Nearly 14% of teens who participated in a survey reported trying to kill themselves, with transgender teens reporting the highest rates of suicide attempts. Among female to male teens, the language the study uses for transgender male teens, more than half (50.8%) said they'd tried to take their lives, according to the study , published Tuesday in the journal Pediatrics.

"Gender identity is one's own understanding of being male, female, neither, or both," Russell B. Toomey, lead author of the study and an associate professor of family studies and human development at the University of Arizona, wrote in an email.

For most people, their sense of being male or female aligns with what's listed on their birth certificate, he said. However, "a smaller proportion of the population identifies as transgender, which includes people whose internal sense of gender identity" is not consistent with their gender at birth.

'Discrimination, victimization, and rejection'

The new study is based on data from the Profiles of Student Life: Attitudes and Behaviors survey produced by Search Institute , a Minneapolis-based nonprofit focused on youth issues. The survey includes self-reported responses from 120,617 people between the ages of 11 and 19, beginning in June 2012 and ending in May 2015.

The sample included 202 teens (0.2%) who identified as male-to-female transgender, 175 (0.1%) who were female-to-male transgender and 344 (0.3%) not exclusively male or female transgender, also called nonbinary. About 0.9% of the surveyed teens (1,052) reported questioning or not being sure of their gender identity. Additionally, 50.6% (60,973) of females identified as female, and 48% (57,871) of males identified as male. (The researchers rounded up the percentages for publication.)

Asking for help The suicide rate in the United States has seen sharp increases in recent years. Studies have shown that the risk of suicide declines sharply when people call the national suicide hotline: 1-800-273-TALK. There is also a crisis text line. For crisis support in Spanish, call 1-888-628-9454. The lines are staffed by a mix of paid professionals and unpaid volunteers trained in crisis and suicide intervention. The confidential environment, the 24-hour accessibility, a caller's ability to hang up at any time and the person-centered care have helped its success, advocates say.



The International Association for Suicide Prevention and Befrienders Worldwide also provide contact information for crisis centers around the world.

Among the survey questions: "Have you ever tried to kill yourself?"

More than 14% (17,007 respondents) said they had, which is in line with other research , Toomey and his colleagues wrote.

In addition to high rates of suicide attempts among female-to-male transgender respondents, 41.8% of adolescents who identified as neither male nor female said they'd attempted suicide; 29.9% of male-to-female transgender respondents, 27.9% of questioning adolescents, 17.6% of females identifying as female and 9.8% of males identifying as male responded the same, the study found.

Toomey believes that "research is critically needed" to understand why suicide attempts are highest among transmasculine (female-to-male youth) and nonbinary youth (neither male nor female).

What is known is that transgender teens are more likely "to experience discrimination, victimization, and rejection, which are all associated with increased risk for suicidal behaviors," he said. "Other research suggests that the lack of connection and belonging, as well as feeling like a burden to society, are key predictors of suicidal behavior."

Family support is a game-changer, Toomey said: When transgender youth feel that support, "they are more likely to thrive and exhibit similar levels of psychological functioning" as their peers.

Impulsivity and inhibition

Heather Huszti , chief psychologist at Children's Hospital of Orange County in California, said the numbers are generally higher in all populations that "have increased stigma attached to them -- or a lack of understanding."

Feeling marginalized, stigmatized and isolated also "leads a lot of kids to that level of hopelessness and helplessness, which is one of the things that can fuel depression and substance use," said Huszti, who was not involved in the new study. She added that "substance use and depression together can also make you more at risk for suicide."

Why are teens so vulnerable?

"That's the million-dollar question, because we're seeing those rates rise," Huszti said.

"They're very impulsive," she said. "For adolescents, in particular, a large percentage -- I think it's like 50% to 60% -- make an attempt within 30 minutes of having the idea. Their brain isn't developed enough."

Substance users "might be a little more inclined to be disinhibited," she said. Lacking the ability to access resources is another key factor. Although adults can simply choose to see a counselor, "as a teen, you might have to say to your parents, 'I need to go and see a therapist.' "

Get CNN Health's weekly newsletter Sign up here to get The Results Are In with Dr. Sanjay Gupta every Tuesday from the CNN Health team.

"It's probably also somewhat hormonal," Huszti said, explaining that a leap in the numbers of females experiencing depression occurs "around the time they hit puberty, and they have a lifetime greater risk of depression than do males."

Carl Tishler, an adjunct associate professor of psychology and psychiatry at The Ohio State University, said the study's finding of a comparatively higher rate of attempted suicide among transgender youth "speaks to confusion."

"These are young people who are not clear who they are on the outside versus who they are on the inside," said Tishler, who was not involved in the research. "We, as professionals and parents and teachers and coaches, have to pay close attention to these young people."