The onset of depression is caused by a variety of factors, such as premorbid personality, adverse life and work events, genetic factors, stress, etc., not a single factor, these factors are the cause, the onset of the cause is still unknown. Depression is also different from the principles of common illnesses in terms of medication: 1. If the dose of the drug taken is not enough, it will make the drug slow to work and less effective. Generally speaking, the usual amount of medication introduced in the manual is the therapeutic amount, but for each patient, a psychiatrist should judge whether the amount is sufficient. 2, the full course of treatment means that the amount of medication taken is enough, the time taken should also be enough, not enough time will not be effective. Generally speaking, the adequate amount of medication taken 8-10 weeks, to assess the efficacy, decide the next step of treatment, continue to take or change the medication or a combination of medication. 3, the principle of individualization means that each patient’s efficacy and side effects of the drug are different, there will be a large difference. It is possible that I take this drug with good efficacy and no side effects, while you take this drug with poor efficacy and high side effects. I will adjust the dosage and duration of medication according to the patient’s specific situation after taking the medication. This is the principle of individualization. 4, long-term drug maintenance treatment is essential because depression is a common, easy to relapse emotional disease, the literature reported that if not given drug intervention, there may be about 10-20% of patients only once in a lifetime, and will not relapse, but most of the patients may relapse. Therefore, long-term medication maintenance is essential to prevent relapse in order to minimize or prevent relapse in every patient. Generally speaking, patients should take medication systematically for more than one year after they have recovered from their first disease, more than three years after they have had the disease twice, and long-term medication for patients who have had the disease three times or more. The duration of this medication is for your reference, but for each patient, the duration of medication should be determined according to the specific situation of the patient.