If there's one ironclad rule for parents when it comes to pot, it's this: Do everything you can to postpone that crucial moment when your kid takes his first hit. Research shows that the earlier children start smoking marijuana, the greater the likelihood of addiction down the line. "Over half of adult addicts had used pot by 15," says Hedrick. "That's why parents need to keep your children away from it for as long as possible."
The fact that more kids are starting younger is particularly worrisome when you consider the stuff they're inhaling. Potency has hit an all-time high: The average concentration of THC, marijuana's main psychoactive ingredient, is now more than 10 percent, compared with less than 4 percent in 1983, and experts believe the numbers will likely rise over the next several years. At the University of Mississippi Potency Monitoring Project, where thousands of samples of seized marijuana are tested annually, THC levels have already exceeded 30 percent.
There's also growing evidence of a toll on the adolescent brain. Yale researcher Alecia Schweinsburg, PhD, has done the first scans comparing the brain function of two groups of 16- to 18-year-olds—those who have abstained from pot and heavy users (kids who smoke at least every other day) who stopped for one month. While both groups performed similarly on memory tests, scans show that chronic smokers had to utilize far more areas of the brain to get the same results. Schweinsburg intends to follow up when the subjects reach 20, and the prognosis doesn't look good. Similar studies on alcohol that have already been completed show that by the time they turned 20, heavy drinkers were unable to retrieve as many memories as they could just two years earlier.
Sandra Carcamo, a member of PDFA's parent advisory committee who lives in Davidsonville, Maryland, knows the research well. Tenacious about keeping her children away from pot, Sandra's method has been to get in their faces early and often. When her oldest daughter skipped classes in 10th grade, Sandra personally introduced her to the school police officer so he'd have a better shot at catching her the next time. Sandra warned her daughter that if it happened again, she'd take vacation time and spend a week following her to each and every class. And for good measure, she insisted on meeting the girl's friends whenever she went out with them, making the girls come into the house, interviewing them, and taking down their cell phone numbers. "I met with resistance, but I told my daughter she had to play by the rules or stay home," says Sandra. "So far, we've had no problems."
Jorgensen recommends that parents stop and listen to their tweens' and teens' music and use that as a starting point for discussion. "This hip-hop they love is a lot about ganja and weed and running from the cops," she says, adding that it's a parent's job to counteract those messages. Not long ago I walked into the kitchen and found my 15-year-old doing her AP history homework while humming along to a tune on the radio, "Smoke Two Joints" by Sublime. ("I smoke two joints in the morning/I smoke two joints at night/I smoke two joints in the afternoon/It makes me feel all right.") She's a very good kid, and unlike her three older brothers, she's had no pot or alcohol issues. But I still felt I had to say something. I asked her if she knew that Sublime's front man had died of a heroin overdose. "I know, Dad," she said, rolling her eyes. Discussion over, but point made.