Worried your kid can't kick his pot-smoking habit? Wait until he hits 21. According to a new study, people drastically boost their alcohol consumption at that age—big surprise there—and cut their pot use at the same time. University of Illinois researchers analyzed five years of data from the National Survey on Drug Use and Health, along with responses from survey participants aged 18 to 24 who estimated the number of times they'd consumed alcohol or used marijuana over the previous 30 days. Researchers found marijuana use was basically stable among people 20 years and 11 months old. But almost overnight, when people turned 21 and gained easy access to alcohol, the likelihood that they had consumed alcohol within 30 days jumped by 16%, while pot use fell by 10%, reports the Washington Post.
"Nothing should change about people's preference because people don't overnight lose their preference for marijuana," says researcher Ben Crost. "Alcohol appears to be a substitute for marijuana." Though men had higher rates of alcohol and pot use, cases of pot smoking fell 7.5% among men and 15% among women around age 21. Crost suggests officials should reassess the minimum legal drinking age. "If you think marijuana is more harmful [than booze], then you might want to consider loosening the restrictions for alcohol," he writes, per EurekAlert, noting restrictions on booze appear to be pushing young adults to use illegal drugs. "Lowering the minimum legal drinking age would decrease the probability of marijuana consumption in young adults by about 10%." (A study recently discovered what happens when you mix booze and pot.)