How are mood disorders classified?
First and foremost, there are two main types of mood disorders :
- Unipolar disorders, whereby subjects suffer only depression that is more or less severe;
- Bipolar disorders, whereby subjects alternate between depressive periods and manic periods.
There are subtypes of Bipolar disorders, established according to the nature and severity of the symptoms.
Bipolar I (BPI) or Type I Disorder (according to the DSM IV *) = typical manic episodes (or mixed episodes) and major depressive (per the DSM IV) or sub-depressive episodes. Diagnosis is usually established during a manic episode; BPI Disorder is characterised by one or several manic or mixed episodes (a combination of excitability and depression) and depressive episodes of varying severity (diagnosis can be established even when there is no depressive disorder).
Bipolar II (BPII) or Type II Disorder (according to the DSM IV *) = hypomanic and major depressive episodes. The depressive state is most prominent, however hypomania may be insidious and affect overall functioning. BPII Disorder is defined by the occurrence of one or several hypomanic episodes (a milder form of euphoria) and one or more typical depressive episodes.
Bipolar III (BPIII) = depressive episodes with a family history of manic or depressive episodes and manic states that have been pharmacologically induced (hypomania resulting from some substance or drug). This type of disorder is not listed in any of the standard classification systems (ICD10, DSM IV *). Bipolar Type III disorders are consistent with either unipolar types (recurring depression) with a family history of bipolar disorders, or with types of hypomania or mania induced by antidepressants.
Cyclothymia = On the edge of bipolar disorders (mild form), cyclothymiacs is characterised by fluctuating moods of alternating episodes of hypomania and depression or sub-depressive moods. This disorder can be just as debilitating because it is chronic and goes untreated (this disorder is still mostly unknown). Cyclothymia can develop into Type I and II bipolar disorders.
Please note that bipolar disorders or manic-depressive illness affect about 1.3% of the general population.
Type I (BP I) represents 0,8 %
Type II (BP II) represents 0,5 %
(*) DSM-IV: Diagnostic Statistics Manual – 4th edition
The DSM-IV is a classification tool that represents the current result of about 30 years’ worth of work in the United States to more accurately define mental disorders. It was published by the American Psychiatric Association in 1994. The 4th edition was used as reference for these articles.
The approach adopted by the DSM-IV aims to eliminate interpretation in the establishment of a diagnosis. To this end, accurate diagnostic criteria were defined by the American Psychiatric Association. Four criteria are outlined :
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descriptive characteristics of the targeted symptom
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its rate of occurrence or its duration
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the age of the person at onset
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exclusionary criteria based on the presence of other diagnostics.
A minimum number of symptoms are required for diagnosis. For some diagnoses (e.g. for depression), certain symptoms must be present.
The DSM-IV consists of five axes that examine :
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Axis I : clinical disorders
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Axis II : personality disorders and mental retardation
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Axis III : general medical conditions
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Axis IV : psychosocial and environmental problems
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Axis V : global assessment of functioning scale
Reader information: This article is based on discussions and texts from the Medical Comitee – Last update
: 10/01/2011
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