The causes of depression are often unclear and may be closely related to multiple factors such as biological, social, and psychological aspects. From a biological perspective, genetics is a primary factor, especially as indicated by family studies, which have found genetics to play a significant role. Genetic factors typically involve multiple gene loci. Furthermore, neurochemical factors like serotonin and norepinephrine are notably related. Beyond biological factors, psychological elements, particularly in individuals with certain depressive traits or personality characteristics, significantly increase the incidence of developing the condition. Social environmental factors are primarily associated with adverse major life events. After experiencing acute life events, individuals may become susceptible to depressive episodes. Hence, it is observed that depression in patients results from multifactorial influences rather than a single factor, culminating from a complex interplay of these elements.