Depressive episodes are dominated by a depressed mood, which is not proportional to its situation and can range from moping to grief and even malaise. In severe cases, psychotic symptoms such as hallucinations and delusions may occur. In some cases, anxiety and motor agitation are significant. Symptom Criteria】Mainly depressed mood with at least four of the following: 1. loss of interest, no sense of pleasure; 2. loss of energy or fatigue; 3. psychomotor retardation or agitation; 4. low self-esteem, self-blame, or feelings of guilt; 5. difficulty in association or reduced ability to think; 6. recurrent thoughts of death or suicidal or self-injurious behavior; 7. sleep disorders, such as insomnia, early awakening, or 8. decreased appetite or significant weight loss; 9. decreased sexual desire. Severe criteria: Impaired social function, causing pain or adverse consequences to the person. The criteria for the course of the disease: 1, meet the symptom criteria and severity criteria has lasted at least 2 weeks. 2.Some schizophrenic symptoms may be present but do not meet the diagnosis of schizophrenia. If both symptom criteria for schizophrenia are met, the depressive episode criteria are met for at least 2 weeks after the schizophrenic symptoms have resolved. Exclusion criteria: Exclude organic psychiatric disorders, or depression due to psychoactive and non-addictive substances. Note: This depressive episode criterion is only applicable to the diagnosis of a single episode. (1) Mild depressive disorder (mild depression) The episode meets all the criteria for a 32 depressive episode except that there is no impairment of social functioning or only mild impairment. (2) Depression without psychotic symptoms All criteria are met except for the addition of “no psychotic symptoms such as hallucinations, delusions, or catatonia syndrome” to the criteria for 32 depressive episodes. (3) Depression with psychotic symptoms All criteria were met except for the addition of “psychotic symptoms such as hallucinations, delusions, or catatonia syndrome” to the criteria for 32 depressive episodes. (4) Recurrent depressive disorder Symptom criteria: Recurrent high or low mood, but not meeting the criteria for manic or depressive episodes. Severity criteria: less impaired social function. Disease duration criteria: meet the symptom criteria and severity criteria for at least 2 years, but in these 2 years, there can be several months of normal intervals of mood. Exclusion criteria: 1. The change in mood is not a direct consequence of somatic illness or psychoactive substances, nor is it an additional symptom of schizophrenia and other psychotic disorders; 2. Manic or depressive episodes are excluded, and other types of affective disorders are diagnosed once the corresponding criteria are met. Symptom criterion: persistent depressed mood, but not meeting any of the symptom criteria of type I depression, as well as the absence of manic symptoms. Severity criteria: less impaired social functioning and complete or more complete self-awareness. Course of disease criteria: meeting the symptom criteria and severity criteria for at least 2 years, and in these 2 years, there is rarely an interval of normal mood lasting 2 months. Exclusion criteria: 1. The change in mood is not a direct consequence of a somatic disease (e.g., hyperthyroidism), or a psychoactive substance, nor is it an additional symptom of schizophrenia or other psychotic disorders; 2. All types of depression (including chronic depression or cyclothymic affective disorder) are excluded, and once the corresponding criteria for other types of affective disorders are met, the corresponding diagnosis of other types should be made; 3. Depressive personality disorder is excluded .