This term, imposed by the DSM, actually means “marked depression. Although they are not unanimous, the U.S. criteria of DSM-IV (Diagnostic and Statistical Manual of Mental Disorders ) major depressive disorder are: A person must have at least 5 of the 9 following symptoms for a period at least two weeks, most of the time, resulting in a change in the mode of operation. At least one of these two criteria must be present: sad mood, anhedonia.

• Sad mood (depression): described as more intense than the pain of bereavement. The patient is joyless and oppressed, sometimes it is unable to perceive any sense. Generally the mood is worse in the morning. In children and adolescents, this may manifest as increased irritability.
• Anhedonia: decreased pleasure or interest in all activities, including those that usually give pleasure. Habits are changing hobbies are neglected, everything seems dull and empty, including the activities usually rewarding.
• Change involuntary weight: Increase or decrease of 5% or more of usual weight in a month. Eventually, recent change in appetite
• Sleep disorders: decrease (sleep) or increase (hypersomnia) of sleep time
• Impaired concentration or making decisions
• Behavior Disorders: agitation or retardation (bradyphrenia) reported by the surroundings.
• Asthenia: feeling of fatigue or decreased energy
• Feelings of guilt bloated, unjustified and often related to self-depreciation of the patient.
• Ideas black: will die, active suicidal ideation with or without a specific plan, eventually attempted suicide.