Major depression is growing among young people. One of the drivers may be related to increased cellphone use among teens and girls in particular, U.S. researchers say.

Researchers looked at data from national surveys on drug use and health from 2005 to 2014 for tees aged 12 to 17 and young adults aged 18 to 25.

The U.S. National Institute of Mental Health defines major depressive episode as a period of two weeks or longer during which there is either depressed mood or loss of interest or pleasure, and at least four other symptoms that reflect a change in functioning, such as problems with sleep, eating, energy, concentration, and self-image.

The 12-month prevalence of major depressive episodes increased in adolescents from 8.7 per cent in 2005 to 11.3 per cent in 2014, Dr. Ramin Mojtabai of Johns Hopkins University in Baltimore, Md., and his co-authors said in Monday's issue of the journal Pediatrics.

Dr. Sandra Mendlowitz is a psychologist in the Child and Youth Psychiatry Outpatient Program, SickKids Hospital. (CBC)

"For example, cyberbullying may have increased more dramatically among girls than boys," they wrote. "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."

But the causes of the trend remain elusive.

The findings were based on self-reports from adolescents.

Each year, almost 1 in 11 adolescents and young adults in the U.S. have a major depressive episode and the prevalence increased over the study period. The trend occurred among those in the 12 to 20 age range.

The researchers speculated that adolescence girls may have been exposed to a greater degree of depression risk factors compared with their male peers.

A journal commentary published with the study called on pediatricians to recognize and identify risk factors for suicide.

"Depression is a sizeable and growing deadly threat to our U.S. adolescent population," wrote Dr. Anne Glowinski of the child and adolescent psychiatry division at Washington University in St. Louis, Mo.

More girls are generally willing to seek out therapy or reach out for help for depression than boys, said Dr. Sandra Mendlowitz, a psychologist in the child and youth psychiatry outpatient program at Toronto's SickKids Hospital. She was not involved in the research.

Mendlowitz said social media plays a large role because having a social media presence is important in teens' lives.

"You can have a number of likes and dislikes that many teenagers see as destroying their sense of self," Mendlowitz said in an interview with CBC News Network. That's why it's important to be careful about posts and how you'll handle the responses, she said.

In July, the Centre for Addiction and Mental Health (CAMH) said its survey of more than 10,000 Ontario students in Grades 7 to 12 during the 2014-15 school year suggested the number experiencing moderate to serious psychological distress — defined as symptoms of depression and anxiety on a standard screening tool — in the past month jumped to 34 per cent in 2015 from 24 per cent in 2013.

Nationally, the rate of emergency department visits for mental disorders by young Canadians increased by 45 per cent from 2006 to 2014, according to the Canadian Institute for Health Information.

Where to get help

Kids Help Phone – 1-800-668-6868 (Phone), Live Chat (online chat counselling) - visit www.kidshelpphone.ca

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