White House Warns of Pot-Depression Link

May 9, 2008 -- White House officials issued a report Friday citing growing evidence of a connection between marijuana use and depression in teens.

The White House reports that 25% of adolescents who have been depressed at some point in the past year have used marijuana, compared with 12% of non-depressed teens. Researchers have long known that drug and alcohol use tend to go hand-in-hand with mental illnesses. Part of the reason is that people with depression and other illnesses often "self-medicate" to ease their symptoms.

But officials are also pointing to evidence that marijuana could actually make depression symptoms worse in teens. The report points to several studies concluding that teens already showing signs of depression are more likely to have severe depression, psychosis, or suicidal thoughts if they use marijuana.

"Marijuana is not safe and it's not a solution for depression," John P. Walters, director of the White House Office of Drug Control Policy, told reporters.

Drug officials say they've had a hard time convincing parents, many of whom smoked marijuana as a sort of rite of passage in the 1960s and 1970s, that the drug is more potent and more dangerous for young people than it once was.

"Everywhere else we have consensus," Walters said, referring to other illegal drugs. "Marijuana is one where we kind of don't have consensus," he said.

"It's gone from a very mild drug (a few decades ago) to a very serious medication for the same amount of smoking," said Larry Greenhill, MD, who is president-elect of the American Academy of Child and Adolescent Psychiatry.

The brain has built-in receptors, known as cannabinoid receptors, which respond to marijuana's active ingredients. Nora Volkow, MD, who heads the National Institute on Drug Abuse, said researchers have increasing evidence that those same receptors also regulate the brain's stress response.

Heavy marijuana use could make the cannabinoid receptors less responsive over time, making the brain less equipped to handle stress and more vulnerable to depression, Volkow says.

Causal Link?

The White House report also cites studies showing that adolescents who smoke marijuana face up to a 40% chance of developing mental disorders later. The report concludes that "using marijuana can cause depression and other mental illnesses."

Though the link between drug use and depression is strong, a causal link has not yet been established, Volkow said.

"Based on the data, I cannot tell you unequivocally marijuana causes depression," Volkow said.

"I think at this stage, that research is early," Walters said. "In short, marijuana makes a bad situation worse."

Does Report Go too Far?

Michael Fendrich, PhD, professor of social work and director of the Center for Addiction and Behavioral Health Research at the University of Wisconsin-Milwaukee, said the White House report "overreaches" in some of its conclusions.

"It's kind of sensationalist," Fendrich told WebMD. He said some studies have found a small increased risk of psychosis after heavy marijuana use.

But most long-term studies have been "very tentative" about linkages between marijuana and depression, Fendrich said. While the association between marijuana use and worsening depression makes "some theoretical sense", most studies have not been able to single out the drug as an independent risk factor, he said.

"Drug use is part of a whole menu of risks that kids are facing right now. And there are a lot of things kids can do to self-medicate, including drinking, which is probably a lot easier to access," he said in an interview.