One of the biggest fears among anti-legalization groups was that teen marijuana use would skyrocket if adult-use cannabis became legal.

Yet, a study recently released in the state of Washington shows that just the opposite has happened. Teen marijuana use has dropped, both among high schoolers and middle schoolers.

Teen Marijuana Use

The study, published in the Journal of the American Medical Association, is a joint effort between the RAND Corporation, the Oregon Public Health Division, the Washington State Liquor and Cannabis Board and New York University.

Researchers told the Seattle Times that they found the numbers encouraging, but also cautioned that further study needs to be done.

What the Study Found

Washington legalized recreational marijuana in 2012. You must be 21 to purchase marijuana in the state. Researchers wanted to study the use of cannabis by teens post-legalization to find out if fears about increased teen use had been realized.

The researchers surveyed a small group of teenagers in 8th, 10th and 12th grades between 2014 and 2016. The results, according to the Times, were as follows:

• Among 8th graders, use dropped from 9.8% to 7.3%
• Among 10th graders, use dropped 19.8% to 17.8%
• Among 12th graders, use remained flat at 26.7%

Mary Segawa, the public health-education liaison at the Washington State Liquor and Cannabis Board, told the Times more study is needed and that researchers aren’t sure what caused the drop. However, she said open dialogue with teenagers may have played a role.

She told the Times, “After legalization there was a lot of concern about what this would do for youth use. One of the things legalization did was start conversations.”

Other Studies

Other studies have also shown that marijuana myths that many have considered true for years have not shown up in actual research and studies.

In Colorado, a study earlier this year found that crime rates have not increased since recreational cannabis became legal in the Rocky Mountain State. As might be expected, the number of marijuana-related arrests dropped 52% between 2012 and 2017. However, the study also found that the number of fatal car accidents which involved a driver with THC in their bloodstream dropped from 13% of all fatalities to 8%.

The Colorado study also found no increase in teen marijuana use. Further, the number of juvenile arrests dropped by 16% between 2012 and 2017. The study found that teenagers try alcohol and e-cigarettes more than marijuana.

In 2016, a Cornell University study also found that marijuana use does not necessarily proceed a drop in IQ, another area of concern about cannabis. The study involved comparing twins, one who used marijuana and one who did not. They noted that lower IQ scores actually predated marijuana use in middle school, writing “It may be interpreted that children who are predisposed to intellectual stagnation in middle school are on a trajectory for future marijuana use.”