After a school-based prevention program, European teenagers were about half as likely to attempt suicide or to feel suicidal, a new study shows.

Danuta Wasserman, a professor of psychiatry at the Karolinska Institute in Sweden, said the program was likely successful because students “felt that the power of mastering their feelings, coping with stress and choosing solutions was in their hands and not decided or forced by adults.”

Suicide is the third leading cause of death between the ages of 10 and 24, according to the U.S. Centers for Disease Control and Prevention (CDC). Suicide attempts are even more common, with some research suggesting that 4 to 8 percent of high school students try to kill themselves each year, the CDC says.

Those most at risk have a history of suicide attempts, mental illness or substance abuse, or a family history of mental illness and access to lethal methods.

In 10 European countries, Wasserman's team randomly assigned 168 high schools - with more than 11,000 students overall - to provide one of three suicide prevention programs, or no program at all.

The three programs took different approaches. One program, called Question, Persuade, and Refer, focused on training teachers and administrators to recognize kids at risk. A second, the Youth Aware of Mental Health Program, targeted all students with lectures, role-playing exercises and education about mental health and suicide risk. A third program used mental health professionals to screen at-risk pupils who were referred to them.

The researchers compared the number of suicide attempts by students as well as reports of suicidal thoughts after three months of having the programs in place, and again after a year.

At three months, none of the programs showed a significant effect. After a year, however, schools with the Youth Aware of Mental Health program had half as many suicide attempts and reports of suicidal ideation as the comparison schools with no intervention. The other two programs showed much smaller differences from the no-intervention schools.

In schools with the Youth Aware of Mental Health program, 14 students attempted suicide over the course of the year, and 15 students reported having suicidal thoughts. In the no-intervention schools, there were 34 suicide attempts and 31 reports of suicidal thoughts.

In schools with the faculty-focused program, there were 22 suicide attempts and 29 reports of suicidal thinking among students. In the program that used screening by professionals, there were 20 suicide attempts and 22 reports of suicidal thoughts.

Dr. David Brent, a child and adolescent psychiatrist at Western Psychiatric Institute and Clinic in Pittsburgh wrote an editorial on the new study in The Lancet. He told Reuters Health that education about suicide, and early detection and treatment, are two important aspects of effective prevention programs, and the Youth Aware of Mental Health program meets both standards.

Wasserman said the universal prevention model used in that program is effective because it offers treatment before students show outward signs of risk, and it does not stigmatize anyone.

Prediction is very difficult because so many suicide attempts are impulsive, Brent said in an email.

He said one weakness of the study is its exclusion of students who had recently attempted suicide, so it is unclear how well the programs would have worked for students at the highest risk.

Despite these reservations, Brent said he has faith in such programs and that “suicidal behavior is preventable in adolescents through a school-based intervention protocol.”

U.S. schools offer several programs that focus on suicide prevention, he said, and the University of South Florida publishes a booklet full of resources on effective school-based suicide prevention called The Guide.

Wasserman urges parents to advocate for programs like Youth Aware of Mental Health and to convince school authorities that “the health of young people is important.”