The influence of comorbidity on the prevalence of suicidal behaviour.

The existence of mental disorders is almost constant in subjects who try to kill themselves. In addition, a majority of attempters have more than one diagnosis. This is especially true if Axis II or Axis I subthreshold conditions are taken into account. The existence of a disorder largely explains the association between most socioeconomic variables (sex, marriage, education level) and suicidality. Depressive disorders are the major risk factor, a risk probably linked to a current episode just before the attempt. The association to depressive episodes of an anxiety disorder or the existence of impulsive traits (and/or cluster B personality disorder or drug abuse) increases the risk of acting out. Ideation and attempts show parallel onset curves peaking between the ages of 14 and 20 years, with the existence of a previous DSM III R diagnosis as a strong predictor. The number of associated disorders linearly increases the probability of attempting suicide and is the only significant predictor for lethality. A proper treatment of mental disorders could substantially lower suicidality.