The causes of depression are not yet clear, and it may be closely related to multiple factors such as biological, psychological, and social factors.

Firstly, from a biological perspective, depression may involve genetics, biochemical factors, and endocrine factors, especially closely related to the secretion of serotonin and norepinephrine.

Secondly, psychological factors. The psychological characteristics and personality traits of patients, especially before the onset of depression, are closely related. Particularly, individuals with a depressive disposition are often more likely to develop depression.

Thirdly, social environmental factors. Particularly, encountering major negative life events is often an important contributing factor to clinical depressive episodes.

Therefore, the onset of depression is not caused by a single factor, but likely the result of multifactorial interactions, ultimately leading to the disease onset.