Frequent use of cannabis during teenage years lowers educational attainment by 60 percent and triggers other problems in young adults, according to a new study by the University of New South Wales.
The researchers said that these teens are seven times more likely to attempt suicide, 18 times at a greater risk of cannabis dependence and eight times more prone to using other illegal drugs in future.
"Our findings are particularly timely given that several US states and countries in Latin America have made moves to decriminalise or legalise cannabis, raising the possibility that the drug might become more accessible to young people", said Richard Mattick, study author and professor of drug and alcohol studies at the National Drug and Alcohol Research Centre, in a statement.
Cannabis is the most commonly used drug globally. Previous studies showed that in some countries, cannabis addiction starts at a younger age and more adolescents are associated with chronic cannabis smoking.
In England, about 4 percent of 11 to 15-year-olds used cannabis in the past month and nearly 7 percent of US high-school seniors are daily cannabis users. In Australia, around 1 percent of 14 to 19-year-olds are daily users of the drug, while 4 percent of them use weekly.
For the study, Australian and New Zealand researchers used data of 3,765 participants who reported cannabis use in three longitudinal studies. They wanted to determine the relationship between the frequency of cannabis use before the age of 17 years and seven outcomes up to the age of 30 (high school and university completion rate, cannabis dependence, use of other illicit drugs, suicide attempt, depression, and welfare dependence).
The researchers found a clear link between frequency of cannabis use during adolescence and known young adult outcomes. The risks increased with higher dose levels, meaning, daily cannabis users displayed the strongest effects.
"Our results provide strong evidence that the prevention or delay of cannabis use is likely to have broad health and social benefits. Efforts to reform cannabis legislation should be carefully assessed to ensure they reduce adolescent cannabis use and prevent potentially adverse effects on adolescent development," said study's lead author Dr Edmund Silins.
