Because there is a nationwide move to legalize (or at least decriminalize) pot, there are a lot more studies on it now. Older studies are not always relevant because there is so much more THC in today’s pot. The National Institute on Drug Abuse (NIDA) just issued a press release about findings reported in a New England Journal of Medicine article.
Among the not surprising findings: it’s addictive, it impairs driving, and like alcohol and nicotine it’s a gate- way drug. More surprising: using marijuana as a teenager is more damaging than using it as an adult, probably because the brain is not fully formed until one’s early twenties. The damage to memory and cognition are more pronounced when used by teens. Using it in your early teens permanently decreases one’s adult IQ, even if you don’t smoke as an adult. Another surprising finding: All users have impaired thought and memory while high, but regardless of age, the deficits actually last for days afterward. An estimated 6.5% of 12th-graders nationwide report daily pot smoking, and 60% do not perceive it as dangerous.