My friend is suffering of schizophrenia stage 2.doctors say it can be due to daily intake of weed for a year. is weed that harmful?

MJ is a drug/illicit: Wheat is also known as cannabis, marijuana, mj, and is considered an illicit drug, in the status of a narcotic, schedule one. And someone who has underlying schizophrenia, it may make the symptoms appear worse, or sooner, since it does affect the brain, and cognition, and memory. A lot depends on how much he was smoking, and for how long. This is what his doctor's worried about.