Marijuana affects the brain in several ways. It has an active chemical such as tetra hydro cannabinol, cannabidiol, and cannabinol that can affect the mental state, short term-memory, ocular pressure, and reasoning. People criticize marijuana as being a “gateway drug” and think it’s not that serious. Unfortunately, fatal car accidents involving marijuana have more than tripled in the past decade. Still think it’s not that serious? Check out the marijuana chemical components and effects.