The Guardian reported Monday on a new study that says there is no evidence that marijuana legalization in the U.S. has led to a spike in use among teenagers. Some opponents of legalization for medicinal and/or recreational use worry about the effect less restrictive laws could have on teenagers and young adults, suggesting that greater permissiveness would lead to an increase in use.

The Guardian reports:

"That assumption was the starting point for the research carried out by Dr Deborah Hasin, professor of epidemiology at Columbia University Medical Center in New York, and her colleagues. However, the findings from 24 years of data from more than one million adolescents in the 48 contiguous states did not substantiate those fears. Their paper in the journal Lancet Psychiatry says that the use of cannabis by adolescents was already higher in the states that have opted for medical legalisation. But the change in the law did not lead to a jump in numbers. Analysing data from a national study called Monitoring the Future, which collects information from 50,000 pupils aged 13 to 18 in the 8th, 10th and 12th grade (years 9, 11 and 13 in Britain) every year, they found there had not been a rise even after taking into account individual, school and state-level factors that can affect marijuana use (such as age, ethnicity, public or private school and proportion of each state’s population that was male or white)."

The fact that marijuana use among teenagers was already higher in states that legalized medical marijuana is still a cause for concern for some researchers.

“Because early adolescent use of marijuana can lead to many long-term harmful outcomes, identifying the factors that actually play a role in adolescent use should be a high research priority,” said Dr Deborah Hasin, professor of epidemiology at Columbia University Medical Center in New York.

Supporters of marijuana legalization, either strictly for medicinal purposes or full legalization, will likely find the conclusion of the study encouraging as efforts to legalize marijuana continue to grow in more states.

Read the full report here.