Background: The inconsistency of the results obtained in biological studies of suicidal behavior may be due to the use of broad categories lacking validity. In previous genetic studies, in which we identified an association between a serotonin-related gene and violent suicide attempts, we suggested that a history of major depressive disorder (MDD) might influence this association. In this study, we aimed to clarify the relationships between the violence of suicide attempts, intent to die, and depression in a large sample of suicide attempters.
Method: We investigated intent to die, according to history of violent suicide attempts and MDD, in 502 consecutively admitted suicide attempters. We characterized patients in terms of lifetime DSM-IV Axis I diagnoses, suicidal intent (Beck Suicide Intent Scale), and history of violent suicide attempts.
Results: Suicidal intent, for both the last suicide attempt before admission and the most lethal suicide attempt, was higher in those with history of MDD (p =.03 and p =.04, respectively) but was not affected by history of violent suicide attempt. In violent suicide attempters, suicidal intent was higher in patients with a history of MDD than in patients with no such history (p =.04 for last suicide attempt and p =.02 for most lethal attempt), whereas MDD had no effect on suicidal intent in nonviolent suicide attempters.
Conclusion: Violent suicide attempters constitute a heterogeneous group in terms of suicidal intent. Our results suggest that biological and genetic studies should take into account the method used to attempt suicide, intent to die, and history of MDD.