Programs aimed at preventing teenage suicides may be ineffective or may even make the problem worse, researchers say.

A study involving 973 ninth- and 10th-graders found suicide-prevention programs in schools appeared often to produce negative reactions, especially among those most prone to suicide - the students who had attempted suicide."The attempters' reactions to the programs were generally more negative than those of the non-attempters," wrote researchers led by David Shaffer of Columbia University College of Physicians and Surgeons in New York.

"Attempters exposed to programs were significantly less likely to recommend that the programs be presented to other students and significantly more likely to indicate that talking about suicide in classroom makes some kids more likely to kill themselevs," they said Tuesday in the Journal of the American Medical Association.

The study involved 524 students who were exposed to a program at school aimed at preventing suicide, including 35 students who said they had made at least one suicide attempt, and 449 students who did not go through such a program, including 28 who had attempted suicide.

Of those who attempted suicide, 74 percent thought other students should participate in the programs, compared with 89 percent of those who had not attempted suicide.