Suicidal Behaviors in Surviving Monozygotic and Dizygotic Co-Twins: is the Nature of the Co-Twin’s Cause of Death a Factor?

The frequency of suicide-related behaviours was compared in twins from 2 survivor groups: those whose co-twin’s deaths were suicides (47 monozygotic & 31 dizygotic) & those whose co-twin’s deaths were nonsuicides (347 monozygotic & 170 dizygotic). The frequency of suicide attempts among suicide survivors was significantly higher in monozygotic than dizygotic twins, while the frequency of suicide attempts among nonsuicide twin survivors did not differ between monozygotic & dizygotic twins. Twin concordance for suicide attempts more likely reflects a genetic predisposition rather than a behavioural reaction to the loss. (22 refs.)