TORONTO -- With Ottawa poised to legalize recreational marijuana next year, researchers are keeping a close eye on use of the drug, which has been steadily trending upward over the last couple of decades.

In Ontario, for instance, a survey released Wednesday by the Centre for Addiction and Mental Health (CAMH) found that past-year cannabis use virtually doubled between 1996 and 2015, rising from about eight per cent to almost 15 per cent of respondents.

Significant increases were found among all age groups, but especially among 18- to 29-year-olds, with the proportion of pot smokers jumping from about 18 per cent in 1996 to 38 per cent in 2015.

"We also see that the cannabis-using population is aging, as well," said senior scientist Robert Mann, who co-authored the CAMH Monitor report on substance use and mental health status among a representative sample of more than 5,000 Ontario adults.

Last year, 23 per cent of those using marijuana were aged 50 and older -- an eight-fold jump since 1977, when just three per cent of users were in that age bracket.

The CAMH Monitor is a collection of survey data that has been published every two years for almost the last four decades, allowing researchers to track long-term trends in the use of alcohol, drugs and tobacco, as well as identifying problematic behaviours related to mental health within the province's population.

One finding of particular concern is the proportion of respondents who reported getting behind the wheel after using cannabis. In the last five years, that figure doubled, rising to three per cent in 2015 from 1.5 per cent in 2010.

"A lot of people have the sense that cannabis does not impair your driving or that they're able to compensate for the effects of cannabis on driving," said Mann. "They think it's not as dangerous as alcohol is, and maybe that they're even safer drivers if they're driving after cannabis use.

"That's not true and I think that's a dangerous perception for people to have," he said, noting that research over the last 20 years suggests that getting high on weed significantly increases the risk of being involved in a motor vehicle collision.

Disabusing young people about their notions related to driving under the influence of cannabis is at the heart of a program called Weed Out the Risk, delivered by Springboard, a non-profit service agency that has been taking its message to high school students in the Greater Toronto Area for the last three years.

The program uses videos, interactive games and discussion to educate youth on marijuana's effects on the brain and on one's inability to drive safely due to impaired co-ordination and reflexes, reduced peripheral vision and short-term memory deficits.

Don Cooley, a programs manager at Springboard, said he often sees evidence of young people's lack of knowledge about the drug on social media sites, among them that "the person who smokes pot is the designated driver at a party" and "the one drinking alcohol will smoke pot to sober up to drive home."

"Because of the federal government announcing that they're going to legalize recreational marijuana, we see this as really a pending road safety issue for the future," he said.

Among other emerging issues highlighted in the 2015 CAMH report is the growing use of electronic devices.

"If you look around over the past decade or so, you see there's been a real transformation," said Mann. "We know that we're all more engaged with them -- the smartphones, the computers, the notebooks (and other) devices.

"So the research community is wondering what kind of an impact this has."

The survey showed that on average, Ontario adults are spending more than 11 hours per week on email and social media, and almost four hours per week playing screen-based games over and above time spent on the devices at work or in school.

Based on a series of questions -- including "Have you missed school, work or important social activities because of your use of devices?" -- the survey suggests seven per cent of Ontario adults have a "problematic" involvement with electronic media.

"So, that's over 700,000 people," said Mann, noting that an earlier CAMH survey of Grade 7-12 students found 86 per cent visit social media sites daily and about 16 per cent are online five or more hours per day.

The ubiquitous use of devices like smartphones raises another disturbing issue identified in the 2015 survey -- 37 per cent of respondents reported they had texted while driving at least once during the past year, while 11 per cent admitted texting behind the wheel 30 or more times over the previous year.

"So a very high proportion of drivers report texting and driving," he said. "It ties in with the observation that people are really engaged with their devices, and they're using them perhaps all the time, they're using them while they're driving, which we know is a very hazardous behaviour."

A number of studies have calculated those who text while operating a motor vehicle have a 20-times increased risk of being involved in a collision, Mann said.