Abstract Marijuana and hashish, from the plant Cannabis sativa L, are the illicit drugs most frequently used worldwide. Cannabis is well known for its recreational effects being popular among adolescents and young adults and is often perceived as harmless. Cannabis, however, impairs working and short-term memory and is associated with decline in academic functioning, impaired driving skills, cognitive impairment, and progression to other illicit substance use. Cannabis use has also been linked to a propensity for developing psychotic events while neuroimaging studies indicated brain volume changes in heavy and chronic users. Cannabis effects are ascribed to its major psychoactive constituent delta-9- tetrahydrocannabinol (Δ9-THC) acting...