Depression - Diagnosis

Major depressive episode
A major depressive episode is characterized by the presence of a severely depressed mood that persists for at least two weeks. Episodes may be isolated or recurrent and are categorized as mild (few symptoms in excess of minimum criteria), moderate, or severe (marked impact on social or occupational functioning). An episode with psychotic features&mdash;commonly referred to as psychotic depression&mdash;is automatically rated as severe. If the patient has had an episode of mania or markedly elevated mood, a diagnosis of bipolar disorder is made instead. Depression without mania is sometimes referred to as unipolar because the mood remains at one emotional state or "pole". DSM-IV-TR excludes cases where the symptoms are a result of bereavement, although it is possible for normal bereavement to evolve into a depressive episode if the mood persists and the characteristic features of a major depressive episode develop. The criteria have been criticized because they do not take into account any other aspects of the personal and social context in which depression can occur. In addition, some studies have found little empirical support for the DSM-IV cut-off criteria, indicating they are a diagnostic convention imposed on a continuum of depressive symptoms of varying severity and duration: excluded are a range of related diagnoses, including dysthymia which involves a chronic but milder mood disturbance, Recurrent brief depression which involves briefer depressive episodes, Minor depressive disorder which involves only some of the symptoms of major depression, and Adjustment disorder with depressed mood which involves low mood resulting from a psychological response to an identifiable event or stressor.

Subtypes
The DSM-IV-TR recognizes several subtypes, which are sometimes called "course specifiers":


 * Atypical depression is characterized by mood reactivity (paradoxical anhedonia) and positivity, significant weight gain or increased appetite (comfort eating), excessive sleep or sleepiness (hypersomnia), a sensation of heaviness in limbs known as leaden paralysis, and significant social impairment as a consequence of hypersensitivity to perceived interpersonal rejection.


 * Catatonic depression is a rare and severe form of major depression involving disturbances of motor behavior and other symptoms. Here the person is mute and almost stuporose, and either remains immobile or exhibits purposeless or even bizarre movements. Catatonic symptoms also occur in schizophrenia or in manic episodes, or may be caused by neuroleptic malignant syndrome.


 * Melancholic depression is characterized by a loss of pleasure in most or all activities, a failure of reactivity to pleasurable stimuli, a quality of depressed mood more pronounced than that of grief or loss, a worsening of symptoms in the morning hours, early morning waking, psychomotor retardation, excessive weight loss (not to be confused with anorexia nervosa), or excessive guilt.

Other types of depression, not categorized as Major depressive disorder, are recognized by the DSM-IV-TR:
 * Postpartum depression (Mild mental and behavioral disorders associated with the puerperium, not elsewhere classified in ICD-10 ) refers to the intense, sustained and sometimes disabling depression experienced by women after giving birth. Postpartum depression, which has incidence rate of 10–15% among new mothers, typically sets in within three months of labor, and lasts as long as three months.


 * Seasonal affective disorder is a form of depression in which depressive episodes come on in the autumn or winter, and resolve in spring. The diagnosis is made if at least two episodes have occurred in colder months with none at other times, over a two-year period or longer.

Other ways of categorizing depression have been used historically and they include:
 * Anaclitic depression
 * Dysthymic disorder
 * Endogenous depression
 * Involutional depression
 * Reactive depression
 * Recurrent depression
 * Treatment resistant depression

Differential diagnoses
In order to decide that major depressive disorder is the most likely diagnosis, the probability of several other potential diagnoses must be considered, including the following:


 * Dysthymia is a chronic, milder mood disturbance in which a person reports a low mood almost daily over a span of at least two years. The symptoms are not as severe as those for major depression, although people with dysthymia are vulnerable to secondary episodes of major depression (sometimes referred to as double depression).


 * Adjustment disorder with depressed mood is a mood disturbance appearing as a psychological response to an identifiable event or stressor, in which the resulting emotional or behavioral symptoms are significant but do not meet the criteria for a major depressive episode.


 * Bipolar disorder, previously known as manic-depressive disorder, is a condition in which depressive phases alternate with periods of mania or hypomania. Although depression is currently categorized as a separate disorder, there is ongoing debate because individuals diagnosed with major depression often experience some hypomanic symptoms, indicating a mood disorder continuum.