Evidence suggests that cannabis is a component cause in the development and prognosis of psychosis, in which mechanisms of gene-environment interaction are most likely to explain this association. Potential new methods to directly link genetic liability to the effects of cannabis are discussed.
Cannabis is currently the most commonly used illegal psychoactive substance amongst young people aged between 15 and 24, and it seems that 5% of this age group is addicted to it. Many research teams focused particularly on the cognitive disorders caused by cannabis use. Amongst the cognitive functions considered, memory-related, attention-related, psychomotor and motivation-related functions were proved deteriorated by acute and chronic cannabis use; a very important point, especially among teenagers, as possible alteration at the social and academic level could be the outcome. However studies on long-term and persistent cognitive effects haven’t provided convergent conclusions. Methodological differences could partly affect these observations. Therefore it seems necessary to develop studies with larger samples.