Depression
This page is reference information compiled from the cited sources. It is not medical advice. For any decision about health, diagnosis or care, consult a qualified professional.
What it is
Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. The term was adopted by the American Psychiatric Association for this symptom cluster under mood disorders in the 1980 version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III). A person facing a major depressive episode may have feelings of hopelessness and self-hatred, and may also experience suicidal ideation and thoughts of self-harm. This can manifest as a complete loss of emotional reactivity, a neurological protection response known as emotional blunting or anhedonia. Major depression significantly affects a person's family and personal relationships, work or school life, sleeping and eating habits, and general health.
Key facts
The disorder causes the second-most years lived with disability, after lower back pain. The diagnosis is based on the person's experiences, and behavior reported by family or friends, and a mental status examination, with no laboratory test for the disorder. The most common time of onset is in a person's 20s, and men are much less likely to report than women. The course of the disorder varies widely, from one episode lasting months to a lifelong disorder with recurrent episodes. Major depressive disorder is believed to be caused by a combination of genetic, environmental, and psychological factors, with about 40% of the risk being genetic. Risk factors include a family history of the condition, major life changes, childhood traumas, environmental lead exposure, certain medications, chronic health problems, and substance use disorders. Other symptoms include poor concentration and memory, withdrawal from social situations, reduced sex drive, irritability, and sleep disturbances like insomnia or hypersomnia. In severe cases, depressed people may have psychotic symptoms such as delusions or hallucinations.
When to seek professional help
The source associates professional care with the diagnosis and treatment of the disorder. Diagnosis is based on reported experiences and behavior, and may involve testing to rule out physical conditions. Those with major depressive disorder are typically treated with psychotherapy and antidepressant medication. Hospitalization may be necessary in cases with associated self-neglect or a significant risk of harm to self or others. The source notes that men are much less likely to report than women, with approximately 33.2% of men and 43.0% of women with depressive symptoms reporting seeking help. Diagnosis may be delayed or missed in children when symptoms are interpreted as normal moodiness, and in elderly people who may not present with classical depressive symptoms.
Source: Major depressive disorder (CC BY-SA 4.0 (Wikipedia)), retrieved 2026-08-27.
