Cannabis, also known as marijuana among other names, is a psychoactive drug from the Cannabis plant used for medical or recreational purposes. The main psychoactive part of cannabis is tetrahydrocannabinol, one of the 483 known compounds in the plant, including at least 65 other cannabinoids. Cannabis use is growing in the teenage community and not to mention cannabis is illegal. Weed in the teenage brain can cause illness and make you delusional. Among persons aged 18 or older who reported lifetime marijuana use, almost 53 percent report first using marijuana between ages 12 and 17. About 2 percent report that they first used marijuana before age 12. The risk for any stroke could increase by 15 percent and it could jump 29 percent for an ischemic stroke — the most common kind, said lead investigator Dr. Krupa Patel.