HALIFAX -- As the federal government ponders how to carry out a promise to legalize marijuana, the arms-length agency that studies addiction is embarking on a four-city tour to spread warnings about the effects of the drug on young people.

The Canadian Centre on Substance Abuse opens the tour in Halifax on Friday with a panel of three experts who contributed to a report released in June that addressed the issue of cannabis use in adolescence.

Dr. Amy Porath-Waller, the centre's director of research and policy, characterizes the timing of the sessions as a bit of "serendipity" given the Liberal government's December throne speech in which it pledged to "legalize, regulate and restrict access to marijuana."

"It's great timing as the discussions are ongoing because we know the focus has been keeping cannabis out of the hands of young people," said Porath-Waller.

She said the aim of the tour is to start a conversation on how to protect those under 25, regardless of which direction the government decides to take with the drug.

Porath-Waller said research indicates the risks are greater for younger people who use marijuana because their brains are still in development.

"We know that it impairs cognitive functioning and there are areas of the brain that are involved in thinking, paying attention, memory and decision making that are impacted by the use of this drug," she said.

And while there are gaps in the research, Porath-Waller said there is evidence of emerging trends such as the risk of addiction.

She said the research has found that one in six, or about 17 per cent of people who start using marijuana in adolescence will develop an addiction. She added that researchers are also fairly confident that there is an increased risk of psychosis for those who are vulnerable.

Porath-Waller said the idea of the panel presentations is to engage those dealing with youth including doctors, teachers, guidance counsellors and parents.

"These events are really meant to lift the evidence off the pages of the report and get it into the hands of those who are working with young people . . . so they can make informed decisions," she said.

Porath-Waller said there will also be an effort to deconstruct myths around the drug such as the belief by some that it cures cancer or improves their performance in school.

"We have found that there are a lot of misconceptions out there amongst youth," she said.

Dr. Philip Tibbo and Dr. Sherry Stewart of Dalhousie University's

Psychiatry Department will take part in the Halifax panel along with Dr. Selene Etches, a child and adolescent psychiatrist at the IWK Health Centre.

The discussion will be moderated by Dr. Franco Vaccarino, the chairman of the scientific council for the Canadian Centre on Substance Abuse.

Future panel discussions are scheduled for Feb 3 in Toronto, Feb. 12 in Vancouver, and Feb. 22 in Ottawa.