TORONTO -- There has been a steady increase in the prescribing of antidepressants to children and adolescents in Canada, according to new research.

The study, published in the Journal of Child and Adolescent Psychopharmacology, analyzed data collected from 2012 to 2016 for youths under 18. Over the five-year period, Calgary researchers found that prescribing of antidepressants in that age group rose by 36 per cent, from 120 per 100,000 to 160 per 100,000people.

Antidepressant Fluoxetine was the most commonly recommended drug, according to the study.

Co-author Dr. Scott Patten told CTV News that he was “a little” surprised by the results. Most surprising was a 114 per cent rise in prescribing of an older class of medications tricyclic antidepressants, which carry a risk of cardiovascular problems.

“We’ve also looked at the issue of if prevalence of depression is increasing in this age group and we haven’t found evidence that it is so we didn’t expect to see an increase in prescription of these medications,” says Patten, a professor at the Cumming School of Medicine in Calgary.

For youth aged 13 to 18, depression was most commonly associated with antidepressant prescriptions, while anxiety disorder was mostly linked to prescriptions among the other age groups.

While the study shows an increase in prescribing of antidepressants, Health Canada has never officially approved the medications for anyone under 18. Some doctors will use a method called off-label to prescribe antidepressants to young people.

The researchers used a survey administered to 652 physicians in Canada by a database called the Canadian Disease and Therapeutic Index (CDTI).

Patten says their study raises some important questions they were unable to answer.

“The data source that we used limits our ability to interpret the trend,” he said. “It should provide strong motivation for more detailed studies using perhaps different methods that would be able to better understand why we’re seeing this increase in antidepressant recommendations.”

A possible explanation for why more young people are using antidepressants is that the stigma around mental health illness has decreased over time, which could lead to more people seeking treatment, according to Patten.

There also seems to be better mental health literacy among adolescents. “The trend we saw might reflect that,” he says.

The researchers say a negative possibility is that there aren’t enough mental health services and therapists available in Canada.

“It’s conceivable if there are inadequate resources available for people to receive psychotherapy, they may end up receiving pharmacotherapy instead,” says Patten. “Generally, in this age range, the preferred first option for treatment of depression is psychotherapy.”

Mina Tadrous, a scientist with Women’s College Research Institute in Toronto, says it’s possible that some of the medications are being used for other conditions – such as autism, sleep problems or muscle pain.

“We continue to see a rise in the use of this medication, and we need more research to see if this is a good or bad thing, or as I suspect, a bit of both,” Tadrous told CTV News.

Patten thinks “we have to be careful in assuming that the increase is entirely a negative thing.”

“Historically, there has been an underutilization of mental health services. Psychotherapy is the best option for some people, while medication is the best option for other people,” he said. “We don’t want to stigmatize or vilify these medications. We want them to be used in the manner that is the most consistent with achieving the best possible outcome for people.”

Patten says his team is planning additional research as a follow up.