Does Marijuana Change the Brain?

The effects of marijuana on the brain may be more complicated than experts previously thought, and may depend on factors related to the person using the drug, such as their genetics, two new studies suggest. Marijuana use does not lead to smaller brain size in teens, one of the new studies found. But in people who are genetically prone to schizophrenia, marijuana could alter their brain development in potentially negative ways, according to the other new study.