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 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 (Δ9-THC) as well as the ratio of Δ9-THC to the major non-psychotropic cannabidiol. The latter is thought to antagonize some of the adverse effects of Δ9-THC. The aim of this review is to summarize the evidence pertaining to the delirious effects of cannabis and its main psychoactive ingredient Δ9-THC on the brain.
