Definition: A type of mood disorder with significant and persistent depressive symptoms as the main clinical feature caused by various causes. The core symptoms are depressed mood and loss of interest that are out of proportion to the situation.

Causes: 1. Heredity 2. Neurobiochemistry 3. Neuroendocrine 4. Neuroimaging 5. Neuroelectrophysiology 6. Psychosocial factors

Core symptoms: 1. Depressed mood: not commensurate with the situation 2. Loss of interest: no interest in doing things 3. Anhedonia: unable to experience pleasure from activities

Psychological symptom cluster: 1. Slow thinking: the speed of thinking and association slows down, and self-perceived brain reaction is sluggish 2. Cognitive function impairment: reduced attention, prolonged reaction time; reduced abstraction and generalization ability, reduced learning ability, and worsened speech fluency 3 , Negative cognitive model: three nothings (hopelessness, helplessness, worthlessness) 4. Self-blame and self-guilt 5. Suicidal ideation and behavior 6. Psychomotor retardation or agitation 7. Anxiety 8. Psychotic symptoms: hallucinations, delusions 9. Lack of insight: most people have complete insight

Somatic symptom group: 1. Sleep disorders: difficulty falling asleep, waking up early, sleeping too much 2. Symptoms related to autonomic nervous system disorders: dizziness, headache, palpitation, palpitations, sweating, abnormal skin sensation, digestive tract Abnormal secretion and peristalsis 3. Eating disorders: decreased appetite, reduced physical fitness 4. Decreased energy: listlessness, fatigue, laziness 5. Sexual dysfunction

Depressive disorder: The main clinical feature is significant and persistent low mood. The clinical manifestations can range from depression to grief, and most of them have a tendency to relapse.

Dysthymia: 1. Mild depression characterized by persistent low mood, neither the severity nor the duration of an episode meets the criteria for mild or moderate recurrent depressive disorder 2. The course of the disease lasts for more than 2 years , the intermediate remission time does not exceed 2 months

Mixed depressive and anxiety disorder: 1. Anxiety and depressive symptoms last for several days but less than 2 weeks. 2. The severity and/or duration of any group of symptoms separately are not sufficient to qualify for the corresponding diagnosis.

1. Core symptoms and additional symptoms 2. Duration of disease: lasting ≥2w--- (1) Mild depression: 2 cores + 2 additions (2) Moderate depression: 2 cores + 2 additions The patient has difficulty working, socializing or doing housework (3) Severe depression: 3 cores and 4 with some symptoms reaching severe levels

1. Schizophrenia: Differentiation from depressive episode or depressive stupor accompanied by psychotic symptoms (1) Primary symptoms: ① Depressive disorder has low mood as the primary symptom ② Psychotic symptoms are secondary (2) Coordination Sexuality: ① The mental activities such as thinking, emotion and volitional behavior of patients with depressive disorder are coordinated ② The mental activities of patients with schizophrenia are uncoordinated Most of the symptoms are progressive or continuously progressive, and there are often residual mental symptoms or personality changes during the remission period.

2. Bipolar disorder: (1) Disease characteristics: ① Depressive disorder is a comprehensive suppression of an individual’s emotion, cognition, and volitional behavior ② Bipolar disorder is emotional instability and conversion (2) The age of first onset is early ( 25 years old or earlier), family history of bipolar disorder, accompanied by psychotic symptoms, sudden or more than 5 depressive episodes, unstable mood, irritability or agitation, sleep and weight gain and other clinical characteristics should be highly concerned. Possibility of manic episode

3. Anxiety disorder: (1) Symptom characteristics: ① Depressive disorder is "low mood" ② Anxiety disorder is "fear, fear, worry" (2) ① The emotional expression of patients with anxiety disorder is mainly anxiety and vulnerability, and there are obvious Autonomic nervous system dysfunction and motor restlessness, generally good insight, and eager to seek treatment. There are often mental factors that cause excessive nervous system activity before the disease. ② Depressive disorder is characterized by low mood as the main clinical phase. The patient does not feel good about himself and feels that Pain, boredom, fatigue, and patients with severe somatization symptoms may also be accompanied by symptoms of hypochondriasis

4. Post-traumatic stress disorder: (1) There is a serious, catastrophic, life-threatening traumatic event before the onset of post-traumatic stress disorder, and the intrusive memory of the traumatic event appears repeatedly in consciousness or Characteristic symptoms in dreams, as well as anxiety or emotional numbness, avoidance of people and things related to trauma, etc. are the main clinical manifestations (2) There may be depressive symptoms of varying severity, but they are not the main clinical symptoms, and there is no severe morning or night light symptoms. Rhythm changes (3) Sleep disorders are mostly difficulty falling asleep, trauma-related nightmares and nightmares are common, which are different from depressive episodes characterized by early awakening.

5. Mental disorders caused by physical diseases: Four relationships between depression and physical diseases ① Physical diseases are the direct cause of depressive disorders, that is, they are the biological causes of depressive disorders ② Physical diseases are the causes of depressive disorders, psychology Factors exist: ③ Physical disease and depressive disorder co-occur, there is no direct causal relationship, but they promote each other ④ Depressive disorder is the direct cause of physical disease, such as the physical symptoms associated with depression

Treatment principles: 1. Treatment of the entire course of the disease: ① Treatment in the acute phase: focusing on controlling symptoms and trying to achieve clinical recovery ② Treatment in the consolidation phase: focusing on preventing relapse of the disease ③ Treatment in the maintenance phase: reducing the relapse/recurrence rate, which is generally considered to be at least 2-3 years 2. Individualized and rational medication use 3. Quantitative assessment 4. Combined medication: generally not recommended 5. Establish a therapeutic alliance

Drug treatment: 1. Traditional antidepressants: imipramine, clomipramine, clomipramine, amitriptyline (also used for intestinal stress) --- Adverse reactions: cardiovascular adverse reactions 2. New antidepressants Drugs: serotonin reuptake inhibitors (SSRIs--fluoxetine, paroxetine, citalophan, sertraline), SNRIs, NaSSAs, NDRIs, SARIs---adverse reactions: (1) Gastrointestinal The most common adverse reactions (2) 5-HT syndrome: severe cases include rhabdomyolysis and elevated creatine kinase

Physical therapy: 1. If the patient has suicidal tendencies - electroconvulsive therapy 2. Repetitive transcranial magnetic stimulation therapy 3. Vagus nerve stimulation 4. Deep brain stimulation