A person who suffers from MDD must either have a depressed mood or a loss of interest or pleasure in daily activities consistently for at least a 2 week period and five or more of the symptoms described below. The feelings of sadness, emptiness or apathy must reflect a change from the person's usual mood and cause clinically significant distress, disability or impairment in daily functioning, including work, social activities and other areas of functioning.
A depressed mood caused by drugs, alcohol or medications is not considered to be a major depressive disorder. Also, a depressed mood caused by a general medical condition; hypothyroidism, for example, is not considered to be MDD. Major depressive disorder is usually not diagnosed in a person who has a history of manic, hypomanic, or mixed episodes (e.g., a bipolar disorder) or if the depressed mood is better accounted for by several other psychiatric disorders. Also, the diagnosis of major depression is not made if the person is grieving over a significant loss in their lives
MDD is characterized by the presence of the majority of these symptoms:
- Depressed mood most of the day, nearly every day, as indicated by either subjective report (e.g., feeling sad or empty) or observation made by others (e.g., appears tearful). In children and adolescents, this may be characterized as an irritable mood.
- Markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day
- Significant weight loss when not dieting or weight gain (e.g., a change of more than 5% of body weight in a month), or decrease or increase in appetite nearly every day
- Insomnia or hypersomnia nearly every day
- Psychomotor agitation or retardation nearly every day
- Fatigue or loss of energy nearly every day
- Feelings of worthlessness or excessive or inappropriate guilt nearly every day
- Diminished ability to think or concentrate, or indecisiveness, nearly every day
- 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