LOS ANGELES (CBSLA) — About one in five California students have thought about committing suicide, according to an analysis of a statewide student health survey.

A survey distributed to 70 percent of California’s public school ninth and eleventh graders showed that in the last four years, about 18 percent – or one in five – of those students had suicidal thoughts, an analysis from the Southern California News Group found.

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While some schools had about just four percent of students thinking suicidal thoughts, in some schools that number went up to a shocking 70 percent, according to Avi Astor, a professor of social welfare at UCLA who last year co-authored a study on youth suicide in the Journal of Pediatrics.

Most of the schools where there were lower numbers of students with suicidal thoughts were in smaller school district that promote prevention training and have mental health resources. That suggests that addressing suicide in a systemic way – with school social workers, counselors, community resources and peer groups — could help lower those numbers, Astor said.

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“That’s kind of the engine that’s getting a lot of the students to be thinking and behaving in that way,” Astor said. “They have friends that are also dealing with substances, difficult life circumstances, and it kind of feeds one on the other.”

Astor said students working with a peer group helps young people understand it’s not snitching when they hear about a problem, but it is saving lives and supporting friends.

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“I think one of the keys is that everyone in the school, the student, the parents, are not isolated and alone and are not connected to anything, and that’s true in the lunch area and in the yard and after-school programs, and even online,” Astor said.