Major Depressive Disorder
MDD is a combination of symptoms that interfere with a person’s ability to work, sleep, study, eat, and enjoy once-pleasurable activities. Major depression is disabling and prevents a person from functioning normally. An episode of major depression may occur only once in a person’s lifetime, but more often, it recurs throughout a person’s life.
Dysthymia, also called Persistent Depressive Disorder, is characterized by long-term (two years or longer), but less severe, symptoms that may not disable a person but can prevent one from functioning normally or feeling well. People with dysthymia may also experience one or more episodes of major depression during their lifetimes. In fact, up to 25 percent of people who develop unipolar depression have been previously diagnosed with dysthymic disorder. Both dysthymic disorder and major depressive disorder can exist at the same time.
Bipolar disorder, also called manic-depressive illness, is not as common as major depression or dysthymia. Bipolar disorder is characterized by cycling mood changes-from extreme highs (e.g., mania or hypomania) to extreme lows (e.g., bipolar depression).
Postpartum depression, which is diagnosed if a new mother develops a major depressive episode within one month after delivery. It is estimated that 10 to 15 percent of women experience postpartum depression after giving birth.
Seasonal Affective Disorder
Seasonal affective disorder (SAD), which is characterized by the onset of a depressive illness during the winter months, when there is less natural sunlight. The depression generally lifts during spring and summer. SAD may be effectively treated with light therapy, but nearly half of those with SAD do not respond to light therapy alone. Antidepressant medication and psychotherapy can reduce SAD symptoms, either alone or in combination with light therapy.