Nous rapportons le cas d'un patient présentant un trouble bipolaire de type I diagnostiqué après un premier épisode maniaque survenu tardivement à l'âge de 68 ans. Jusqu'à cet épisode récent, le diagnostic de dépression unipolaire avait été retenu devant l'existence de dépressions récurrentes observées sur une période de 29 ans. L'histoire de ce patient est marquée par un épisode mélancolique consécutif à une mauvaise observance thérapeutique. Au cours de cet épisode est survenu un événement dramatique, celui d'un homicide suivi d'une tentative de suicide. Après échec des traitements antidépresseurs, une lithothérapie est entreprise et poursuivie durant 15 ans avec une bonne efficacité jusqu'à un nouvel arrêt du traitement conduisant à la rechute maniaque. À la lumière de ce cas, les données de la littérature concernant l'épidémiologie et la psychopathologie du suicide altruiste sont rappelées. Les risques évolutifs du trouble bipolaire, la place et l'intérêt du lithium sont discutés.

This case reports on a first manic episode occurring to a 68 year old patient. Until now this male patient had been diagnosed with a recurrent depressive disorder. This depressive illness started 29 years ago and was punctuated by several depressive episodes. During one of these episodes associated to psychotic features, following the lithium discontinuation, the patient committed a homicide-suicide. He was found not to be responsible for his crime and treatment was subsequently restarted. For the next fifteen years the patient was stabilized using the association of antidepressant plus lithium, then lithium alone. Until the current manic episode subsequent to a further lithium discontinuation, the patient thanks to the mood stabilizer, could enjoy a good quality of life with a very satisfying social and professional adjustment. Following the case report, an analysis of published data on epidemiological parameters and risk factors associated was conducted. Findings show that perpetrators of murder suicides are mainly males (> 85 %) suffering from depression (40 % to 75 %). Cases of homicide-suicide more frequently involve individuals committing a violent suicide shortly after (minutes or hours) committing one or more homicides. These cases often occur within a disturbed family context with drugs or alcohol abuse, social or cultural stresses such as poor social level or unemployment being other risk factors. Firearms are the most frequently used in suicides. Reported annual incidence is similar every year, ranging from 0.2 to 0.3 per 100 000 in the United States and other countries. Due to suicide but also to other disorders, mortality and morbidity rates are higher with patients suffering from mood disorders. A long term treatment with lithium results in a decrease of morbidity rate and suicidal risk in the general population.