Does Cannabis Consumption Negatively Affect Cognition? A Review Of The Scientific Evidence

Open Access

Abstract

Objective: This review summarises the existing evidence on the effects that recreational and medical use of cannabis and cannabinoids have on cognitive performance. Methods: Databases (PubMed, Medline, and Google Scholar) were searched from inception to March 2017 by adopting the following key terms: dronabinol, nabilone, nabiximols, cannabis, marijuana, cognition, neurology, and neuropsychology. A total of 94 documents, including reviews, preclinical and clinical studies, industrial and government agencies reports were included in this review. Results: We found that recreational use of cannabis doubles the risk of a fatal traffic accident by impairing attention and lengthening reaction time. Short-term use lowers performance in working memory, attention, executive functions and visual perception tasks. Chronic recreational use in adolescents also doubles the risk of early school-leaving, cognitive impairment and psychoses in adulthood. Adverse effects of cannabis-based medication – dronabinol, nabiximol and nabilone – and ingestion/inhalation of marijuana allowed for medical use include dizziness, drowsiness and short-term memory impairment.Conclusion: Cannabis consumption is associated with significant impairments in a range of cognitive abilities. Of particular concern, early and chronic exposure to cannabis, especially in the adolescence, seems to be associated with irreversible cognitive impairments.Please click PDF below to download the full paper.