Also known as affective disorders and mood disorders. Previously known as affective psychoses. It is a group of mental disorders with significant and persistent high or low emotions as the main clinical feature, often accompanied by corresponding changes in thinking and behavior. The manifestations of affective disorders vary greatly. Milder ones may be a reaction to some negative life events, while severe ones may become a serious recurrent or even chronic disabling disorder. Severe cases may have psychotic symptoms such as hallucinations and delusions. They often recur, most of which can be relieved, and a few have residual symptoms or become chronic. The first onset age of this type of mental disorder is mostly between 16 and 30 years old. Clinically, it can be divided into four types: depressive episodes, manic episodes, bipolar disorders, and persistent mood disorders.