Men with severe depression are more likely to commit suicide if they abuse alcohol and have “cluster B” personality disorder, which relates to impulsive and/or aggressive behavior, new study findings suggest.

“Why some patients with major depressive disorder die by suicide while others with seemingly the same disorder do not, is a question of enormous clinical relevance,” Dr. Gustavo Turecki and colleagues write in the American Journal of Psychiatry.

The researchers compared psychiatric factors among men with major depressive disorder, 104 of whom committed suicide and 74 who are alive. Psychiatric disorders were determined using proxy-based interviews of relatives, friends or significant others. The two groups were similar in terms of age, marital and parental status, education level, race and religion.

Personality disorders characterized by the presence of impulsive or aggressive personality traits - borderline and antisocial - were associated with a 17-fold greater likelihood of committing suicide. With alcohol abuse or dependence for the last 6 months, the risk increased 4-fold.

These observations “support the vision that higher levels of impulsive and aggressive behaviors combined with behavioral disinhibition facilitated by substance use may mediate suicide in major depressive disorder,” the team concludes.

“When we looked at the effects of age, those risk factors were particularly more important among younger cases,” Turecki told Reuters Health.

“So if a clinician has a patient that has major depression and comorbidity with substance-related problems and the presence of cluster B personality trait and is younger, these are patients you want to make sure you pay close attention to,” he added.

“Further studies should be carried out to investigate the external validity of these findings, particularly among women and in other diagnostic categories associated with suicide such as schizophrenia,” Turecki concluded.

SOURCE: American Journal of Psychiatry, November 2005.