"I mistakenly believed the Drug Enforcement Agency listed marijuana as a schedule 1 substance because of sound scientific proof," Dr. Gupta wrote on his CNN blog
. "Surely, they must have quality reasoning as to why marijuana is in the category of the most dangerous drugs that have "no accepted medicinal use and a high potential for abuse."
"They didn't have the science to support that claim, and I now know that when it comes to marijuana neither of those things are true. It doesn't have a high potential for abuse, and there are very legitimate medical applications."
Dr. Sanjay Gupta and documentary 'Weed'
Dr. Gupta came across these revelations, he said, while working on a documentary about medical marijuana called 'Weed'. For that film he traveled the world and talked to "medical leaders, experts, growers and patients" and from having done so looked further into the drug, in particular its use medically. The film has not yet been released.
He now says medical marijuana is effective and for some it is the only drug that has helped them through trying medical conditions, pointing to
Charlotte Figi, a young girl in Colorado, whom Dr. Gupta met. Figi was having 300 seizures weekly but because "Medical marijuana has calmed her brain" it has limited her seizures "to 2 or 3 per month."
Marijuana not for "developing brains"
There are concerns he has "as a father" about marijuana. "Young, developing brains are likely more susceptible to harm from marijuana than adult brains," he said. "Some recent studies suggest that regular use in teenage years leads to a permanent decrease in IQ. Other research hints at a possible heightened risk
of developing psychosis.
"Much in the same way I wouldn't let my own children drink alcohol, I wouldn't permit marijuana until they are adults. If they are adamant about trying marijuana, I will urge them to wait until they're in their mid-20s when their brains are fully developed."
Dr. Gupta, who has appeared on some three dozen TV shows talking about medical issues, pointed out that cigarettes have an addiction rate of close to 30 percent while heroin "hooks" about 25 percent of users and cocaine about 20 percent. He said marijuana also leads to dependance in some of its adult users but in only about "9 or 10 percent."