A new study published February 13, 2019 in JAMA Psychiatry found that marijuana use during the teenage years was associated with a nearly 40% increase in the risk of depression and a 50% increase in the risk of suicidal thoughts in adulthood.

These findings are especially important because marijuana use is high among teenagers. The latest data on adolescent use from the Monitoring the Future study says 14% of eighth graders, 32% of 10th graders and 43% of 12th graders report using marijuana at some point in their lives.

The new study combines data from 11 studies that included a total of 23,317 adolescents who were followed through young adulthood. The results show that marijuana use before age 18 is associated with a risk of depression 1.4 times higher than those who did not use pot. Individuals who used marijuana as teens were also 3.46 times more likely to attempt suicide compared with those who didn’t.

Researchers note that the study doesn’t prove that marijuana use causes depression, but it does show that there is reason for concern. The human brain is not fully developed until age 22 or 23. Marijuana use in adolescence has already been proven to impair attention, learning, and memory. This study indicates there is also a risk of depression. Parents should be aware of these risks and share them with their teens.