Suicidal behaviour in mood disorders--who, when, and why?

OBJECTIVE: About one-half to two-thirds of all suicides are by people who suffer from mood disorders; preventing suicides among those who suffer from them is thus central for suicide prevention. Understanding factors underlying suicide risk is necessary for rational preventive decisions.
METHOD: The literature on risk factors for completed and attempted suicide among subjects with depressive and bipolar disorders (BDs) was reviewed.
RESULTS: Lifetime risk of completed suicide among psychiatric patients with mood disorders is likely between 5% and 6%, with BDs, and possibly somewhat higher risk than patients with major depressive disorder. Longitudinal and psychological autopsy studies indicate suicidal acts usually take place during major depressive episodes (MDEs) or mixed illness episodes. Incidence of suicide attempts is about 20- to 40-fold, compared with euthymia, during these episodes, and duration of these high-risk states is therefore an important determinant of overall risk. Substance use and cluster B personality disorders also markedly increase risk of suicidal acts during mood episodes. Other major risk factors include hopelessness and presence of impulsive-aggressive traits. Both childhood adversity and recent adverse life events are likely to increase risk of suicide attempts, and suicidal acts are predicted by poor perceived social support. Understanding suicidal thinking and decision making is necessary for advancing treatment and prevention.
CONCLUSION: Among subjects with mood disorders, suicidal acts usually occur during MDEs or mixed episodes concurrent with comorbid disorders. Nevertheless, illness factors can only in part explain suicidal behaviour. Illness factors, difficulty controlling impulsive and aggressive responses, plus predisposing early exposures and life situations result in a process of suicidal thinking, planning, and acts.