La CIM-10 (classification internationale des maladies, dixième révision), dans son chapitre sur les troubles mentaux, vise à être utilisée dans des contextes culturels divers. Dans une perspective historique, elle permet également de mieux comprendre le destin d'individus dont le comportement et les trajectoires de vie ne pouvaient qu'imparfaitement être appréhendés jusque-là. La vie et le caractère de Mozart ont généré nombre d'hypothèses parfois fantaisistes nourries par une absence d'éléments scientifiques suffisants. L'étude des correspondances de Mozart ainsi que de sa biographie nous amène à reconnaître chez lui des épisodes dépressifs parfois sévères correspondant aux critères de la CIM-10. En revanche, les arguments avancés par d'autres en faveur d'épisodes maniaques ou hypomaniaques ne sont étayés par aucune preuve historique suffisante. Ses variations d'humeur importantes et ses comportements parfois impulsifs relèvent plutôt d'un trouble de la personnalité caractérisé par des symptômes de personnalité dépendante, mais également par des symptômes de personnalité limite (ou émotionnellement labile) reflétés par ses attitudes parfois impulsives de même que par des états émotionnels souvent perturbés. Cela dit, les divergences quant au classement des symptômes de Mozart dans le champ du trouble bipolaire ou de celui d'un trouble de la personnalité rejoignent des incertitudes nosologiques qui aujourd'hui encore soulignent les limites des classifications des troubles mentaux.

The ICD-10 (International classification of diseases, 10th revision), in its chapter dealing with mental disorders, has been constructed in a way that allows it to be used in various cultural settings. This classification can also provide a tool for diagnosing people who lived before the conceptualization of modern psychiatric nosology. Mozart (1756-1791) is perhaps one of the most famous composers, due to the genius of his music but also as a result of his controversial "temperament". Beyond the reputation that arises from these sources, the exact personality and psychiatric disorder(s) from which Mozart may have suffered are still not sufficiently understood. The study of Mozart's letters and his biography leads us to consider the psychiatric disorders from which he may have suffered. We detail some elements of his biography in connection with plausible psychopathological episodes, thus drawing new conclusions about the disorders from which he suffered. Mozart was born in Salzburg in 1756 to a musician father and a mother who had already given birth to six other infants, only one of whom was still living at the time, a four-year-old sister. He became a talented composer but was described as unpretentious, kind, cheerful and extraverted. During his adolescence, there is no indication of the presence of any mental disorder. But later, in accordance with previous literature, it seems that he demonstrated depressive episodes, some of which were severe and correspond to the criteria of the international classification ICD-10. In June 1788 for example, Mozart wrote: "... if such black thoughts did not come to me so often, thoughts which I banish by a tremendous effort, things would be even better." This remark constitutes a relatively specific element in favor of a depressive episode, even if no other clues appear in his letters from this period. In 1790, Mozart's words then explicitly indicate that he suffered from a severe depressive episode: he mentioned a depressed mood, a markedly diminished interest in his activities (e.g. in composing), a diminished ability to concentrate, loss of energy and feelings of excessive guilt. Thus, Mozart described five criteria for the diagnosis of a major depressive episode. "If people could see into my heart, I should almost feel ashamed - to me everything is cold - cold as ice." However, others have claimed the occurrence of some depressive episodes (for instance after the death of his mother) that are excluded by this nosological conception. Also, the arguments put forward by other authors supporting the occurrence of manic or hypomanic episodes (thus constituting a bipolar disorder diagnosis) are not supported by sufficient historic proof. He wrote letters which were incoherent in some parts; but hypomanic episodes can be excluded, as letters written the days before and after these above-mentioned ones are clearly and adequately conceived. This excludes the likelihood of a hypomanic state of duration of more than four days, as required by ICD-10 criteria. Thus, there are no diagnostic criteria for a bipolar II disorder (i.e. the presence of depressive and hypomanic episodes). The diagnosis of a cyclothymic disorder is more difficult to exclude: the length of hypomanic periods is not specified in classifications, but the symptoms must cause clinically significant distress or impairment in social functioning. Mozart suffered social and interpersonal difficulties (i.e. lack of security, affective loneliness), which are at least partially related to some of his behaviors and/or mood instability. This could be due to the presence of a personality disorder. Mozart featured personality traits which correspond to the criteria for dependent personality: difficulties acting on his own (for instance with regard to his relationship with his father); need to be nurtured and supported by others (i.e. his wife); feeling uneasy or helpless when alone. Traits of the borderline personality disorder can also be drawn from his correspondence: efforts to avoid real or imagined abandonment; impulsiveness (also described in some of his biographies); affective instability due to a marked reactivity of mood (which may account for some clinical situations having been described as depressive episodes); and a feeling of emptiness. The current conceptualization of psychiatric disorders allows us to conclude that Mozart suffered from depressive episodes in the background of a personality disorder characterized by dependent as well as borderline traits. Nevertheless, this conclusion may be challenged by authors who consider that the mood lability and brief hypomanic-like episodes that Mozart featured represent core characteristics of the so-called "soft bipolar spectrum" rather than a personality disorder feature. Indeed, there is a growing trend to lower the time criterion for hypomania and even to include hyperthymic traits (which are indisputably present in Mozart) as a constitutive element of a bipolar II disorder in the presence of depressive episodes. Thus, the psychiatric history of Mozart exemplifies nosological uncertainties that are still a source of debate in today's psychiatric research.