Melancholic depression, or depression with melancholic features, is a DSM-IV and DSM-5 specifier of depressive disorders. This type of depression has specific symptoms that make it different from the standard clinical depression list of symptoms. Furthermore, melancholic depression has a specific subset of causes and can respond differently to treatment than other clinical depression types.

Classification 
Depression with melancholic features is classified under the fourth and fifth versions Diagnostic and Statistic Manual of Mental Disorders (DSM-IV and DSM-5) as a specifier of depressive disorders. A specifier essentially is a subcategory of a disease, explaining specific features or symptoms that are added to the main diagnosis.

Signs and symptoms
Melancholic depression requires at least one of the following symptoms during the last depressive episode: 
 Anhedonia (the inability to find pleasure in positive things)
 Lack of mood reactivity (i.e. mood does not improve in response to positive/desired events; failure to feel better)
And at least three of the following: 
 Depressed mood that is subjectively different from grief or loss (marked by despair, gloominess, and "empty-mood")
 Severe weight loss or loss of appetite
 Psychomotor agitation or retardation (i.e. increased or decreased movement, speech, and cognitive function)
 Early morning awakening (i.e. waking up at least 2 hours before the normal wake up time of the patient)
 Guilt that is excessive
 Worse depressed mood in the morning
Melancholic features apply to an episode of depression that occurs as part of either major depressive disorder, persistent depressive disorder (dysthymia), or bipolar disorder I or II. They are more likely to occur in patients who suffer from depression with psychotic features. People with melancholic depression also tend to have more physically visible symptoms such as slower movement or speech.

Causes
The causes of melancholic depressive disorder are believed to be mostly biological factors for instance, people may have inherited the disorder from their parents. Biological origins of the condition include problems with the HPA axis and sleep structure of patients. MRI studies have indicated that melancholic depressed patients have issues with the connections between different regions of the brain, specifically the insula and fronto-parietal cortex. Some studies have found that there are biological marker differences between patients with melancholic depression and other subtypes of depression. Sometimes stressful situations can trigger episodes of melancholic depression, though this is a contributing cause rather than a necessary or sufficient cause. Moreover, people with psychotic symptoms are also thought to be more susceptible to this disorder. 

Physicians often do not notice the symptoms in patients of old age because they perceive the symptoms to be a part of dementia. Major depressive disorder, melancholic or otherwise, is a separate condition that can be comorbid, or occurring at the same time as dementia in the elderly.

The research regarding melancholic depression consistently finds that men are more likely to receive a melancholic depression diagnosis.

Treatment
Melancholic depression, due to some fundamental differences with standard clinical depression or other subtypes of depression, has specific types of treatments that work, and the success rates for different treatments can vary. Treatment can involve antidepressants and empirically supported treatments such as cognitive behavioral therapy and interpersonal therapy for depression. 

Melancholic depression is often considered to be a biologically based and particularly severe form of depression. Therefore, the treatments for this specifier of depression are more biomedical and less psychosocial (which would include talk therapy and social support).  The general initial or "ideal" treatment for melancholic depression is antidepressant medication, and psychotherapy is added later on as support if at all. The scientific support for medication as the best treatment is that patients with melancholic depression are less likely to improve with placebos, unlike other depression patients. This indicates the improvements observed after medication actually come from the biological basis of the condition and the treatment. There are several types of antidepressants that can be prescribed including SSRIs, SNRIs, tricyclic antidepressants, and MAOIs; the antidepressants tend to vary on how they work and what specific chemical messengers in the brain they target. SNRIs are generally more effective than SSRIs because they target more than one chemical messenger (serotonin and norepinephrine).

Although psychotherapy treatments can be used such as talk therapy and cognitive behavioral therapy (CBT), they have shown to be less effective than medication. In a randomized clinical trial, which is one of the best types of studies to determine cause and effect relationships, it was shown that CBT was less effective than medication in treating symptoms of melancholic depression after 12 weeks. 

Electroconvulsive therapy (ECT) was previously believed to be an effective treatment for melancholic depression.  ECT has been more commonly used for patients with melancholic depression due to the severity. In 2010, a study found that 60% of depression patients treated with ECT had melancholic symptoms. However, studies since the 2000s have failed to demonstrate positive treatment results from ECT, although studies also indicate a more positive response to ECT in melancholic patients than other depressed patients.

It has been observed in studies that patients with melancholic depression tend to recover less often than other types of depression.

Incidence
The incidence of having the melancholic depression specifier among patients with clinical depression is estimated to be about 25% to 30%.   

The incidence of melancholic depression has been found to increase when the temperature and/or sunlight are low. 
According to the DSM-IV, the "melancholic features" specifier may be applied to the following only: 
Major depressive episode, single episode
Major depressive episode, recurrent episode
Bipolar I disorder, most recent episode depressed
Bipolar II disorder, most recent episode depressed
It is important to note, however, that people who suffer from melancholic depression do not need to have melancholic features in every depressive episode.

See also
Melancholia

References

Mood disorders
Major depressive disorder
Melancholia

fr:Mélancolie
io:Melankolio
zh:忧郁型抑郁障碍