ORGANUM
The primary feature of major depressive disorder (MDD) is the occurrence of at least one episode of major depression, which is significant depressive symptoms that last for a significant time. It is diagnosed when an individual has persistently low or depressed mood, anhedonia/decreased interest in pleasurable activities, feelings of guilt or worthlessness, lack of energy, poor concentration, appetite changes, psychomotor retardation or agitation, sleep disturbances, or suicidal thoughts.
According to the DSM-5, a patient must have five of the above-mentioned symptoms, of which one must be a depressed mood or anhedonia causing social or occupational impairment, to be diagnosed. History of a manic or hypomanic episode must be ruled out to make a diagnosis of MDD.
There are different types of major depressive disorder:
With psychotic features
With melancholic features
With anxious distress
With atypical features
With mood-congruent psychotic features
With mood-incongruent psychotic features
With catatonia
With peripartum onset
With seasonal pattern
The primary feature of major depressive disorder (MDD) is the occurrence of at least one episode of major depression, which is significant depressive symptoms that last for a significant time. It is diagnosed when an individual has persistently low or depressed mood, anhedonia/decreased interest in pleasurable activities, feelings of guilt or worthlessness, lack of energy, poor concentration, appetite changes, psychomotor retardation or agitation, sleep disturbances, or suicidal thoughts.
With Psychotic features (mood congruent and mood-incongruent)
MDD with psychotic features reflects severe disease and is a poor prognostic indicator. There is a classification of psychotic symptoms as:
Mood-congruent; in harmony with the mood disorder - 'I deserve punishment because I am so bad'
Mood-incongruent; not in harmony with the mood disorder
Patients with mood-incongruent psychotic symptoms may be more likely to have a comorbid primary psychotic disorder such as schizoaffective disorder or schizophrenia.
With Melancholic features
Melancholia (one of the oldest terms in psychiatry - dating back to Hippocrates) is used to describe the dark mood of depression. In modern psychiatry, it is used to describe depression characterised by severe anhedonia, weight loss and profound feelings of guilt; often over trivial events. It is common for these patients to have suicidal ideation. Melancholia is associated with autonomic nervous system changes and endocrine function; thus melancholia is referred to as an endogenous depression, or depression that arises in the absence of external life stressors or precipitants.
With atypical features
As discussed earlier, atypical features are also known as reversed neurovegetative symptoms. They may overeat or oversleep. Patients with atypical features tend to have a younger age of onset and more severe psychomotor slowing. They are also more likely to have comorbid disorders such as anxiety disorders, substance use disorder, or somatic symptoms disorder. They are easy to misdiagnose as anxiety disorder rather than a mood disorder. Patients with atypical features may also have a long-term course, a diagnosis of bipolar I disorder, or a seasonal pattern to their disorder.
Atypical depression and bipolar depression (especially if bipolar type II) seem to be closely associated - many studies have found atypical depression as a common part of bipolar disorder with some reporting it to be the case in two-thirds of the cases. Some studies did include soft bipolarity, such as antidepressant induced hypomania, as episodes of hypomania, which leads to the question of true 'hypomania/mania' in atypical depression. Atypical depression with an onset of younger than age 20 has been found to be more likely associated with bipolar disorder.
A 15-year old adolescent was referred to a sleep center to rule out narcolepsy. His PCx was fatigue, boredom and a need to sleep all the time. He had been failing most of his courses in the 6 months before referral. During psychiatric interview, he denied being depressed but admitted that he had lost interest in everything except his dog, participated in no activities, and had gained ~15kg in 6 months. He believed he was brain damaged and wondered if it was worth living, and the question of suicide disturbed him as it was contrary to his religious beliefs. This psychiatric evaluation led to the prescription of an antidepressant. Although it was successful at reversal of depressive symptoms, it also pushed him to the brink of a manic episode.
With Catatonic features
As a symptom, catatonia can be present in several mental disorders, most commonly schizophrenia and mood disorders. The hallmark symptom of catatonia are stupor, blunted affected, extreme withdrawal, negativism, and marked psychomotor retardation. The presence of catatonic features in patients with mood disorder may have prognostic and treatment significance.
With Seasonal onset
Patients with a seasonal pattern to their mood disorder tend to experience depressive epiosdes during a particular season. most commonly winter. The pattern has become known as seasonal affective disorders (SAD), although DSM-5 does not use this term. There is some controversy regarding whether this represents a subtype of major depressive disorder or a distinct entity. Either way, the presence of the disorder has implications for treatment, as patients with a seasonal pattern to their depression may preferentially respond to light therapy.