What are the different forms of depression?

There are several forms of depressive disorders. The most common are major depressive disorder and dysthymic disorder.

Major depressive disorder, also called major depression, is characterized by 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.

Dysthymic disorder, also called dysthymia, 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.

Some forms of depressive disorder exhibit slightly different characteristics than those described above, or they may develop under unique circumstances. However, not all scientists agree on how to characterize and define these forms of depression. They include:

Psychotic depression, which occurs when a severe depressive illness is accompanied by some form of psychosis, such as a break with reality, hallucinations, and delusions.

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.

1. 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.

2. 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） to extreme lows （e.g., depression）. Visit the NIMH website for more information about bipolar disorder.

抑郁症有几种类型。最常见的是重度抑郁症和心境恶劣障碍。

重度抑郁症，也叫做重度抑郁，以一组妨碍个体的工作、睡眠、学习、饮食和享乐（一度愉悦的活动）的症状为特色的疾病。重度抑郁能致残并使个人正常机能受损。重度抑郁发作可能在个体一生中仅出现一次，但是更多的情况是重度抑郁在一生中反复发作。

心境恶劣障碍，也叫做恶劣心境，以长期（两年或更长）但是较轻的症状为特色。它并不一定使个人致残，但是能使个人正常机能受损或不能感到心情舒服。心境恶劣患者在其一生中，也会经历一次或更多此的重度抑郁。

一些抑郁症形式在表现上与上述障碍相比，稍有不同的特征；或者，它们可能在特定的环境下患上。但是，并不是所有科学家都同意如何对这些形式的抑郁症的定义和分类。它们包括：

精神病性抑郁症，这种疾病会出现，当重度抑郁症伴随有一些精神病形式，比如丧失现实感、幻觉和妄想。

产后抑郁症，如果新生儿母亲在分娩一个月后重度抑郁症发作，那么该病便确诊了。我们估计10-15%的女性在生产后，经历重度抑郁症。

季节性情绪紊乱症（SAD）,以冬季缺乏自然光，抑郁症发作为特色的。抑郁通常在春季和夏季消褪。SAD患者可能对光线疗法有效，但是几乎一半的SAD患者对单用光线疗法无反应。抗抑郁药物和心理疗法可以减少SAD症状。它们要么单独使用，或者与光线疗法联用。

双相情感障碍，也叫做躁郁症，并不像重度抑郁症或心境恶劣一样普遍。双相情感障碍是以环性心境变化--从高峰（比如，躁狂）到低谷（比如，抑郁）为特色的。请参看NIMH网站获得更多关于双相情感障碍的信息。