Depression is on the rise among American teens and young adults, with adolescent girls showing the greatest vulnerability, a new national survey reveals.

Back in 2005, the risk of major depressive disorder for teenage boys was pegged at 4.5 percent, and 13 percent for teenage girls. By 2014, however, boys’ risk of depression rose to 6 percent, but for girls it soared to more than 17 percent, the survey found.

“These are episodes during which the adolescent experiences five or more depressive symptoms for a period of two weeks or longer,” explained study author Dr. Ramin Mojtabai. He is a professor in the department of mental health at the Johns Hopkins University Bloomberg School of Public Health in Baltimore.

A closer look shows that teen depression risk only started to edge upwards starting in 2012, with risk weighing more heavily on teen girls throughout the survey period. Mojtabai said the findings “are consistent with recent data on trends in suicide in the U.S.”

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Mojtabai and colleagues reported the results online Nov. 14 in the journal Pediatrics.

The study team pointed out that, among American teens and young adults, roughly one in 11 experience a major depressive disorder every year.

The study examined data collected between 2005 and 2014 by the U.S. National Surveys on Drug Use and Health. More than 172,000 American teens (aged 12 to 17) and nearly 179,000 young adults (18 to 25) were included in the analysis.

The result: overall risk over the course of a single year rose from under 9 percent in 2005 to about 11 percent by 2014 among all teens, and from just under 9 percent to a bit shy of 10 percent among young adults.

But across the entire decade, teenage girls were found to be strikingly more vulnerable to depression than teenage boys, the researchers said.

Mojtabai said the jury remains out as to why, though he and other researchers have theorized that girls may simply be exposed to more depression risk triggers than boys.

For example, “there is some research indicating that cyberbullying may have increased more dramatically among girls than boys,” Mojtabai said. In addition, “as compared with adolescent boys, adolescent girls also now use mobile phones with texting applications more frequently and intensively. And problematic mobile phone use among young people has been linked to depressed mood. These associations, however, remain speculative,” he noted.

Dr. Anne Glowinski said she “was disappointed, but not surprised” by the findings, while agreeing that the report “absolutely does not clarify why this is happening.” Glowinski is director of child and adolescent psychiatry education and training at Washington University School of Medicine in St. Louis.

“There are many stressors which impact our youth and could in fact increase the rates of depression in people who are vulnerable to depression. These stressors are not limited to social media and/or cyberbullying,” she noted.

“Economic factors, prospects about the future, neighborhood violence and many other things could be impacting the mental health of our youth,” according to Glowinski, who wrote an editorial that accompanied the study.

“And yes, one of those things could be social media or even something not on the radar, like an increase in sleep deprivation related to excessive Internet use,” she suggested. “I am not telling you the latter is high on my list of suspects, but just that the list of suspected factors is long. There are really many possibilities that should be investigated as soon as possible.”