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A mood disorder is the term given for a group of diagnoses in the Diagnostic and Statistical Manual of Mental Disorders (DSM IV TR) classification system where a disturbance in the person's mood is hypothesized to be the main underlying feature.^[1] The classification is known as mood (affective) disorders in ICD 10.

English psychiatrist Henry Maudsley proposed an overarching category of affective disorder.^[2] The term was then replaced by mood disorder, as the latter term refers to the underlying or longitudinal emotional state,^[3] whereas the former refers to the external expression observed by others.^[1]

Two groups of mood disorders are broadly recognized; the division is based on whether the person has ever had a manic or hypomanic episode. Thus, there are depressive disorders, of which the best known and most researched is major depressive disorder (MDD) commonly called clinical depression or major depression, and bipolar disorder (BD), formerly known as "manic depression" and described by intermittent periods of manic and depressed episodes.

Classification

Depressive disorders

• Major depressive disorder (MDD), commonly called major depression, unipolar depression, or clinical depression, where a person has two or more major depressive episodes. Depression without periods of mania is sometimes referred to as unipolar depression because the mood remains at one emotional state or "pole".^[4] Diagnosticians recognize several subtypes or course specifiers:

• Atypical depression (AD) is characterized by mood reactivity (paradoxical anhedonia) and positivity, significant weight gain or increased appetite ("comfort eating"), excessive sleep or somnolence (hypersomnia), a sensation of heaviness in limbs known as leaden paralysis, and significant social impairment as a consequence of hypersensitivity to perceived interpersonal rejection.^[5] Difficulties in measuring this subtype have led to questions of its validity and prevalence.^[6]

• Melancholic depression is characterized by a loss of pleasure (anhedonia) 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.^[7]

• Psychotic major depression (PMD), or simply psychotic depression, is the term for a major depressive episode, particularly of melancholic nature, where the patient experiences psychotic symptoms such as delusions or, less commonly, hallucinations. These are most commonly mood-congruent (content coincident with depressive themes).^[8]

• 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 immobile or exhibits purposeless or even bizarre movements. Catatonic symptoms also occur in schizophrenia, a manic episode, or be due to neuroleptic malignant syndrome.^[9]

• Postpartum depression (PPD) is listed as a course specifier in DSM-IV-TR; it refers to the intense, sustained and sometimes disabling depression experienced by women after giving birth. Postpartum depression, which has incidence rate of 10–15%, typically sets in within three months of labor, and lasts as long as three months.^[10]

• Seasonal affective disorder (SAD), also known as "winter depression" or "winter blues", is a specifier. Some people have a seasonal pattern, with depressive episodes coming on in the autumn or winter, and resolving 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.^[11]

• Dysthymia, which is a chronic, different mood disturbance where 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).^[12]

• Depressive Disorder Not Otherwise Specified (DD-NOS) is designated by the code 311 for depressive disorders that are impairing but do not fit any of the officially specified diagnoses. According to the DSM-IV, DD-NOS encompasses "any depressive disorder that does not meet the criteria for a specific disorder." It includes the research diagnoses of recurrent brief depression, and minor depressive disorder listed below.

• Recurrent brief depression (RBD), distinguished from major depressive disorder primarily by differences in duration. People with RBD have depressive episodes about once per month, with individual episodes lasting less than two weeks and typically less than 2–3 days. Diagnosis of RBD requires that the episodes occur over the span of at least one year and, in female patients, independently of the menstrual cycle.^[13] People with clinical depression can develop RBD, and vice versa, and both illnesses have similar risks.^[14]

• Minor depressive disorder, or simply minor depression, which refers to a depression that does not meet full criteria for major depression but in which at least two symptoms are present for two weeks.^[15]

Bipolar disorders

• Bipolar disorder (BD), a mood disorder formerly known as "manic depression" and described by alternating periods of mania and depression (and in some cases rapid cycling, mixed states, and psychotic symptoms). Subtypes include:

• Bipolar I is distinguished by the presence or history of one or more manic episodes or mixed episodes with or without major depressive episodes. A depressive episode is not required for the diagnosis of Bipolar I disorder, but depressive episodes are often part of the course of the illness.
• Bipolar II consisting of recurrent intermittent hypomanic and depressive episodes.
• Cyclothymia is a different form of bipolar disorder, consisting of recurrent hypomanic and dysthymic episodes, but no full manic episodes or full major depressive episodes.
• Bipolar Disorder Not Otherwise Specified (BD-NOS), sometimes called "sub-threshold" bipolar, indicates that the patient suffers from some symptoms in the bipolar spectrum (e.g. manic and depressive symptoms) but does not fully qualify for any of the three formal bipolar DSM-IV diagnoses mentioned above.

It is estimated that roughly one percent of the adult population suffers from bipolar I, roughly one percent of the adult population suffers from bipolar II or cyclothymia, and somewhere between two and five percent suffer from "sub-threshold" forms of bipolar disorder.

Substance-induced mood disorders

A mood disorder can be classified as substance-induced if its etiology can be traced to the direct physiologic effects of a psychoactive drug or other chemical substance, or if the development of the mood disorder occurred contemporaneously with substance intoxication or withdrawal. Alternately, an individual may have a mood disorder coexisting with a substance abuse disorder. Substance-induced mood disorders can have features of a manic, hypomanic, mixed, or depressive episode. Most substances can induce a variety of mood disorders. For example, stimulants such as amphetamine (Adderall, Dexedrine; "Speed"), methamphetamine (Desoxyn; "Meth", "Crank", "Crystal", etc), and cocaine ("Coke", "Crack", etc) can cause manic, hypomanic, mixed, and depressive episodes.

Alcohol-induced mood disorders

High rates of major depressive disorder occur in heavy drinkers and those with alcoholism. Controversy has previously surrounded whether those who abused alcohol and developed depression were self-medicating their pre-existing depression, but recent research has concluded that, while this may be true in some cases, alcohol misuse directly causes the development of depression in a significant number of heavy drinkers.^{[16][17] [18]} High rates of suicide also occur in those who have alcohol-related problems.^[19] It is usually possible to differentiate between alcohol-related depression and depression which is not related to alcohol intake by taking a careful history of the patient. ^[18][20][21] Depression and other mental health problems associated with alcohol misuse may be due to distortion of brain chemistry, as they tend to improve on their own after a period of abstinence.^[22]

Benzodiazepine-induced mood disorders

Long term use of benzodiazepines which have a similar effect on the brain as alcohol and are also associated with depression.^[23] Major depressive disorder can also develop as a result of chronic use of benzodiazepines or as part of a protracted withdrawal syndrome. Benzodiazepines are a class of medication which are commonly used to treat insomnia, anxiety and muscular spasms. As with alcohol, the effects of benzodiazepine on neurochemistry, such as decreased levels of serotonin and norepinephrine, are believed to be responsible for the increased depression.^{[24][25][26][27]} Major depressive disorder may also occur as part of the benzodiazepine withdrawal syndrome.^[28][29][30] In a long-term follow-up study of patients dependent on benzodiazepines, it was found that 10 people (20%) had taken drug overdoses while on chronic benzodiazepine medication despite only two people ever having had any pre-existing depressive disorder. A year after a gradual withdrawal program, no patients had taken any further overdoses.^[31] Depression resulting from withdrawal from benzodiazepines usually subsides after a few months but in some cases may persist for 6–12 months.^[32][33]

Sociocultural aspects

Kay Redfield Jamison and others have explored the possible links between mood disorders—especially bipolar disorder—and creativity. It has been proposed that a "ruminating personality type may contribute to both [mood disorders] and art."^[34] The relationship between depression and creativity appears to be especially strong among female poets.^[35][36]

See also

• Antidepressant
• Self-medication

References

Notes

Cited texts

• American Psychiatric Association (2000), Diagnostic and statistical manual of mental disorders, Fourth Edition, Text Revision: DSM-IV-TR, Washington, DC: American Psychiatric Publishing, Inc., pp. 943, ISBN 0890420254  
• Parker, Gordon; Dusan Hadzi-Pavlovic, Kerrie Eyers (1996), Melancholia: A disorder of movement and mood: a phenomenological and neurobiological review, Cambridge: Cambridge University Press, ISBN 052147275X  
• Sadock, Benjamin J.; Sadock, Virginia A. (2002), Kaplan and Sadock's Synopsis of Psychiatry: Behavioral Sciences/Clinical Psychiatry (9th ed.), Lippincott Williams & Wilkins, ISBN 0781731836