There are basically three distinct types of depression. One category includes people who always feel a little depressed and pessimistic, say they’ve felt that way for years, and tend to have low self-esteem. This depression reflects learned attitudes and responds to psychotherapy, not to drugs. The second type involves a serious loss, such as the death of someone close or development of a critical illness. This is a form of grief, and will get better with time. The third kind is an illness that tends to run in families and has vegetative symptoms. It usually lasts for about a year, but recurs many times in the person’s life. This depression requires treatment with antidepressant drugs.
Read the entire article here: Diagnosing Depression