ATLANTA, Georgia (CNN) -- One evening in 1990, Eliza Noh hung up the phone with her sister. Disturbed about the conversation, Noh immediately started writing a letter to her sister, a college student who was often depressed. "I told her I supported her, and I encouraged her," Noh says.
But her sister never read the letter. By the time it arrived, she'd killed herself.
Moved by that tragedy, Noh has spent much of her professional life studying depression and suicide among Asian-American women. An assistant professor of Asian-American studies at California State University at Fullerton, Noh has read the sobering statistics from the Department of Health and Human Services: Asian-American women ages 15-24 have the highest suicide rate of women in any race or ethnic group in that age group. Suicide is the second-leading cause of death for Asian-American women in that age range. (Watch more about Asian-Americans' feelings of pressure to hide depression )
Depression starts even younger than age 15. Noh says one study has shown that as young as the fifth grade, Asian-American girls have the highest rate of depression so severe they've contemplated suicide.
As Noh and others have searched for the reasons, a complex answer has emerged.
First and foremost, they say "model minority" pressure -- the pressure some Asian-American families put on children to be high achievers at school and professionally -- helps explain the problem.
"In my study, the model minority pressure is a huge factor," says Noh, who studied 41 Asian-American women who'd attempted or contemplated suicide. "Sometimes it's very overt -- parents say, 'You must choose this major or this type of job' or 'You should not bring home As and Bs, only As," she says. "And girls have to be the perfect mother and daughter and wife as well."
Family pressure often affects girls more than boys, according to Dr. Dung Ngo, a psychologist at Baylor University in Texas. "When I go talk to high school students and ask them if they experience pressure, the majority who raised their hands were the girls," he said.
Asian-American parents, he says, are stricter with girls than with boys. "The cultural expectations are that Asian women don't have that kind of freedom to hang out, to go out with friends, to do the kinds of things most teenagers growing up want to do."
And in Asian cultures, he added, you don't question parents. "The line of communication in Asian culture one way. It's communicated from the parents downward," he says. "If you can't express your anger, it turns to helplessness. It turns inward into depression for girls. For boys it's more likely to turn outwards into rebellious behavior and behavioral problems like drinking and fighting."
But Noh says pressure from within the family doesn't completely explain the shocking suicide statistics for young women like her sister.
She says American culture has adopted the myth that Asians are smarter and harder-working than other minorities.
"It's become a U.S.-based ideology, popular from the 1960s onward, that Asian-Americans are smarter, and should be doing well whether at school or work."
Noh added that simply being a minority can also lead to depression.
"My sister had a really low self-image. She thought of herself as ugly," she says. "We grew up in Houston in the '70s and '80s, and at that time in school there were very few Asian faces. The standard of beauty she wanted to emulate was white women." In college, Noh's sister had plastic surgery to make her eyes and nose appear more European-looking.
Heredity, Noh says, also plays a role. She says in her study, many of the suicidal women had mothers who were also suicidal. She says perhaps it's genetic -- some biochemical marker handed down from mother to daughter -- or perhaps it's the daughter observing the mother's behavior. "It makes sense. You model yourself after the parent of the same gender."
As varied as the causes of depression, Noh says she saw just as many approaches to overcoming it.
While some women in her study did seek help through counseling and prescription drugs, most of her subjects were ambivalent or even negative about counseling. "They felt the counselor couldn't understand their situation. They said it would have helped if the counselor were another Asian-American woman."
These women found help through their religious faith, herbs, acupuncture, or becoming involved in groups that help other Asian women.
"It shows the resourcefulness of these women," she says. "They had really diverse healing strategies."