Depression can also develop due to a physical illness, a reaction to a medication that you are taking, or as an outcome of substance abuse.
If a child grows up in a pessimistic environment, in which discouragement is common and encouragement is rare, that child will develop a vulnerability to depression as well.
Person with a close relative who also suffer from depression, can prone to depression. These are the genetic factors. For eg.- if one identical twin suffers from depression or manic-depressive disorder, the other twin has a 70% chance of also having the illness.
Stress or breakup of important attachments, also may precipitate depression, especially in vulnerable persons.
People who have low self-esteem, who consistently view themselves and the world with pessimism, or who are overwhelmed by stress are more prone to depression.
A serious loss, chronic illness, relationship problems, work stress, family crisis, financial setback, or any unwelcome life change can trigger a depressive episode.