1.Depression is a syndrome of persistent and significant depressed mood for more than 2 weeks, decreased interest, insomnia, decreased appetite/weight loss, fatigue, decreased energy, low self-esteem, decreased memory/distracted attention/hesitation, suicidal ideation or behavior. However, there is no history of manic episodes. 2.Mild mania or mania refers to more than 4 or 7 days of high mood, excitement, high energy, increased activity, arrogance, exaggeration, talking too much, decreased need for sleep, recklessness, impulsiveness and irritability, excessive spending or making irrational investments, and planning too much. The word mania sounds derogatory in Chinese, as if it means madness. In fact, the word Mania is difficult to translate exactly, and originally means a state of excessive excitement, activity and euphoria. 3, Mania and depression are two completely opposite extremes, two clinical phases, so patients with both conditions are called bipolar disorder. 4.If depressed patients have the experience of (light) manic episodes, they should be diagnosed as bipolar disorder, that is, a disease with alternating episodes of depression and mania. The depressive phase of bipolar disorder is called bipolar depression. In short, the depression with mania is bipolar depression, and the depression without mania is depression. 5, never had a manic episode of depression does not mean that it is not bipolar disorder, especially for young patients, often the symptoms of mania has not yet appeared, and once it appears, should promptly consult a doctor to change the original treatment. 6, bipolar depression and depression (from depression without manic episodes) treatment drugs are different and not a disease, although the performance can be exactly the same, such as are depressed mood and reduced interest. 7, bipolar depression is sometimes different from depression symptoms of depression in some characteristics. For example, bipolar depression is often drowsy and weight gain. Depression is usually insomnia and weight loss. If drowsiness and weight gain are suspected to be bipolar depression. 8, bipolar depression tends to start earlier than depression, and often appears before the age of 25. 9, bipolar depression often starts suddenly, unlike depression which has a developmental process, and bipolar depression often does not have any triggers, while depression often has some life triggers. 10, depressed patients who get excited after taking antidepressants often belong to bipolar depression. True depression taking antidepressants does not excite. 11, seasonal episodes of depression to suspect whether it is bipolar depression. Some patients are depressed in winter and manic in summer. When depressed, they have low self-esteem, pessimism and suicide attempts, and when manic, they are arrogant, blindly invest and spend most of their family fortune. 12, diagnosis of bipolar depression often relies on the doctor to ask the patient’s history of manic episodes, and the patient often does not remember the experience of manic episodes, because mania is often a good feeling, unlike the experience of depression gives a deep impression. 13, bipolar depression treatment can not take antidepressants alone, which can induce manic episodes, need to take one or two mood stabilizers at the same time. 14.The course of antidepressant treatment for bipolar depression is short, generally 3 months or less, unlike depression which needs to be treated for more than 9 months, but the course of application of mood stabilizers is longer for the first episode and needs to be maintained for at least 1 year, otherwise it is extremely easy to relapse. 15, Postpartum depression should be carefully evaluated for bipolar depression. 16, Refractory depression, i.e., depression that is not treated with multiple medications, should also be highly suspected to be bipolar depression.