It is an invisible killer lurking in the corner, silently devouring the emotions of the world. It, a heavy cold from the mind, recklessly deprive you of the vitality of the past. It is like a dementor, happiness disappears instantly, and despair sweeps in. It is known as the “Blue Lagoon” – depression! So, why do you suffer from depression? Genetic factors. Depression is genetically linked and the offspring of patients have an increased chance of developing the disease. However, this does not mean that only parents who suffer from depression will suffer from the disease themselves, or that they will definitely pass it on to their offspring. Neurobiological factors. Depressed patients have abnormal metabolism of certain neurotransmitters in the brain, such as reduced concentrations of 5-hydroxytryptamine and norepinephrine, resulting in a general state of depressed mental activity and mental functioning. Psychosocial factors. Depression is associated with life stressful events (sudden misfortunes in life, such as unemployment, serious illness) as well as one’s own personality, and life stressful events may become depression triggering factors.