Unipolar mania is a form of bipolar disorder whereby individuals only experience manic episodes without depression. Depression is often characterised by a persistent low mood, decreased energy and thoughts of suicide. What is seen as its counterpart, mania, can be characterized by racing thoughts, less need for sleep and psychomotor agitation.
The concept of bipolar disorder was initially introduced by Baillarger, Falret and Grinsinger in the 19th century. However, German psychiatrist Emil Kraepelin was the first to discover the category of manic depressive disorder, and this eventually led to the appearance of bipolar disorder in the third edition of the Diagnostic and Statistical Manual (DSM-3). It was also Kraeplin who first used the term of "periodic mania" in 1889, to refer to people with recurrent manic episodes and no depression. The following year, Carl Wernicke proposed that mania and depression should be viewed as separate disorders. Some years later in 1979, the two forms were individualised in the literature.
Further research led to the suggestion that there is a distinction between unipolar mania and manic-depressive psychosis and that this may have a genetic basis. However this has not yet been tested. Research on unipolar mania has continued to evolve but has not been acknowledged in the most recent DSM (DSM-5). As the time went on, unipolar mania has become an invalid diagnosis due to its variations across different patients. Currently patients with symptoms of mania, even in the absence of any depressive symptoms, would get the bipolar I diagnosis.
Clinical features
Despite the lack of acknowledgment of unipolar mania as a separate disorder, studies have found significant differences between the clinical features of unipolar mania and bipolar disorder.
Individuals with unipolar mania are less likely to experience:
Depressive features
Diurnal variation of mood
Hallucination
Comorbid anxiety disorders and anxiety symptoms
Suicidal ideas or attempts
Hostility
Rapid Cycling and Cyclothymia (both common features in Bipolar Disorder)
However are more likely to:
Experience delusions
Exhibit formal thought disorder
Have abused drugs in the past, in particular marijuana and amphetamines
Have hyperthymia
The episodes experienced by individuals with unipolar mania, generally have a stronger tendency to present with psychosis or/and need psychiatric assistance. Psychotic features tend to also be higher at both the start and throughout the course of unipolar mania.
Prevalence and diagnosis criteria
Generally, there are two aspects which are taken into consideration when unipolar mania is being defined. This includes the length of the illness and how many manic episodes the individual has. Currently, there is a lack of clarity over how prevalent this disorder is and the number of individuals who have been diagnosed with bipolar disorder, despite not experiencing depressive periods. This is due to the fact that in studies of unipolar mania, researchers have differed in their definitions and diagnosis criteria's. The prevalence of this disorder has a large range from as low as 1.1% of bipolar disorder cases, to 65.3%
It was Carlo Perris' definition in 1966, which was most commonly used in studies on this topic during the 1970s and early 1980s. He defined unipolar mania to be present, when an individual has a minimum of one manic episode without experiencing any depressive episodes. The prevalence of this disorder when based upon this definition, was up to 35.2% of all bipolar inpatients.
Other definitions of unipolar mania in research include, at least three manic episodes without the experience of a depressive period for the length of the study. In this study 56.6% of the sample of 173 patients experienced only manic episodes. Another study defined this disorder as a minimum of one hospitalisation for a manic episode but no hospitalisation or sematic treatment for depression. Using this definition, it was found that 15.7% of individuals diagnosed with Bipolar 1 in fact have unipolar mania. In a research study which used the diagnosis criteria of having 3 manic episodes without any depressive episodes, unipolar mania was prevalent in 40% of the bipolar inpatients.