may occur. Most cases have a tendency to have recurrent episodes, with most episodes resolving, and some may have residual symptoms or become chronic. Depression can occur in at least 10% of patients with manic episodes, at which point the diagnosis of bipolar disorder should be made. Also what we often call depression actually refers to clinical major depressive disorder, which affects 16% of the population at some point in their lives. In addition to the severe emotional and social costs of suffering from depression, the economic costs can be enormous. According to the World Health Organization, depression has become the world’s fourth leading disease, and is expected to become the second leading disease after coronary heart disease by 2020. Causes To date, the causes and pathogenesis of depression are not clear, and there are no obvious signs and laboratory abnormalities. Because the cause of depression is unknown, there are many hypotheses about the cause of depression. The probability of first-degree relatives having the disease is much higher than that of other relatives, which is consistent with the general rule of genetic diseases. 2, biochemical factors: catecholamine hypothesis, mainly refers to the occurrence of depression may be related to the brain synaptic gap neurotransmitter 5-hydroxytryptamine (5-HT) and norepinephrine (NE) concentration decline; due to many antidepressants, such as selective 5-hydroxytryptamine reuptake inhibitors (SSRI) or selective 5-hydroxytryptamine and norepinephrine reuptake inhibitors (SNRI) after the use of Although the concentration of these neurotransmitters in the synaptic gap of the brain rises quickly, the antidepressant effect generally still takes about 2 weeks to take effect, hence the hypothesis of increased sensitivity of 5-HT and NE receptors (hypersensitivity); 3. Psycho-social factors: the sudden occurrence of various major life events or their long-term persistence can cause intense or (and) persistent unpleasant emotional experiences, leading to depression The emergence of depression. According to the Chinese Classification and Diagnostic Criteria of Mental Disorders, Third Edition (CCMD-3), depression can be classified as mild depression or major depression according to the degree of impairment of social functioning; depression can be classified as “depression without psychotic symptoms” according to the presence or absence of “hallucinations, delusions, or stress syndrome”. Depression without psychotic symptoms and depression with psychotic symptoms; depression is divided into first-episode depression and recurrent depression according to whether there has been another depressive episode before (at least 2 months before). Once a patient is suspected of having depression, it is necessary to draw the attention of the patient and his family and go to a mental health institution for professional diagnosis and treatment in a timely manner. It is best to receive timely, adequate and thorough treatment (i.e., acute treatment to obtain clinical recovery, with adequate consolidation and maintenance treatment) once depression is identified, otherwise it will lead to chronicity and intractability of the disease. Disease treatment Once the diagnosis is established, a reasonable overall treatment plan should be formulated: in the acute phase, the first priority is to take strong measures to relieve the patient’s pain, relieve the symptoms and control the attack as early as possible; after controlling the symptoms during the acute attack to achieve recovery, a long course of treatment should be given, including preventing relapse, preventing recurrence and improving the prognosis. Treatment modalities for depression include medication, psychotherapy, and physical therapy.