Clinical depression (also called major-depressive disorder, or unipolar depression when compared to bipolar disorder) is a common mood disorder in psychology and psychiatry, in which a person's enjoyment of life and ability to function socially and in day to day matters is disrupted by intense sadness, melancholia, numbness, or despair.
Clinical depression differs from the common term depression and the everyday expression of \"feeling depressed\".
It is diagnosed medically, and treated by therapy and possibly antidepressant drugs.
There are several subtypes, some of which meet the popular perception of sadness, agitation and disruption of sleeping and eating, and others of which do not disrupt enjoyment of good things but create a highly disruptive cycle of inner paralysis and lethargy.
Clinical depression affects about 7–18% of the population on at least one occasion in their lives, before the age of 40.
On the Threshold of Eternity. In 1890, Vincent van Gogh painted this picture seen by some as symbolizing the despair and hopelessness felt in depression.
Van Gogh himself suffered from depression and committed suicide later that same year.
Although a low mood or state of dejection that does not affect functioning is often colloquially referred to as depression, clinical depression is a clinical diagnosis and may be different from the everyday meaning of \"being depressed\".
Many people identify the feeling of being clinically depressed as \"feeling sad for no reason\", or \"having no motivation to do anything\".
A person suffering from depression may feel tired, sad, irritable, lazy, unmotivated, and apathetic.
Clinical depression is generally acknowledged to be more serious than normal depressed feelings.
It often leads to constant negative thinking and sometimes substance abuse or self-harm.
Extreme depression can culminate in its sufferers attempting or completing suicide.
Without careful assessment, delirium can easily be confused with depression and a number of other psychiatric disorders because many of the signs and symptoms are conditions present in depression, as well as other mental illnesses including dementia and psychosis.
The modern idea of depression appears similar to the much older concept of melancholia.
The name melancholia derives from \"black bile\", one of the \"four humours\" postulated by Galen.
Clinical depression was originally considered to be a chemical imbalance in transmitters in the brain, a theory based on observations made in the 1950s of the effects of reserpine and isoniazid in altering monoamine neurotransmitter levels and affecting depressive symptoms.
Since these suggestions, many other causes for clinical depression have been proposed.