About this profound disease, which can sometimes pretend to be noble, and which may not be seen as a symptom by outsiders, why in the end is it depressed? Genetic factors: certain genes may be associated with depression, depression sometimes presents a family aggregation of episodes, siblings and children of depressed people are also prone to depression. Environmental factors: the stimulation of some major events, such as: unemployment, death of a loved one, divorce, retirement, etc. Social factors: such as social isolation, abuse, whether physical, sexual or psychological. Biological susceptibility: Certain personalities (e.g., withdrawn, paranoid) may be susceptible to depression. Other factors: such as alcoholism and certain substance abuse. What are the possible mechanisms of depression? 1, neurotransmitter dysfunction monoamine neurotransmitter hypothesis is currently more mainstream in the study of depression mechanism (neurotransmitters in the signaling between nerve cells to act as a “messenger” of specific chemicals) monoamine transmitters mainly include 5-hydroxytryptamine (5-HT), norepinephrine (NE) and dopamine (DA). Monoamine transmitters are dysfunctional. For example, a decrease in 5-HT concentration can lead to an increase in negative emotions and a decrease in positive emotions, and may also be associated with symptoms such as loss of appetite, insomnia, and anxiety. 2, brain regions and neural circuit abnormalities Prefrontal cortex, hippocampus, amygdala and other brain regions, closely related to emotions, these regions if abnormal such as atrophy, abnormal activity will also affect mood. 3, neuroendocrine function changes such as hypothalamus-pituitary-adrenal axis, glucocorticoid secretion rhythm disorders can also appear some depressive symptoms.