Major depressive episode can be defined by the criteria listed below. At least five of the symptoms, including one or the other of the first two, must be present during the same two-week period for major depression to be diagnosed.
- Depressed mood (or can be irritable mood in children and adolescents) most of the day, nearly every day, as indicated either by the subjective account or observation by others.
- Markedly diminished interest or pleasure in all day, or almost all, activities most of the day, nearly every day (as indicated either by subjective account or observation by others of apathy most of the time)
- Significant weight loss or weight gain when no dieting (e.g. more than 5% of body weight in a month), or decrease or increase in appetite nearly every day (in children, consider failure to make expected weight gains).
- Insomnia or hypersomnia nearly every day
- Psychomotor agitation or retardation nearly every day (observation by others, not merely subjective feelings of restlessness or being showed down)
- Fatigue or loss of energy nearly every day
- Feelings of worthlessness or excessive of inappropriate guilt which may be delusional nearly every day (not merely self reproach or guilt about being sick)
- Diminished ability to think or concentrate, or indecisiveness, nearly every day (either by subjective account or as observed by others)
- Recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide
