[The concept of temperament and its contribution to the understanding of the bipolar spectrum].

The present article attempts first to provide a historical overview of the concept of temperament,The present article attempts first to provide a historical overview of the concept of temperament,since its foundation by Polybos (4th century B.C.) and the school of Cos, its predominant role in theshaping of the anthropological and humanitarian sciences, until the modern theoretical formulations,such as those proposed by Robert Cloninger and Hagop Akiskal. Secondly, recent literature ispresented, which suggests a strong link of different temperament structures to mental health andpsychopathology. Hans Eysenck (1916-1997) was the first psychologist to establish approaches topersonality differences and to distinguish three dimensions of personality: Neuroticism, Extraversionand Psychotisism. Eysenck was followed by McCrae and Costa who proposed that there are five basicdimensions of personality ("Big Five"). In the mid-1980s, Robert Cloninger developed a distinctivedimensional model of temperament and character traits. Hagop Akiskal emphasized on the affectivecomponents of temperament and their possible connections to mood disorders and creativity.Specifically, temperament assessment seems to help in differentiating between the relationship ofvarious temperaments and the clinical manifestations of bipolar illness. Within the area of mood disorders,specific affective temperaments might constitute vulnerability factors, as well as clinical pictureand illness course modifiers. Viewing mood disorders under this prism gives birth to the concept ofthe bipolar spectrum with major implications for all aspects of mental health research and providingof care. The hyperthymic and the depressive temperaments are related to the more 'classic' bipolarpicture (that is euphoria, grandiose and paranoid thinking, antisocial behavior, psychomotor accelerationand reduced sleep and depressive episodes respectively). On the contrary cyclothymic, anxiousand irritable temperaments are related to more complex pictures and might predict poor responseto treatment, violent or suicidal behavior and high comorbidity. Unipolar disorder diagnosis is oftenchanged due to the fact that a manic or mixed episode can occur after several years of treatment failure.In these cases the evaluation of temperament can prove to be effective in distinguishing betweenunipolar and bipolar depression and thus favoring treatment planning. In addition, temperament assessmentchanges the definition of bipolarity by supporting the concept of "bipolar spectrum". This isa factor that can lead to a rise in prevalence of bipolar cases. Furthermore, the evaluation of temperamenthas shifted our understanding of bipolarity towards the concept of the 'bipolar spectrum'. It hasalso led to an increase in the prevalence of bipolar disorder cases, notably bipolar II, and a decrease in unipolar cases. Finally, incorporating the concept of temperament in our understanding of bipolardisorder constitutes a challenging issue, which can lead to better treatment and outcome of patients.