Cannabis is currently the most used illicit substance in the world with a global widespread distribution. Although its acute neurocognitive effects on human behaviour have been reported, there is a lack of robust analysis investigating the link, if any, between chronic cannabis use and neurocognitive function. A systematic review of the literature was conducted in order to identify relevant studies published from 2010 to 2019. A meta-analysis was performed on 13 selected studies testing performance of chronic cannabis users compared with non-users in six different neurocognitive domains. There was a low cross-sectional association between neurocognitive impairments and chronic cannabis use in cognitive impulsivity, cognitive flexibility, attention, short-term memory and long-term memory. No association was found between chronic cannabis use and motor impulsivity. By analysing a specific target population with strict inclusion criteria, these findings provide inconclusive evidence that there are cognitive impairments associated with chronic cannabis use. Future research is needed to determine if the findings of this meta-analysis are biased by the methodological limitations encountered.
Keywords: Attention; Cannabis; Chronic Cannabis use; Cognitive flexibility; Impulsivity; Intelligence; Memory; Meta-analysis; Neuropsychology.
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