cannabis

Research shows a link between marijuana use and psychosis. Kirill Vasikev/EyeEm/Getty Images hide caption

The rain didn't stop customers from lining up outside Cultivate in Leicester, Mass., on Tuesday — the first day that sales of recreational marijuana became legal in the state. Steven Senne/AP hide caption

Even a week without marijuana use improves young people's ability to learn and remember. BURGER/Canopy/Getty Images hide caption

Baby boomers who use marijuana seem to be using it more often than in previous years, a recent survey finds — 5.7 percent of respondents ages 50 to 64 said they'd tried it in the past month. The drug is also gaining popularity among people in their 70s and 80s. Manonallard/Getty Images hide caption

Canopy Growth Corp., the parent company of Corona beer and other alcoholic drinks, is expanding its partnership with a Canadian pot producer, betting on the continued growth in the medical and recreational cannabis markets. Richard Drew/AP hide caption

A drug made from a derivative of marijuana has been approved for patients with certain forms of epilepsy. Blaine Harrington III/Getty Images hide caption

The Estonian municipality has approved using the marijuana leaf as the official government symbol. It will appear as the government logo, on flags and crest. Susan Montoya Bryan/AP hide caption

Many cancer patients seek treatment with medical marijuana. Jupiterimages/Getty Images hide caption

Former House Speaker John Boehner voted to prohibit medical marijuana as a U.S. congressman from Ohio in 1999, but he came out in support of some uses of cannabis on Wednesday. Lauren Victoria Burke/AP hide caption

Marijuana plants are grown for medicinal purposes in a clandestine greenhouse in Mexico City in 2015. Mexico legalized medical marijuana in 2017, but recreational pot remains largely illegal. Yuri Cortez/AFP/Getty Images hide caption

Congress marijuana Bill Clark/CQ-Roll Call,Inc. via Getty Images hide caption