There are two major components in the diagnosis or examination of depression, as follows: 1. Exclusionary examination: depression is caused by brain dysfunction or is a disease of the brain, so firstly, brain-related examinations such as CT, MRI, or even PET-CT, EEG, etc. should be done. Secondly, somatic aspects should be examined, because hypothyroidism and hyperthyroidism can affect mood, so these endocrine diseases should be ruled out. In addition, older patients have hypertension and diabetes, all of these diseases should be examined and ruled out to determine if depression is caused by somatic diseases; 2. Assessment for melancholic mood aspects, such as whether there are hallucinations, delusions, depression, etc., how about the degree of depression, whether it is mild or severe, and whether there are manifestations of mania, because the cause of depression often has mania; 3. Communication between the doctor and the patient Conversation, also called psychiatric examination. During the conversation, we can understand the patient’s depressive state, the severity of depression, and whether there is a suicidal tendency. This examination is also a very important psychological assessment.