A mood disorder is the term given for a group of diagnoses in the DSM IV TR classification system where a disturbance in the person's emotional mood is hypothesised 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, whereas the former 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 commonly called Major depression, and Bipolar disorder, formerly known as "manic depression" and described by intermittent periods of manic and depressed episodes.

Classification

Depressive disorders

• Major depressive disorder, commonly called Major depression or unipolar 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".³ Diagnosticians recognize several subtypes or course specifiers:

• Atypical depression is characterized by mood reactivity (paradoxical anhedonia) and positivity, significant weight gain or increased appetite ("comfort eating"), excessive sleep or somnolence (hypersomnia), an sensation of heaviness in limbs known as leaden paralysis, and significant social impairment as a consequence of hypersensitivity to perceived interpersonal rejection.⁴ Difficulties in measuring this subtype have led to questions of its validity and prevalence.⁵

• 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.⁶

• 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).⁷

• 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.⁸

• Postpartum depression 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.⁹

• Seasonal affective disorder 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.¹⁰

• Dysthymia, which is a chronic, milder 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).¹¹

• 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.¹² People with clinical depression can develop RBD, and vice versa, and both illnesses have similar risks.¹³

• 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.¹⁴

Bipolar disorders

• Bipolar disorder, 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 with or without major depressive episodes. For a diagnosis according to the DSM-IV-TR, there requires one or more manic or mixed episodes. A depressive episode is not required for the diagnosis of Bipolar I disorder but it frequently occurs.
• Bipolar II consisting of recurrent intermittent hypomanic and depressive episodes.
• Cyclothymia is a milder form of bipolar disorder, consisting of recurrent hypomanic and dysthymic episodes, without any more severe ones occurring.

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."¹⁵ The relationship between depression and creativity appears to be especially strong among female poets.¹⁶¹⁷

References

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