But experts say today’s high-THC cannabis products — vastly different than the joints smoked decades ago — are poisoning some heavy users, including teenagers.
The issue is that people adjust their consumption accordingly, just as with alcohol - drinking one liter of beer, everyone knows, is not the same as drinking one liter of vodka. Concentrated hash products were also widely available in past eras. Imagine a headline like "Concentrated alcohol products cause vomiting in teenagers! It's not your parent's booze!"
Regardless, THC negatively impairs learning, as does alcohol, particular when it comes to memory and retention. People who choose to use such substances recreationally should really moderate their intake and not engage in daily use.
This doesn't apply to people who use cannabis for legitimate medical uses, such as an adjunct to opiates to manage serious chronic pain without crossing the addictive threshold with opiates (i.e. avoiding opiate tolerance, which leads to opiate addiction).