Depression rates among LGBQ teenagers continue to remain high in the US, a new study finds.

Researchers found that the rate of depression among teens who identify as lesbian, gay or bisexual remained almost unchanged - but worryingly high - from 1999 to 2017.

These teens were also about twice as likely to report feeling depressed as those who identify as heterosexual.

The team, from the Warren Alpert Medical School of Brown University, in Providence, Rhode Island, says the findings provide further evidence that more aggressive efforts are needed in schools and health clinics to drive down these rates.

A new study from Brown University in Rhode Island found that gay, lesbian and bisexual teens' rates of depression rose slightly from 51.4% in 1999 to 51.9% in 2017 (file image)

The prevalence of depression among US teenagers has been slowly rising over the last 10 years.

A Pew Research Center poll found that, in 2017, 13 percent of American teens between ages 12 and 17 said they had experienced at least one major depressive episode in the last year, up from eight percent in 2007.

But LGBTQ teens have a risk of depression that is 1.5 to two times higher than their straight peers.

And, according to a 2016 report from the Centers for Disease Control and Prevention, gay, lesbian and bisexual high school students are nearly five times as likely to attempt suicide compared to heterosexual students.

'Despite decades of research on treatment for adolescent depression, sexual minority youths remain a particularly at-risk group,' the authors wrote.

For the study, published in JAMA Pediatrics, the team looked at data from the Massachusetts Youth Risk Behavior Surveillance System between 1999 and 2017.

Teenagers between grades nine and 12 self-identified as heterosexual, gay, lesbian, bisexual, or unsure. They also self-reported whether or not they'd had same-sex partners in their lifetime.

The teens were asked if they ever were 'so sad or hopeless almost every day for [two] weeks or more in a row that you stopped doing some usual activities?'

Researchers found that rates of depression among heterosexual teens fell from 29.3 percent in 1999 to 23.7 percent in 2017.

But among 'sexual minority' teens, rates increased slight from 51.4 percent to 51.9 percent over the same time period.

The team also looked at depression rates among those who reported ever having been in a relationship.

Among heterosexual teens, rates fell from 35.5 percent to 29.5 percent and - among LGBTQ teens - rates increased from 48.7 percent to 53.8 percent.

There have been several efforts and organizations set up to help drive down these rates such as the Association of Gay and Lesbian Psychiatrists and the Trevor Project, a support network for LGBTQ youth in crisis.

'These findings lend urgency to the need for studies evaluating effectiveness of existing treatments for adolescent depression in this population,' the authors wrote.

'Addressing mental health disparities remains a priority in research and clinical practice, and there is much opportunity for progress in addressing this public health concern.'