WEDNESDAY, Nov. 30 (HealthDay News) -- About 40 percent of young adults who've attempted suicide made their first attempt before high school, which suggests that suicidal thoughts and behavior may begin much younger than previously believed, according to a new study.

As part of an ongoing survey, University of Washington researchers asked almost 900 young adults, ages 18 or 19, about their history of suicide attempts.

Nearly 9 percent (78) of the participants said they had attempted suicide at some point. Of those, 40 percent said they made their first attempt before they started high school.

Rates of attempted suicide jumped at around the sixth grade (about age 12) and peaked around eighth or ninth grade. Of the 39 participants who reported multiple suicide attempts, their first attempt was much earlier (as young as age 9) than those who made a single attempt.

The study also found that suicide attempts during childhood and adolescence were linked to higher depression scores at the times of the attempts.

"This suggests that kids are able to tell us, by their depression scores, that things aren't going well for them," lead author James Mazza, a professor of educational psychology, said in a university news release. "We're likely not giving kids enough credence in assessing their own mental health, and this study shows that we can rely on self-report measures to help identify youth who may be at risk for current mental health concerns, including possible suicidal behavior."

Mazza said the study reveals that young adults "who end up having chronic mental health problems show their struggles early," and the findings suggest "that implementation of mental health programs may need to start in elementary and middle schools, and that youth in these grades are fairly good reporters of their own mental health."

The study appears in the November issue of the Journal of Adolescent Health.

According to background information from the researchers, about one in nine youths attempts suicide by the time they graduate from high school.

More information

The U.S. National Institute of Mental Health has more about suicide.