I will first explain that this is only an idea I have about it. It is not a blind imaginative idea, it is based on things I have learned about a certain subset of schizophrenia and depression. This article was revised on March, 5 2018.
Marijuana has been shown to reduce folic acid in people who smoke it. This reduction in folic acid is believed to be the reason why babies are damaged when the mother smokes.
When your body is not getting enough folic acid, you will have a methylation problem. This methylation problem leads into mental illnesses. Schizophrenia, bipolar, depression and anxiety can result from impaired folic acid.
Knowing this, we know that if you smoke marijuana then you need to supplement folic acid. Not only are people supposed to be supplementing folic acid daily, they also need many other vitamins. Even if you do not smoke, take a multi-vitamin.
The multi-vitamin could prevent retardation in teenagers who they smoke marijuana, and it could prevent birth defect.