The patients with depression were observed and followed up to evaluate the changes of symptoms and cognitive function in patients with depression at different time points before and after drug treatment. At the same time, immunometabolism indicators in serum, urine and stool were detected to screen out immunoinflammatory markers related to cognitive function and treatment response in patients with depression, hoping to provide a new strategy for optimal treatment of depression.

1. Participants were included according to the inclusion and exclusion criteria, and demographic data of depressed patients and healthy controls were recorded, including age, sex, ethnicity, occupation, etc. Subjects in the depression group were treated with antidepressants (as recommended by the guidelines) and were followed up baseline, 2 weeks, 8 weeks, 12 weeks, and 24 weeks after treatment, respectively. At each follow-up point, symptoms were assessed using Hamilton Depression Scale (HAMD), Hamilton Anxiety Scale (HAMA), Depression Screening Scale (PHQ-9) and Generalized Anxiety Scale (GAD-7), and cognitive function was assessed using Thinc-it at three follow-up points: baseline, 12 weeks after treatment, and 24 weeks after treatment. General data were compared between patients with depression and healthy controls at baseline.
2. The depression group was followed up. Serum and fecal of patients with depression were collected at 5 follow-up points at baseline, 2 weeks, 8 weeks, 12weeks and 24 weeks after treatment, and serum metabolic indexes and fecal metagenome were detected.

Inclusion Criteria:

• Age 18-60 years old, male or female;
• Meet the diagnostic criteria for depression in the International Classification of Diseases-10 (ICD-10), and the Hamilton Depression Scale (HAMD) score ≥18 points;
• Junior high school education and above, can cooperate with the completion of relevant scales and sample collection;
• did not receive antidepressant therapy at admission or took medication for less than 14 days; And the duration of drug withdrawal ≥3 months;
• No history of infection and taking hormones, antibiotics or anti-inflammatory drugs in the past 1 month;
• History of physical diseases such as centerless, liver, kidney and gastrointestinal tract, active infection, active or chronic inflammation, autoimmune diseases, etc.

Exclusion Criteria:

• Pregnant and lactating women;
• Clinically significant or unstable medical conditions, including congestive heart failure, liver and kidney failure, cancer, immune and metabolic endocrine diseases;
• Patients with acute or chronic infection, taking anti-inflammatory drugs, cortisol hormones, and receiving antibiotics for 3 consecutive days in the past 1 month;
• Patients with neuropsychiatric diseases other than depression.

Meet the diagnostic criteria for depression in the International Classification of Diseases-10 (ICD-10), and the Hamilton Depression Scale (HAMD) score ≥18 points