The age at which young people start smoking cannabis is important, according to a new study by Montreal researchers, because it may predict future drug consumption habits. 

The study's conclusion? Boys who smoke before the age of 15 are much more likely to be addicted in adulthood than those who start smoking later on.

A year or two can have an impact, they write in their findings.

The risk of having substance abuse problems in adulthood was reduced by 31 percent when teenagers waited an extra year to start rolling their first joints, the researchers argued.

This new study was recently published in the Canadian Journal of Psychiatry.

It was conducted by Charlie Rioux, a doctoral student in psychology and researcher at the University of Montreal, under the direction of professors Natalie Castellanos Ryan and Jean Séguin.

More specifically, they found that people who start smoking cannabis in early adolescence are at a 68 per cent of experiencing drug abuse by the age of 28, but the risk falls to 44 percent for those who start using it between the ages of 15 and 17.

Previous studies only looked at a pivotal age to start smoking: before or after 18 years. This analysis, therefore, is more precise, Castellanos Ryan said.