Youths that begin drinking alcohol and smoking marijuana in middle school are likely to have mental health problems and academic issues in high school, according to a study published in the journal Addiction.

The study, conducted by the RAND Corporation, followed 6,509 participants that were all part of the drug use prevention program called CHOICE. The participants were surveyed yearly beginning in 2008 and ending in 2015. The surveys began when the adolescents were in sixth or seventh grade. They were questioned on alcohol and marijuana use, as well as their academic success, physical health and mental health.

Most of the participants believed that alcohol has more negative effects than marijuana. However, the study finds that marijuana greatly affects mental health and academic success of students. Marijuana use overall led to poorer functioning in students. It also differed among races. For examples, nonwhite youth had the poorest academic functioning due to marijuana. Asians and other ethnicities had more physical health effects.

Prevention and education is necessary to keep adolescents healthy both physically and mentally.