The Detrimental Effects of Cannabis on Brain. A Concise Review

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 shortterm 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-9tetrahydrocannabinol (Δ 9 -THC) acting on at least two types of cannabinoid receptors. The effects of cannabis on brain are influenced by the age of initiating usage, frequency and potency of the cannabis preparation (Δ 9 -THC) as well as the ratio of Δ 9 -THC to the major non-psychotropic cannabidiol. The latter is thought to antagonize some of the adverse effects of Δ 9 -THC. The aim of this review is to summarize the evidence pertaining to the delirious effects of cannabis and its main psychoactive ingredient Δ 9 -THC on the brain.