Marijuana use may cause cognitive impairment even when not still high 

(NBC News) The negative effects of marijuana use continue even after the user is no longer “high,” according to new research. 

Problems with memory and focus, as well as slower brain processing can last for weeks. 

The study, Evidence on the acute and residual neurocognitive effects of cannabis use in adolescents and adults: a systematic meta-review of meta-analyses, was conducted by researchers from the University of Montreal. They based their findings on an analysis from past research about marijuana and young people. Read more.