People who start smoking marijuana at the beginning of their teens are at a higher risk of having a drug abuse problem by the age of 28, a study has found. Researchers from by Universite de Montreal in Canada suggest that found that children in primary school need to be educated about the risks of starting pot smoking, especially now that the potency is much greater than it was in decades past and that public acceptance is being spurred by legalisation in many places. The study found that those who started smoking pot between the age of 15 and 17 were at 44 percent higher risk of developing a drug abuse problem. However, the risk was higher at 68 percent for those who started at an earlier age. "The odds of developing any drug abuse symptoms by age 28 were reduced by 31 percent for each year of delayed onset of cannabis use in adolescence," researchers said. For the study published in the Canadian Journal of Psychiatry, researchers looked at data for 1,030 boys from some of the city's impoverished neighbourhoods begun in the early 1980s. Every year between ages 13 and 17, the boys were asked if they had consumed cannabis at all in the previous year. At 17, and again at 20 and 28, they were asked not only whether they consumed cannabis, but also other drugs, including hallucinogens, cocaine, amphetamines, barbiturates, tranquilisers, heroin, and inhalants. Then the data were correlated with the age at which they started using cannabis. The results confirmed the researchers' suspicions: the younger they started, the more likely the boys had a drug problem later as young men. This is partly explained by the frequency with which they consumed cannabis and other drugs, but those who started before age 15 were at higher risk regardless of how often they consumed. "The odds of developing any drug abuse symptoms by age 28 were non-significant if cannabis use had its onset at ages 15 to 17, but were significant and almost doubled each year if onset was before age 15," researchers said. Even if those who start smoking cannabis at 17 years were at lower risk, frequent users (20 or more times a year) at age 17 had almost double the chance of abuse by age 28 than occasional users. The researchers also found that the earlier that boys were involved in gangs, drank alcohol, got into fights, stole or vandalised property, the earlier they used cannabis and the higher their odds of having drug abuse issues by 28. Those who started drinking at 17 also were at higher risk of having an alcohol problem at 28. The finding that starting pot smoking between ages 13 and 15 increases the odds of developing a drug problem later on makes it all the more important to prevent or reducing cannabis use as early as possible, researchers said. "It may be important to implement these programmes by the end of elementary school to prevent early onset of cannabis use," said Charlie Rioux, a doctoral student at Universite de Montreal. "Since peer influence and delinquency were identified as early risk factors for earlier cannabis onset and adult drug abuse, targeting these risk factors in prevention programs may be important, especially since prevention strategies working on the motivators of substance use have been shown to be effective," said Rioux.