Three of the most prevalent types of depressive disorders are major depression , dysthymia , and bipolar disorder . Major depression involves a combination of symptoms that interfere with the ability to work, sleep, eat and enjoy pleasurable activities. These disabling episodes can occur once, twice, or several times in a lifetime. People with dysthymia may also have bouts of major depression. Bipolar disorder , formerly called manic-depressive illness, is not nearly as prevalent a form of depression.
Bipolar disorder involves cycles of depression and elation or mania.
Sometimes the mood switches are rapid, but most often they are gradual. Some types of depression run in families. Psychological makeup also plays a role in vulnerability to depression. People with low self-esteem, who consistently view themselves and the world with pessimism, or who are readily overwhelmed by stress are prone to depression. Depressive episodes may also be triggered by a serious loss, chronic illness, difficult relationship, financial problem or any unwelcome change in life patterns.