61 情感性疾患重鬱發作（major depressive episode）依照美國精神醫學會精神疾病診斷及統計手冊第四版規定，其症狀發作之間期（duration）必須至少幾週？

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Major depressive episode

Main article: Major depressive episode

A major depressive episode is characterized by the presence of a severely depressed mood that persists for at least two weeks.^[3] Episodes may be isolated or recurrent and are categorized as mild (few symptoms in excess of minimum criteria), moderate, or severe (marked impact on social or occupational functioning). An episode with psychotic features—commonly referred to as psychotic depression—is automatically rated as severe. If the patient has had an episode of mania or markedly elevated mood, a diagnosis of bipolar disorder is made instead.^[111] Depression without mania is sometimes referred to asunipolar because the mood remains at one emotional state or "pole".