Adolescents who viewed medical marijuana advertising were more likely to use or contemplate using marijuana, according to a new study.

The study followed 8,214 California students in 16 middle schools during the years 2010 and 2011. The students were asked over time about their exposure to medical marijuana, advertisements for the products and their intentions on using the product. The study found that those who saw an advertisement were 2 times more likely to try the drug than those who had not.

Researchers found that during the first year of their study, over 22 percent of students saw at least one advertisement for medical marijuana. By the next year, this number jumped to 30 percent. That is a big increase in people seeing the ad, and therefore trying the product.

The researchers saw this study as very important because the age of these students is during prime brain development. The marijuana use can greatly affect the development, causing many side effects.