Les pactes suicidaires sont définis comme un accord mutuel généralement entre deux personnes décidant de mourir ensemble, le plus souvent au même endroit. Ces pactes sont relativement rares, représentant 0,56 à 2,5 % des suicides dans les quelques études occidentales de référence. Ils sont classiquement plus fréquents (4 %) au Japon. L'image romantique communément admise de pactes entre amoureux contrariés dans leurs projets d'union, comptant pour 58 % des cas dans une étude statistique au Japon, ne représente qu'une minorité des cas de figure en Occident. La plupart des pactes intéressent plutôt des couples mariés (70 à 78 %) et beaucoup plus rarement des couples d'amants (6,4 à 20 %). Ces suicides à deux paraissent davantage le fait de couples mariés plus âgés, atteints d'affections physiques invalidantes ou douloureuses, socialement isolés et décrivant fréquemment un sentiment de perte d'espoir. L'âge moyen est relativement constant selon les études, de 51 à 56 ans. L'existence menacée d'une relation fusionnelle et exclusive entre les deux partenaires, dont l'un, dominant, devient l'instigateur du double suicide, est soulignée par plusieurs auteurs. Les pactes suicidaires, soigneusement préparés et souvent létaux, doivent éveiller la vigilance des cliniciens en présence de patients envisageant un tel projet ou ayant déjà tenté de se suicider à deux.

Suicide pacts are a mutual arrangement between more often two people who decide to kill themselves together, usually in the same place. After a presentation of some famous cases (Mayerling tragedy, double suicides of Heinrich Kleist, Stefan Zweig, Max Linder or Paul Lafargue), this article describe the epidemiology, circumstances and motivation, mental health, main differential diagnosis, psychopathology and legal issues in suicide pacts. These pacts are relatively rare, between 0.56 and 2.5% of all suicides in reference occidental studies. They are classically more frequent (4%) in Japan. The common romantic view of pacts between lovers unsuccessful in their marriage project, up to 58% of cases in a study in Japan, characterizes only a minority in Occident (6.4 to 20%). These pacts involve more often married couples (70 to 78%), average age being between 51 and 56 years. Couples of aged husbands, depressive, mutually devoted and socially isolated, suffering from physical debiliting or painful illness, are usually concerned. Parents and children, siblings or sometimes friends can also be implicated in suicide pacts. The threat of dissolution of a close, affectionate and exclusive relationship between both partners, one of them being dominant and becoming the instigator of a double suicide, is emphasized by some authors. Such suicide pacts may also occur between persons unknown to themselves before, sparing their difficulties in life on Internet and searching one or more partners to die together. Couples use preferentially the same non-violent method for death, above all intoxication by carbon monoxide from car exhausts or medicines in recent series in England and Wales (89 to 92%). Different means such as submersion, poisoning by other liquid or solid substances, jumping and suffocation can also be used. Firearms are more commonly in cause in homicide-suicide pacts. Considering psychopathology, major depressive disorder of one or both members of the couple seems the most frequent diagnosis, in a context of anxiety or pain related to illness or handicap, financial difficulties and a possible separation. Suicide pacts have also common characteristics with induced psychosis or “folie à deux”, with an exclusive bonding between these persons, social isolation and shared delusive thoughts of financial ruin or disease. In a forensic point of view, differential diagnoses are especially homicides-suicides without the consent of the victim, double or multiple homicides or accidental consequences of a suicide. Most legislations in many countries punish complicity or assistance to suicide and more over homicide. The fact that these suicide pacts are carefully premeditated and frequently lethal must arouse clinicians' attention to patients wishing or having already tried to die together.