Marijuana potency rises

"Today's report makes it more important than ever that we get past outdated, anachronistic views of marijuana," said John Walters, director of the White House Office of National Drug Control Policy. He cited baby boomer parents who might have misguided notions that the drug contains the weaker potency levels of the 1970s.

"Marijuana potency has grown steeply over the past decade, with serious implications in particular for young people," Walters said. He cited the risk of psychological, cognitive and respiratory problems, and the potential for users to become dependent on drugs such as cocaine and heroin.

While the drug's potency may be rising,marijuana users generally adjust to the level of potency and smoke itaccordingly, said Dr. Mitch Earleywine, who teaches psychology at theState University of New York in Albany and serves as an adviser formarijuana advocacy groups. "Stronger cannabis leads to less inhaledsmoke," he said.

The White House office attributed the increasesin marijuana potency to sophisticated growing techniques that drugtraffickers are using at sites in the United States and Canada.

A report from the office last month found that ateenager who has been depressed in the past year was more than twice aslikely to have used marijuana than teenagers who have not reportedbeing depressed — 25% compared with 12%. The study said marijuana useincreased the risk of developing mental disorders by 40%.

"The increases in marijuana potency are ofconcern since they increase the likelihood of acute toxicity, includingmental impairment," said Dr. Nora Volkow, director of the NationalInstitute on Drug Abuse, which funded the University of Mississippistudy.

"Particularly worrisome is the possibility thatthe more potent THC might be more effective at triggering the changesin the brain that can lead to addiction," Volkow said.

But there's no data showing that a higherpotency in marijuana leads to more addiction, Earleywine said, andmarijuana's withdrawal symptoms are mild at best. "Mild irritability,craving for marijuana and decreased appetite — I mean those arelaughable when you talk about withdrawal from a drug. Caffeine isworse."

The project analyzed data on 62,797 cannabissamples, 1,302 hashish samples, and 468 hash oil samples obtainedprimarily from seizures by law enforcement agencies in 48 states since1975.