Depression is fundamentally different from general “unhappiness”. It has three main symptoms: depressed mood, slowed thinking and reduced speech and behavior. Depressed mood means not being happy, always distressed and sad, and not interested in anything. They often complain that life is painful, life is like a year, and life is worse than death. Typically, it is severe in the morning and less severe at night. It can range from a mild state of mind to sadness, pessimism, and despair. The patient feels heavy, life is meaningless, depressed, life is like a year, painful, and can’t help themselves. Delayed thinking means that the patient feels that his or her mind is not working well, that he or she cannot remember things, and that he or she has difficulty thinking about problems. Patients feel that their brains are empty, dumb, unresponsive, their brains are not turning, and they feel that they are struggling to think about problems. Reduced verbal behavior means that the patient is not active, does not talk to people, feels lazy, walks slowly, does not want to participate in the outside world and activities that are usually of interest, and lives a lazy life. It is not common for patients to have these typical symptoms. Many patients have only one or two of these symptoms, and the severity varies from person to person. Depressed mood, anxiety, loss of interest, low energy, pessimism, and low self-esteem are all common symptoms of depression and are sometimes difficult to distinguish from a general, short-lived bad mood. Loss of interest is one of the common symptoms in depressed patients. Loss of enthusiasm and enjoyment of life and work in the past, and loss of interest in everything. The patient does not experience the joy of family, does not care about past hobbies, often lives alone behind closed doors, is distant from family and friends, and avoids social interaction. Patients often complain of “no more feelings”, “numbness of emotions”, “no more happiness”. Patients often complain of “no feelings”, “emotional numbness”, “no joy”, “loss of energy, fatigue and weakness, difficulty in washing and dressing, etc., and inability to cope with the little things in life. Patients often describe their condition as a “nervous breakdown” or a “deflated ball”. Low self-evaluation: Patients tend to over-evaluate their own abilities, and look at their present, past and future in a critical, negative and negative manner, describing themselves as useless and with a dark future. Strong feelings of self-blame, guilt, uselessness, worthlessness, helplessness, and in severe cases, self-culpability and suspicion. Patients show a significant, persistent, and generalized depressive state with difficulty in concentration, memory loss, mental retardation, closed-mindedness, and slowness of action, but some patients show restlessness, anxiety, nervousness, and agitation. They are very painful, pessimistic and desperate, feeling that life is a burden and not worth staying, seeking relief by death, and may have strong suicidal thoughts and behaviors. In addition to emotional symptoms, depression can also present some physical symptoms, including sleep disturbance (difficulty in falling asleep, shallow sleep, early awakening, and another situation:, others think he slept well, but I did not sleep at all; typical sleep disorder is waking up, 2 to 3 hours earlier than usual, after waking up, do not return to sleep, and fall into a sad atmosphere), weakness or loss of energy, loss of appetite (most patients have loss of appetite, poor appetite symptoms, delicious food is no longer tempting, the patient does not think of tea or food or tasteless), reduced sexual function (early in the disease can be reduced sexual desire, men may appear impotent, female patients have sensual loss, women will be amenorrhea during the onset of depression), weight loss, constipation, general pain and discomfort and other non-specific physical symptoms. Depressed patients are prone to suicidal thoughts in severe cases due to depressed mood, pessimism and anxiety. Moreover, the success rate of committing suicide is higher because the patient’s thinking and logic are basically normal. Suicide is one of the most dangerous symptoms of depression. According to research, the suicide rate of depressed patients is 20 times higher than that of the general population. More than half of the socially suicidal population may be depressed. Some unexplained suicides may have suffered from severe depression during their lifetime, only to be undetected in time. Since suicide occurs when the disease has progressed to a certain level of severity, early detection of the disease and early treatment are very important for people with depression. Do not wait until the patient has already committed suicide to think that he may be suffering from depression. Patients often have thoughts and acts of death in order to end the pain, suffering and confusion. Depressive episodes can also be characterized by hallucinations, depersonalization, dissociation of reality, obsessions, and terror. Depressive pseudo-dementia can occur due to significant slowing of thought associations and memory loss, which can easily affect the cognitive function of elderly patients