Depression, teens and marijuana are a dangerous mix that can lead to dependency, mental illness or suicidal thoughts, according to a White House report being released Friday.

A teen who has been depressed at some point in the past year is more than twice as likely to have used marijuana as teens who have not reported being depressed _ 25 percent compared with 12 percent, said the report by the White House Office of National Drug Control Policy.

"Marijuana is a more consequential substance of abuse than our culture has treated it in the last 20 years," said John Walters, director of the office. "This is not just youthful experimentation that they'll get over as we used to think in the past."

Smoking marijuana can lead to more serious problems, Walters said in an interview.

For example, using marijuana increases the risk of developing mental disorders by 40 percent, the report said. And teens who smoke pot at least once a month over a yearlong period are three times more likely to have suicidal thoughts than nonusers, it said.

The report also cited research that showed that teens who smoke marijuana when feeling depressed were more than twice as likely as their peers to abuse or become addicted to pot _ 8 percent compared with 3 percent.

Experts who have worked with children say there's nothing harmless about marijuana.

"I've seen many, many kids' lives negatively impacted and taken off track because of marijuana," said Elizabeth Stanley-Salazar, director of adolescent services for Phoenix House treatment centers in California. "It's somewhat Russian roulette. There are so many factors, emotional, psychological, biological. You can't predict the experimentation and how it will impact a kid."

The drug control policy office analyzed about a dozen studies looking at marijuana use, including research by the federal Centers for Disease Control and Prevention and the Substance Abuse and Mental Health Services Administration.

Overall, marijuana use among teens has decreased 25 percent since 2001, down to about 2.3 million kids who used pot at least once a month, the drug control office said.

While the drop is encouraging, Walters appealed to parents to recognize signs of possible drug use and depression.

"It's not something you look the other way about when your teen starts appearing careless about their grooming, withdrawing from the family, losing interest in daily activities," Walters said. "Find out what's wrong."

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On the Net:

White House Office of National Drug Control Policy: http://www.whitehousedrugpolicy.gov