The depressive disorders are characterized primarily by mood disturbance (sad, empty, or irritable mood). Individuals with depressive disorders often experience significant somatic changes, such as disruptions in sleep (insomnia or hypersomnia), eating (overeating or loss of appetite), or energy level. Changes in cognition, such as difficulty concentrating, indecisiveness, and morbid ideation (such as thoughts of death) are also common.
Individuals with major depressive disorder experience pervasive sadness or anhedonia (loss of interest) along with significant changes in somatic and/or cognitive functioning. To be diagnosed, these problems must be present nearly every day for at least two weeks. Individuals with persistent depressive disorder (dysthymia) experience similar symptoms, including sad mood and problems with somatic and/or cognitive functioning that occur most days for at least two years. Individuals with premenstrual dysphoric disorder experience marked changes in mood and interpersonal functioning that begin sometime following ovulation and remit within a few days of the onset of menses. Disruptive mood dysregulation disorder is diagnosed in children under 12 years old who experience persistent irritability and extreme behavioral dyscontrol.