Peer reviewed: Yes
Method of research: Systematic review
Subject of study: People  

A systematic review published today in the scientific journal Addiction has found that cannabis use leads to acute cognitive impairments that may continue beyond the period of intoxication. This Canadian-led meta-review (review of reviews) merged the findings of 10 meta-analyses representing more than 43,000 participants.  

The study found that cannabis intoxication leads to small to moderate cognitive impairments in areas including

• making decisions,
• suppressing inappropriate responses,
• learning through reading and listening,
• the ability to remember what one reads or hears, and
• the time needed to complete a mental task. 

These and other acute impairments mirror the residual effects documented for cannabis use, suggesting that the damaging effects of cannabis begin while it